wget/doc/wget.texi

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@setfilename wget.info
@documentencoding UTF-8
@include version.texi
@settitle GNU Wget @value{VERSION} Manual
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@c Title for man page.  The weird way texi2pod.pl is written requires
@c the preceding @set.
@set Wget Wget
@c man title Wget The non-interactive network downloader.

@dircategory Network applications
@direntry
* Wget: (wget).                 Non-interactive network downloader.
@end direntry

@copying
This file documents the GNU Wget utility for downloading network
data.

@c man begin COPYRIGHT
Copyright @copyright{} 1996--2011, 2015, 2018--2023 Free Software
Foundation, Inc.

@iftex
Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
@end iftex

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).
@end ignore
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts.  A copy of the license is included in the section entitled
``GNU Free Documentation License''.
@c man end
@end copying

@titlepage
@title GNU Wget @value{VERSION}
@subtitle The non-interactive download utility
@subtitle Updated for Wget @value{VERSION}, @value{UPDATED}
@author by Hrvoje Nikšić and others

@ignore
@c man begin AUTHOR
Originally written by Hrvoje Nikšić <hniksic@xemacs.org>.
Currently maintained by Darshit Shah <darnir@gnu.org> and
Tim Rühsen <tim.ruehsen@gmx.de>.
@c man end
@c man begin SEEALSO
This is @strong{not} the complete manual for GNU Wget.
For more complete information, including more detailed explanations of
some of the options, and a number of commands available
for use with @file{.wgetrc} files and the @samp{-e} option, see the GNU
Info entry for @file{wget}.

Also see wget2(1), the updated version of GNU Wget with even better
support for recursive downloading and modern protocols like HTTP/2.
@c man end
@end ignore

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top, Overview, (dir), (dir)
@top Wget @value{VERSION}

@insertcopying
@end ifnottex

@menu
* Overview::                    Features of Wget.
* Invoking::                    Wget command-line arguments.
* Recursive Download::          Downloading interlinked pages.
* Following Links::             The available methods of chasing links.
* Time-Stamping::               Mirroring according to time-stamps.
* Startup File::                Wget's initialization file.
* Examples::                    Examples of usage.
* Various::                     The stuff that doesn't fit anywhere else.
* Appendices::                  Some useful references.
* Copying this manual::         You may give out copies of this manual.
* Concept Index::               Topics covered by this manual.
@end menu

@node Overview, Invoking, Top, Top
@chapter Overview
@cindex overview
@cindex features

@c man begin DESCRIPTION
GNU Wget is a free utility for non-interactive download of files from
the Web.  It supports @sc{http}, @sc{https}, and @sc{ftp} protocols, as
well as retrieval through @sc{http} proxies.

@c man end
This chapter is a partial overview of Wget's features.

@itemize @bullet
@item
@c man begin DESCRIPTION
Wget is non-interactive, meaning that it can work in the background,
while the user is not logged on.  This allows you to start a retrieval
and disconnect from the system, letting Wget finish the work.  By
contrast, most of the Web browsers require constant user's presence,
which can be a great hindrance when transferring a lot of data.
@c man end

@item
@ignore
@c man begin DESCRIPTION

@c man end
@end ignore
@c man begin DESCRIPTION
Wget can follow links in @sc{html}, @sc{xhtml}, and @sc{css} pages, to
create local versions of remote web sites, fully recreating the
directory structure of the original site.  This is sometimes referred to
as ``recursive downloading.''  While doing that, Wget respects the Robot
Exclusion Standard (@file{/robots.txt}).  Wget can be instructed to
convert the links in downloaded files to point at the local files, for
offline viewing.
@c man end

@item
File name wildcard matching and recursive mirroring of directories are
available when retrieving via @sc{ftp}.  Wget can read the time-stamp
information given by both @sc{http} and @sc{ftp} servers, and store it
locally.  Thus Wget can see if the remote file has changed since last
retrieval, and automatically retrieve the new version if it has.  This
makes Wget suitable for mirroring of @sc{ftp} sites, as well as home
pages.

@item
@ignore
@c man begin DESCRIPTION

@c man end
@end ignore
@c man begin DESCRIPTION
Wget has been designed for robustness over slow or unstable network
connections; if a download fails due to a network problem, it will
keep retrying until the whole file has been retrieved.  If the server
supports regetting, it will instruct the server to continue the
download from where it left off.
@c man end

@item
Wget supports proxy servers, which can lighten the network load, speed
up retrieval and provide access behind firewalls.  Wget uses the passive
@sc{ftp} downloading by default, active @sc{ftp} being an option.

@item
Wget supports IP version 6, the next generation of IP.  IPv6 is
autodetected at compile-time, and can be disabled at either build or
run time.  Binaries built with IPv6 support work well in both
IPv4-only and dual family environments.

@item
Built-in features offer mechanisms to tune which links you wish to follow
(@pxref{Following Links}).

@item
The progress of individual downloads is traced using a progress gauge.
Interactive downloads are tracked using a ``thermometer''-style gauge,
whereas non-interactive ones are traced with dots, each dot
representing a fixed amount of data received (1KB by default).  Either
gauge can be customized to your preferences.

@item
Most of the features are fully configurable, either through command line
options, or via the initialization file @file{.wgetrc} (@pxref{Startup
File}).  Wget allows you to define @dfn{global} startup files
(@file{/usr/local/etc/wgetrc} by default) for site settings. You can also
specify the location of a startup file with the --config option.
To disable the reading of config files, use --no-config.
If both --config and --no-config are given, --no-config is ignored.
 

@ignore
@c man begin FILES
@table @samp
@item /usr/local/etc/wgetrc
Default location of the @dfn{global} startup file.

@item .wgetrc
User startup file.
@end table
@c man end
@end ignore

@item
Finally, GNU Wget is free software.  This means that everyone may use
it, redistribute it and/or modify it under the terms of the GNU General
Public License, as published by the Free Software Foundation (see the
file @file{COPYING} that came with GNU Wget, for details).
@end itemize

@node Invoking, Recursive Download, Overview, Top
@chapter Invoking
@cindex invoking
@cindex command line
@cindex arguments
@cindex nohup

By default, Wget is very simple to invoke.  The basic syntax is:

@example
@c man begin SYNOPSIS
wget [@var{option}]@dots{} [@var{URL}]@dots{}
@c man end
@end example

Wget will simply download all the @sc{url}s specified on the command
line.  @var{URL} is a @dfn{Uniform Resource Locator}, as defined below.

However, you may wish to change some of the default parameters of
Wget.  You can do it two ways: permanently, adding the appropriate
command to @file{.wgetrc} (@pxref{Startup File}), or specifying it on
the command line.

@menu
* URL Format::                  
* Option Syntax::               
* Basic Startup Options::       
* Logging and Input File Options::  
* Download Options::            
* Directory Options::           
* HTTP Options::                
* HTTPS (SSL/TLS) Options::     
* FTP Options::                 
* Recursive Retrieval Options::  
* Recursive Accept/Reject Options::  
* Exit Status::                 
@end menu

@node URL Format, Option Syntax, Invoking, Invoking
@section URL Format
@cindex URL
@cindex URL syntax

@dfn{URL} is an acronym for Uniform Resource Locator.  A uniform
resource locator is a compact string representation for a resource
available via the Internet.  Wget recognizes the @sc{url} syntax as per
@sc{rfc1738}.  This is the most widely used form (square brackets denote
optional parts):

@example
http://host[:port]/directory/file
ftp://host[:port]/directory/file
@end example

You can also encode your username and password within a @sc{url}:

@example
ftp://user:password@@host/path
http://user:password@@host/path
@end example

Either @var{user} or @var{password}, or both, may be left out.  If you
leave out either the @sc{http} username or password, no authentication
will be sent.  If you leave out the @sc{ftp} username, @samp{anonymous}
will be used.  If you leave out the @sc{ftp} password, your email
address will be supplied as a default password.@footnote{If you have a
@file{.netrc} file in your home directory, password will also be
searched for there.}

@strong{Important Note}: if you specify a password-containing @sc{url}
on the command line, the username and password will be plainly visible
to all users on the system, by way of @code{ps}.  On multi-user systems,
this is a big security risk.  To work around it, use @code{wget -i -}
and feed the @sc{url}s to Wget's standard input, each on a separate
line, terminated by @kbd{C-d}.

You can encode unsafe characters in a @sc{url} as @samp{%xy}, @code{xy}
being the hexadecimal representation of the character's @sc{ascii}
value.  Some common unsafe characters include @samp{%} (quoted as
@samp{%25}), @samp{:} (quoted as @samp{%3A}), and @samp{@@} (quoted as
@samp{%40}).  Refer to @sc{rfc1738} for a comprehensive list of unsafe
characters.

Wget also supports the @code{type} feature for @sc{ftp} @sc{url}s.  By
default, @sc{ftp} documents are retrieved in the binary mode (type
@samp{i}), which means that they are downloaded unchanged.  Another
useful mode is the @samp{a} (@dfn{ASCII}) mode, which converts the line
delimiters between the different operating systems, and is thus useful
for text files.  Here is an example:

@example
ftp://host/directory/file;type=a
@end example

Two alternative variants of @sc{url} specification are also supported,
because of historical (hysterical?) reasons and their widespreaded use.

@sc{ftp}-only syntax (supported by @code{NcFTP}):
@example
host:/dir/file
@end example

@sc{http}-only syntax (introduced by @code{Netscape}):
@example
host[:port]/dir/file
@end example

These two alternative forms are deprecated, and may cease being
supported in the future.

If you do not understand the difference between these notations, or do
not know which one to use, just use the plain ordinary format you use
with your favorite browser, like @code{Lynx} or @code{Netscape}.

@c man begin OPTIONS

@node Option Syntax, Basic Startup Options, URL Format, Invoking
@section Option Syntax
@cindex option syntax
@cindex syntax of options

Since Wget uses GNU getopt to process command-line arguments, every
option has a long form along with the short one.  Long options are
more convenient to remember, but take time to type.  You may freely
mix different option styles, or specify options after the command-line
arguments.  Thus you may write:

@example
wget -r --tries=10 http://fly.srk.fer.hr/ -o log
@end example

The space between the option accepting an argument and the argument may
be omitted.  Instead of @samp{-o log} you can write @samp{-olog}.

You may put several options that do not require arguments together,
like:

@example
wget -drc @var{URL}
@end example

This is completely equivalent to:

@example
wget -d -r -c @var{URL}
@end example

Since the options can be specified after the arguments, you may
terminate them with @samp{--}.  So the following will try to download
@sc{url} @samp{-x}, reporting failure to @file{log}:

@example
wget -o log -- -x
@end example

The options that accept comma-separated lists all respect the convention
that specifying an empty list clears its value.  This can be useful to
clear the @file{.wgetrc} settings.  For instance, if your @file{.wgetrc}
sets @code{exclude_directories} to @file{/cgi-bin}, the following
example will first reset it, and then set it to exclude @file{/~nobody}
and @file{/~somebody}.  You can also clear the lists in @file{.wgetrc}
(@pxref{Wgetrc Syntax}).

@example
wget -X "" -X /~nobody,/~somebody
@end example

Most options that do not accept arguments are @dfn{boolean} options,
so named because their state can be captured with a yes-or-no
(``boolean'') variable.  For example, @samp{--follow-ftp} tells Wget
to follow FTP links from HTML files and, on the other hand,
@samp{--no-glob} tells it not to perform file globbing on FTP URLs.  A
boolean option is either @dfn{affirmative} or @dfn{negative}
(beginning with @samp{--no}).  All such options share several
properties.

Unless stated otherwise, it is assumed that the default behavior is
the opposite of what the option accomplishes.  For example, the
documented existence of @samp{--follow-ftp} assumes that the default
is to @emph{not} follow FTP links from HTML pages.

Affirmative options can be negated by prepending the @samp{--no-} to
the option name; negative options can be negated by omitting the
@samp{--no-} prefix.  This might seem superfluous---if the default for
an affirmative option is to not do something, then why provide a way
to explicitly turn it off?  But the startup file may in fact change
the default.  For instance, using @code{follow_ftp = on} in
@file{.wgetrc} makes Wget @emph{follow} FTP links by default, and
using @samp{--no-follow-ftp} is the only way to restore the factory
default from the command line.

@node Basic Startup Options, Logging and Input File Options, Option Syntax, Invoking
@section Basic Startup Options

@table @samp
@item -V
@itemx --version
Display the version of Wget.

@item -h
@itemx --help
Print a help message describing all of Wget's command-line options.

@item -b
@itemx --background
Go to background immediately after startup.  If no output file is
specified via the @samp{-o}, output is redirected to @file{wget-log}.

@cindex execute wgetrc command
@item -e @var{command}
@itemx --execute @var{command}
Execute @var{command} as if it were a part of @file{.wgetrc}
(@pxref{Startup File}).  A command thus invoked will be executed
@emph{after} the commands in @file{.wgetrc}, thus taking precedence over
them.  If you need to specify more than one wgetrc command, use multiple
instances of @samp{-e}.

@end table

@node Logging and Input File Options, Download Options, Basic Startup Options, Invoking
@section Logging and Input File Options

@table @samp
@cindex output file
@cindex log file
@item -o @var{logfile}
@itemx --output-file=@var{logfile}
Log all messages to @var{logfile}.  The messages are normally reported
to standard error.

@cindex append to log
@item -a @var{logfile}
@itemx --append-output=@var{logfile}
Append to @var{logfile}.  This is the same as @samp{-o}, only it appends
to @var{logfile} instead of overwriting the old log file.  If
@var{logfile} does not exist, a new file is created.

@cindex debug
@item -d
@itemx --debug
Turn on debug output, meaning various information important to the
developers of Wget if it does not work properly.  Your system
administrator may have chosen to compile Wget without debug support, in
which case @samp{-d} will not work.  Please note that compiling with
debug support is always safe---Wget compiled with the debug support will
@emph{not} print any debug info unless requested with @samp{-d}.
@xref{Reporting Bugs}, for more information on how to use @samp{-d} for
sending bug reports.

@cindex quiet
@item -q
@itemx --quiet
Turn off Wget's output.

@cindex verbose
@item -v
@itemx --verbose
Turn on verbose output, with all the available data.  The default output
is verbose.

@item -nv
@itemx --no-verbose
Turn off verbose without being completely quiet (use @samp{-q} for
that), which means that error messages and basic information still get
printed.

@item --report-speed=@var{type}
Output bandwidth as @var{type}.  The only accepted value is @samp{bits}.

@cindex input-file
@item -i @var{file}
@itemx --input-file=@var{file}
Read @sc{url}s from a local or external @var{file}.  If @samp{-} is
specified as @var{file}, @sc{url}s are read from the standard input.  
(Use @samp{./-} to read from a file literally named @samp{-}.)

If this function is used, no @sc{url}s need be present on the command
line.  If there are @sc{url}s both on the command line and in an input
file, those on the command lines will be the first ones to be
retrieved.  If @samp{--force-html} is not specified, then @var{file}
should consist of a series of URLs, one per line.

However, if you specify @samp{--force-html}, the document will be
regarded as @samp{html}.  In that case you may have problems with
relative links, which you can solve either by adding @code{<base
href="@var{url}">} to the documents or by specifying
@samp{--base=@var{url}} on the command line.

If the @var{file} is an external one, the document will be automatically
treated as @samp{html} if the Content-Type matches @samp{text/html}.
Furthermore, the @var{file}'s location will be implicitly used as base
href if none was specified.

@cindex input-metalink
@item --input-metalink=@var{file}
Downloads files covered in local Metalink @var{file}. Metalink version 3
and 4 are supported.

@cindex keep-badhash
@item --keep-badhash
Keeps downloaded Metalink's files with a bad hash. It appends .badhash
to the name of Metalink's files which have a checksum mismatch, except
without overwriting existing files.

@cindex metalink-over-http
@item --metalink-over-http
Issues HTTP HEAD request instead of GET and extracts Metalink metadata
from response headers. Then it switches to Metalink download.
If no valid Metalink metadata is found, it falls back to ordinary HTTP download.
Enables @samp{Content-Type: application/metalink4+xml} files download/processing.

@cindex metalink-index
@item --metalink-index=@var{number}
Set the Metalink @samp{application/metalink4+xml} metaurl ordinal
NUMBER. From 1 to the total number of ``application/metalink4+xml''
available.  Specify 0 or @samp{inf} to choose the first good one.
Metaurls, such as those from a @samp{--metalink-over-http}, may have
been sorted by priority key's value; keep this in mind to choose the
right NUMBER.

@cindex preferred-location
@item --preferred-location
Set preferred location for Metalink resources. This has effect if multiple
resources with same priority are available.

@cindex xattr
@item --xattr
Enable use of file system's extended attributes to save the
original URL and the Referer HTTP header value if used.

Be aware that the URL might contain private information like
access tokens or credentials.


@cindex force html
@item -F
@itemx --force-html
When input is read from a file, force it to be treated as an @sc{html}
file.  This enables you to retrieve relative links from existing
@sc{html} files on your local disk, by adding @code{<base
href="@var{url}">} to @sc{html}, or using the @samp{--base} command-line
option.

@cindex base for relative links in input file
@item -B @var{URL}
@itemx --base=@var{URL}
Resolves relative links using @var{URL} as the point of reference,
when reading links from an HTML file specified via the
@samp{-i}/@samp{--input-file} option (together with
@samp{--force-html}, or when the input file was fetched remotely from
a server describing it as @sc{html}). This is equivalent to the
presence of a @code{BASE} tag in the @sc{html} input file, with
@var{URL} as the value for the @code{href} attribute.

For instance, if you specify @samp{http://foo/bar/a.html} for
@var{URL}, and Wget reads @samp{../baz/b.html} from the input file, it
would be resolved to @samp{http://foo/baz/b.html}.

@cindex specify config 
@item --config=@var{FILE}
Specify the location of a startup file you wish to use instead of the
default one(s). Use --no-config to disable reading of config files.
If both --config and --no-config are given, --no-config is ignored.


@item --rejected-log=@var{logfile}
Logs all URL rejections to @var{logfile} as comma separated values.  The values
include the reason of rejection, the URL and the parent URL it was found in.

@end table

@node Download Options, Directory Options, Logging and Input File Options, Invoking
@section Download Options

@table @samp
@cindex bind address
@cindex client IP address
@cindex IP address, client
@item --bind-address=@var{ADDRESS}
When making client TCP/IP connections, bind to @var{ADDRESS} on
the local machine.  @var{ADDRESS} may be specified as a hostname or IP
address.  This option can be useful if your machine is bound to multiple
IPs.

@cindex bind DNS address
@cindex client DNS address
@cindex DNS IP address, client, DNS
@item --bind-dns-address=@var{ADDRESS}
[libcares only]
This address overrides the route for DNS requests. If you ever need to
circumvent the standard settings from /etc/resolv.conf, this option together
with @samp{--dns-servers} is your friend.
@var{ADDRESS} must be specified either as IPv4 or IPv6 address.
Wget needs to be built with libcares for this option to be available.

@cindex DNS server
@cindex DNS IP address, client, DNS
@item --dns-servers=@var{ADDRESSES}
[libcares only]
The given address(es) override the standard nameserver
addresses,  e.g. as configured in /etc/resolv.conf.
@var{ADDRESSES} may be specified either as IPv4 or IPv6 addresses,
comma-separated.
Wget needs to be built with libcares for this option to be available.

@cindex retries
@cindex tries
@cindex number of tries
@item -t @var{number}
@itemx --tries=@var{number}
Set number of tries to @var{number}. Specify 0 or @samp{inf} for
infinite retrying.  The default is to retry 20 times, with the exception
of fatal errors like ``connection refused'' or ``not found'' (404),
which are not retried.

@item -O @var{file}
@itemx --output-document=@var{file}
The documents will not be written to the appropriate files, but all
will be concatenated together and written to @var{file}.  If @samp{-}
is used as @var{file}, documents will be printed to standard output,
disabling link conversion.  (Use @samp{./-} to print to a file
literally named @samp{-}.)

Use of @samp{-O} is @emph{not} intended to mean simply ``use the name
@var{file} instead of the one in the URL;'' rather, it is
analogous to shell redirection:
@samp{wget -O file http://foo} is intended to work like
@samp{wget -O - http://foo > file}; @file{file} will be truncated
immediately, and @emph{all} downloaded content will be written there.

For this reason, @samp{-N} (for timestamp-checking) is not supported
in combination with @samp{-O}: since @var{file} is always newly
created, it will always have a very new timestamp. A warning will be
issued if this combination is used.

Similarly, using @samp{-r} or @samp{-p} with @samp{-O} may not work as
you expect: Wget won't just download the first file to @var{file} and
then download the rest to their normal names: @emph{all} downloaded
content will be placed in @var{file}. This was disabled in version
1.11, but has been reinstated (with a warning) in 1.11.2, as there are
some cases where this behavior can actually have some use.

A combination with @samp{-nc} is only accepted if the given output
file does not exist.

Note that a combination with @samp{-k} is only permitted when
downloading a single document, as in that case it will just convert
all relative URIs to external ones; @samp{-k} makes no sense for
multiple URIs when they're all being downloaded to a single file;
@samp{-k} can be used only when the output is a regular file.

@cindex clobbering, file
@cindex downloading multiple times
@cindex no-clobber
@item -nc
@itemx --no-clobber
If a file is downloaded more than once in the same directory, Wget's
behavior depends on a few options, including @samp{-nc}.  In certain
cases, the local file will be @dfn{clobbered}, or overwritten, upon
repeated download.  In other cases it will be preserved.

When running Wget without @samp{-N}, @samp{-nc}, @samp{-r}, or
@samp{-p}, downloading the same file in the same directory will result
in the original copy of @var{file} being preserved and the second copy
being named @samp{@var{file}.1}.  If that file is downloaded yet
again, the third copy will be named @samp{@var{file}.2}, and so on.
(This is also the behavior with @samp{-nd}, even if @samp{-r} or
@samp{-p} are in effect.)  When @samp{-nc} is specified, this behavior
is suppressed, and Wget will refuse to download newer copies of
@samp{@var{file}}.  Therefore, ``@code{no-clobber}'' is actually a
misnomer in this mode---it's not clobbering that's prevented (as the
numeric suffixes were already preventing clobbering), but rather the
multiple version saving that's prevented.

When running Wget with @samp{-r} or @samp{-p}, but without @samp{-N},
@samp{-nd}, or @samp{-nc}, re-downloading a file will result in the
new copy simply overwriting the old.  Adding @samp{-nc} will prevent
this behavior, instead causing the original version to be preserved
and any newer copies on the server to be ignored.

When running Wget with @samp{-N}, with or without @samp{-r} or
@samp{-p}, the decision as to whether or not to download a newer copy
of a file depends on the local and remote timestamp and size of the
file (@pxref{Time-Stamping}).  @samp{-nc} may not be specified at the
same time as @samp{-N}.

A combination with @samp{-O}/@samp{--output-document} is only accepted
if the given output file does not exist.

Note that when @samp{-nc} is specified, files with the suffixes
@samp{.html} or @samp{.htm} will be loaded from the local disk and
parsed as if they had been retrieved from the Web.

@cindex backing up files
@item --backups=@var{backups}
Before (over)writing a file, back up an existing file by adding a
@samp{.1} suffix (@samp{_1} on VMS) to the file name.  Such backup
files are rotated to @samp{.2}, @samp{.3}, and so on, up to
@var{backups} (and lost beyond that).

@cindex authentication credentials
@item --no-netrc
Do not try to obtain credentials from @file{.netrc} file. By default
@file{.netrc} file is searched for credentials in case none have been
passed on command line and authentication is required.

@cindex continue retrieval
@cindex incomplete downloads
@cindex resume download
@item -c
@itemx --continue
Continue getting a partially-downloaded file.  This is useful when you
want to finish up a download started by a previous instance of Wget, or
by another program.  For instance:

@example
wget -c ftp://sunsite.doc.ic.ac.uk/ls-lR.Z
@end example

If there is a file named @file{ls-lR.Z} in the current directory, Wget
will assume that it is the first portion of the remote file, and will
ask the server to continue the retrieval from an offset equal to the
length of the local file.

Note that you don't need to specify this option if you just want the
current invocation of Wget to retry downloading a file should the
connection be lost midway through.  This is the default behavior.
@samp{-c} only affects resumption of downloads started @emph{prior} to
this invocation of Wget, and whose local files are still sitting around.

Without @samp{-c}, the previous example would just download the remote
file to @file{ls-lR.Z.1}, leaving the truncated @file{ls-lR.Z} file
alone.

If you use @samp{-c} on a non-empty file, and the server does not support
continued downloading, Wget will restart the download from scratch and overwrite
the existing file entirely.

Beginning with Wget 1.7, if you use @samp{-c} on a file which is of
equal size as the one on the server, Wget will refuse to download the
file and print an explanatory message.  The same happens when the file
is smaller on the server than locally (presumably because it was changed
on the server since your last download attempt)---because ``continuing''
is not meaningful, no download occurs.

On the other side of the coin, while using @samp{-c}, any file that's
bigger on the server than locally will be considered an incomplete
download and only @code{(length(remote) - length(local))} bytes will be
downloaded and tacked onto the end of the local file.  This behavior can
be desirable in certain cases---for instance, you can use @samp{wget -c}
to download just the new portion that's been appended to a data
collection or log file.

However, if the file is bigger on the server because it's been
@emph{changed}, as opposed to just @emph{appended} to, you'll end up
with a garbled file.  Wget has no way of verifying that the local file
is really a valid prefix of the remote file.  You need to be especially
careful of this when using @samp{-c} in conjunction with @samp{-r},
since every file will be considered as an "incomplete download" candidate.

Another instance where you'll get a garbled file if you try to use
@samp{-c} is if you have a lame @sc{http} proxy that inserts a
``transfer interrupted'' string into the local file.  In the future a
``rollback'' option may be added to deal with this case.

Note that @samp{-c} only works with @sc{ftp} servers and with @sc{http}
servers that support the @code{Range} header.

@cindex offset
@cindex continue retrieval
@cindex incomplete downloads
@cindex resume download
@cindex start position
@item --start-pos=@var{OFFSET}
Start downloading at zero-based position @var{OFFSET}.  Offset may be expressed
in bytes, kilobytes with the `k' suffix, or megabytes with the `m' suffix, etc.

@samp{--start-pos} has higher precedence over @samp{--continue}.  When
@samp{--start-pos} and @samp{--continue} are both specified, wget will emit a
warning then proceed as if @samp{--continue} was absent.

Server support for continued download is required, otherwise @samp{--start-pos}
cannot help.  See @samp{-c} for details.

@cindex progress indicator
@cindex dot style
@item --progress=@var{type}
Select the type of the progress indicator you wish to use.  Legal
indicators are ``dot'' and ``bar''.

The ``bar'' indicator is used by default.  It draws an @sc{ascii} progress
bar graphics (a.k.a ``thermometer'' display) indicating the status of
retrieval.  If the output is not a TTY, the ``dot'' bar will be used by
default.

Use @samp{--progress=dot} to switch to the ``dot'' display.  It traces
the retrieval by printing dots on the screen, each dot representing a
fixed amount of downloaded data.

The progress @var{type} can also take one or more parameters.  The parameters
vary based on the @var{type} selected.  Parameters to @var{type} are passed by
appending them to the type sperated by a colon (:) like this:
@samp{--progress=@var{type}:@var{parameter1}:@var{parameter2}}.

When using the dotted retrieval, you may set the @dfn{style} by
specifying the type as @samp{dot:@var{style}}.  Different styles assign
different meaning to one dot.  With the @code{default} style each dot
represents 1K, there are ten dots in a cluster and 50 dots in a line.
The @code{binary} style has a more ``computer''-like orientation---8K
dots, 16-dots clusters and 48 dots per line (which makes for 384K
lines).  The @code{mega} style is suitable for downloading large
files---each dot represents 64K retrieved, there are eight dots in a
cluster, and 48 dots on each line (so each line contains 3M).
If @code{mega} is not enough then you can use the @code{giga}
style---each dot represents 1M retrieved, there are eight dots in a
cluster, and 32 dots on each line (so each line contains 32M).

With @samp{--progress=bar}, there are currently two possible parameters,
@var{force} and @var{noscroll}.

When the output is not a TTY, the progress bar always falls back to ``dot'',
even if @samp{--progress=bar} was passed to Wget during invocation. This
behaviour can be overridden and the ``bar'' output forced by using the ``force''
parameter as @samp{--progress=bar:force}.

By default, the @samp{bar} style progress bar scroll the name of the file from
left to right for the file being downloaded if the filename exceeds the maximum
length allotted for its display.  In certain cases, such as with
@samp{--progress=bar:force}, one may not want the scrolling filename in the
progress bar.  By passing the ``noscroll'' parameter, Wget can be forced to
display as much of the filename as possible without scrolling through it.

Note that you can set the default style using the @code{progress}
command in @file{.wgetrc}.  That setting may be overridden from the
command line.  For example, to force the bar output without scrolling,
use @samp{--progress=bar:force:noscroll}.

@item --show-progress
Force wget to display the progress bar in any verbosity.

By default, wget only displays the progress bar in verbose mode.  One may
however, want wget to display the progress bar on screen in conjunction with
any other verbosity modes like @samp{--no-verbose} or @samp{--quiet}.  This
is often a desired a property when invoking wget to download several small/large
files.  In such a case, wget could simply be invoked with this parameter to get
a much cleaner output on the screen.

This option will also force the progress bar to be printed to @file{stderr} when
used alongside the @samp{--output-file} option.

@item -N
@itemx --timestamping
Turn on time-stamping.  @xref{Time-Stamping}, for details.

@item --no-if-modified-since
Do not send If-Modified-Since header in @samp{-N} mode. Send preliminary HEAD
request instead. This has only effect in @samp{-N} mode.

@item --no-use-server-timestamps
Don't set the local file's timestamp by the one on the server.

By default, when a file is downloaded, its timestamps are set to
match those from the remote file. This allows the use of
@samp{--timestamping} on subsequent invocations of wget. However, it
is sometimes useful to base the local file's timestamp on when it was
actually downloaded; for that purpose, the
@samp{--no-use-server-timestamps} option has been provided.

@cindex server response, print
@item -S
@itemx --server-response
Print the headers sent by @sc{http} servers and responses sent by
@sc{ftp} servers.

@cindex Wget as spider
@cindex spider
@item --spider
When invoked with this option, Wget will behave as a Web @dfn{spider},
which means that it will not download the pages, just check that they
are there.  For example, you can use Wget to check your bookmarks:

@example
wget --spider --force-html -i bookmarks.html
@end example

This feature needs much more work for Wget to get close to the
functionality of real web spiders.

@cindex timeout
@item -T seconds
@itemx --timeout=@var{seconds}
Set the network timeout to @var{seconds} seconds.  This is equivalent
to specifying @samp{--dns-timeout}, @samp{--connect-timeout}, and
@samp{--read-timeout}, all at the same time.

When interacting with the network, Wget can check for timeout and
abort the operation if it takes too long.  This prevents anomalies
like hanging reads and infinite connects.  The only timeout enabled by
default is a 900-second read timeout.  Setting a timeout to 0 disables
it altogether.  Unless you know what you are doing, it is best not to
change the default timeout settings.

All timeout-related options accept decimal values, as well as
subsecond values.  For example, @samp{0.1} seconds is a legal (though
unwise) choice of timeout.  Subsecond timeouts are useful for checking
server response times or for testing network latency.

@cindex DNS timeout
@cindex timeout, DNS
@item --dns-timeout=@var{seconds}
Set the DNS lookup timeout to @var{seconds} seconds.  DNS lookups that
don't complete within the specified time will fail.  By default, there
is no timeout on DNS lookups, other than that implemented by system
libraries.

@cindex connect timeout
@cindex timeout, connect
@item --connect-timeout=@var{seconds}
Set the connect timeout to @var{seconds} seconds.  TCP connections that
take longer to establish will be aborted.  By default, there is no
connect timeout, other than that implemented by system libraries.

@cindex read timeout
@cindex timeout, read
@item --read-timeout=@var{seconds}
Set the read (and write) timeout to @var{seconds} seconds.  The
``time'' of this timeout refers to @dfn{idle time}: if, at any point in
the download, no data is received for more than the specified number
of seconds, reading fails and the download is restarted.  This option
does not directly affect the duration of the entire download.

Of course, the remote server may choose to terminate the connection
sooner than this option requires.  The default read timeout is 900
seconds.

@cindex bandwidth, limit
@cindex rate, limit
@cindex limit bandwidth
@item --limit-rate=@var{amount}
Limit the download speed to @var{amount} bytes per second.  Amount may
be expressed in bytes, kilobytes with the @samp{k} suffix, or megabytes
with the @samp{m} suffix.  For example, @samp{--limit-rate=20k} will
limit the retrieval rate to 20KB/s.  This is useful when, for whatever
reason, you don't want Wget to consume the entire available bandwidth.

This option allows the use of decimal numbers, usually in conjunction
with power suffixes; for example, @samp{--limit-rate=2.5k} is a legal
value.

Note that Wget implements the limiting by sleeping the appropriate
amount of time after a network read that took less time than specified
by the rate.  Eventually this strategy causes the TCP transfer to slow
down to approximately the specified rate.  However, it may take some
time for this balance to be achieved, so don't be surprised if limiting
the rate doesn't work well with very small files.

@cindex pause
@cindex wait
@item -w @var{seconds}
@itemx --wait=@var{seconds}
Wait the specified number of seconds between the retrievals.  Use of
this option is recommended, as it lightens the server load by making the
requests less frequent.  Instead of in seconds, the time can be
specified in minutes using the @code{m} suffix, in hours using @code{h}
suffix, or in days using @code{d} suffix.

Specifying a large value for this option is useful if the network or the
destination host is down, so that Wget can wait long enough to
reasonably expect the network error to be fixed before the retry.  The
waiting interval specified by this function is influenced by
@code{--random-wait}, which see.

@cindex retries, waiting between
@cindex waiting between retries
@item --waitretry=@var{seconds}
If you don't want Wget to wait between @emph{every} retrieval, but only
between retries of failed downloads, you can use this option.  Wget will
use @dfn{linear backoff}, waiting 1 second after the first failure on a
given file, then waiting 2 seconds after the second failure on that
file, up to the maximum number of @var{seconds} you specify.

By default, Wget will assume a value of 10 seconds.

@cindex wait, random
@cindex random wait
@item --random-wait
Some web sites may perform log analysis to identify retrieval programs
such as Wget by looking for statistically significant similarities in
the time between requests. This option causes the time between requests
to vary between 0.5 and 1.5 * @var{wait} seconds, where @var{wait} was
specified using the @samp{--wait} option, in order to mask Wget's
presence from such analysis.

A 2001 article in a publication devoted to development on a popular
consumer platform provided code to perform this analysis on the fly.
Its author suggested blocking at the class C address level to ensure
automated retrieval programs were blocked despite changing DHCP-supplied
addresses.

The @samp{--random-wait} option was inspired by this ill-advised
recommendation to block many unrelated users from a web site due to the
actions of one.

@cindex proxy
@item --no-proxy
Don't use proxies, even if the appropriate @code{*_proxy} environment
variable is defined.

@c man end
@xref{Proxies}, for more information about the use of proxies with
Wget.
@c man begin OPTIONS

@cindex quota
@item -Q @var{quota}
@itemx --quota=@var{quota}
Specify download quota for automatic retrievals.  The value can be
specified in bytes (default), kilobytes (with @samp{k} suffix), or
megabytes (with @samp{m} suffix).

Note that quota will never affect downloading a single file.  So if you
specify @samp{wget -Q10k https://example.com/ls-lR.gz}, all of the
@file{ls-lR.gz} will be downloaded.  The same goes even when several
@sc{url}s are specified on the command-line.  The quota is checked only
at the end of each downloaded file, so it will never result in a partially
downloaded file. Thus you may safely type @samp{wget -Q2m -i sites}---download
will be aborted after the file that exhausts the quota is completely
downloaded.

Setting quota to 0 or to @samp{inf} unlimits the download quota.

@cindex DNS cache
@cindex caching of DNS lookups
@item --no-dns-cache
Turn off caching of DNS lookups.  Normally, Wget remembers the IP
addresses it looked up from DNS so it doesn't have to repeatedly
contact the DNS server for the same (typically small) set of hosts it
retrieves from.  This cache exists in memory only; a new Wget run will
contact DNS again.

However, it has been reported that in some situations it is not
desirable to cache host names, even for the duration of a
short-running application like Wget.  With this option Wget issues a
new DNS lookup (more precisely, a new call to @code{gethostbyname} or
@code{getaddrinfo}) each time it makes a new connection.  Please note
that this option will @emph{not} affect caching that might be
performed by the resolving library or by an external caching layer,
such as NSCD.

If you don't understand exactly what this option does, you probably
won't need it.

@cindex file names, restrict
@cindex Windows file names
@item --restrict-file-names=@var{modes}
Change which characters found in remote URLs must be escaped during
generation of local filenames.  Characters that are @dfn{restricted}
by this option are escaped, i.e. replaced with @samp{%HH}, where
@samp{HH} is the hexadecimal number that corresponds to the restricted
character. This option may also be used to force all alphabetical
cases to be either lower- or uppercase.

By default, Wget escapes the characters that are not valid or safe as
part of file names on your operating system, as well as control
characters that are typically unprintable.  This option is useful for
changing these defaults, perhaps because you are downloading to a
non-native partition, or because you want to disable escaping of the
control characters, or you want to further restrict characters to only
those in the @sc{ascii} range of values.

The @var{modes} are a comma-separated set of text values. The
acceptable values are @samp{unix}, @samp{windows}, @samp{nocontrol},
@samp{ascii}, @samp{lowercase}, and @samp{uppercase}. The values
@samp{unix} and @samp{windows} are mutually exclusive (one will
override the other), as are @samp{lowercase} and
@samp{uppercase}. Those last are special cases, as they do not change
the set of characters that would be escaped, but rather force local
file paths to be converted either to lower- or uppercase.

When ``unix'' is specified, Wget escapes the character @samp{/} and
the control characters in the ranges 0--31 and 128--159.  This is the
default on Unix-like operating systems.

When ``windows'' is given, Wget escapes the characters @samp{\},
@samp{|}, @samp{/}, @samp{:}, @samp{?}, @samp{"}, @samp{*}, @samp{<},
@samp{>}, and the control characters in the ranges 0--31 and 128--159.
In addition to this, Wget in Windows mode uses @samp{+} instead of
@samp{:} to separate host and port in local file names, and uses
@samp{@@} instead of @samp{?} to separate the query portion of the file
name from the rest.  Therefore, a URL that would be saved as
@samp{www.xemacs.org:4300/search.pl?input=blah} in Unix mode would be
saved as @samp{www.xemacs.org+4300/search.pl@@input=blah} in Windows
mode.  This mode is the default on Windows.

If you specify @samp{nocontrol}, then the escaping of the control
characters is also switched off. This option may make sense
when you are downloading URLs whose names contain UTF-8 characters, on
a system which can save and display filenames in UTF-8 (some possible
byte values used in UTF-8 byte sequences fall in the range of values
designated by Wget as ``controls'').

The @samp{ascii} mode is used to specify that any bytes whose values
are outside the range of @sc{ascii} characters (that is, greater than
127) shall be escaped. This can be useful when saving filenames
whose encoding does not match the one used locally.

@cindex IPv6
@item -4
@itemx --inet4-only
@itemx -6
@itemx --inet6-only
Force connecting to IPv4 or IPv6 addresses.  With @samp{--inet4-only}
or @samp{-4}, Wget will only connect to IPv4 hosts, ignoring AAAA
records in DNS, and refusing to connect to IPv6 addresses specified in
URLs.  Conversely, with @samp{--inet6-only} or @samp{-6}, Wget will
only connect to IPv6 hosts and ignore A records and IPv4 addresses.

Neither options should be needed normally.  By default, an IPv6-aware
Wget will use the address family specified by the host's DNS record.
If the DNS responds with both IPv4 and IPv6 addresses, Wget will try
them in sequence until it finds one it can connect to.  (Also see
@code{--prefer-family} option described below.)

These options can be used to deliberately force the use of IPv4 or
IPv6 address families on dual family systems, usually to aid debugging
or to deal with broken network configuration.  Only one of
@samp{--inet6-only} and @samp{--inet4-only} may be specified at the
same time.  Neither option is available in Wget compiled without IPv6
support.

@item --prefer-family=none/IPv4/IPv6
When given a choice of several addresses, connect to the addresses
with specified address family first.  The address order returned by
DNS is used without change by default.

This avoids spurious errors and connect attempts when accessing hosts
that resolve to both IPv6 and IPv4 addresses from IPv4 networks.  For
example, @samp{www.kame.net} resolves to
@samp{2001:200:0:8002:203:47ff:fea5:3085} and to
@samp{203.178.141.194}.  When the preferred family is @code{IPv4}, the
IPv4 address is used first; when the preferred family is @code{IPv6},
the IPv6 address is used first; if the specified value is @code{none},
the address order returned by DNS is used without change.

Unlike @samp{-4} and @samp{-6}, this option doesn't inhibit access to
any address family, it only changes the @emph{order} in which the
addresses are accessed.  Also note that the reordering performed by
this option is @dfn{stable}---it doesn't affect order of addresses of
the same family.  That is, the relative order of all IPv4 addresses
and of all IPv6 addresses remains intact in all cases.

@item --retry-connrefused
Consider ``connection refused'' a transient error and try again.
Normally Wget gives up on a URL when it is unable to connect to the
site because failure to connect is taken as a sign that the server is
not running at all and that retries would not help.  This option is
for mirroring unreliable sites whose servers tend to disappear for
short periods of time.

@cindex user
@cindex password
@cindex authentication
@item --user=@var{user}
@itemx --password=@var{password}
Specify the username @var{user} and password @var{password} for both
@sc{ftp} and @sc{http} file retrieval.  These parameters can be overridden
using the @samp{--ftp-user} and @samp{--ftp-password} options for 
@sc{ftp} connections and the @samp{--http-user} and @samp{--http-password} 
options for @sc{http} connections.

@item --ask-password
Prompt for a password for each connection established. Cannot be specified
when @samp{--password} is being used, because they are mutually exclusive.

@item --use-askpass=@var{command}
Prompt for a user and password using the specified command.  If no command is
specified then the command in the environment variable WGET_ASKPASS is used.
If WGET_ASKPASS is not set then the command in the environment variable
SSH_ASKPASS is used.

You can set the default command for use-askpass in the @file{.wgetrc}.  That
setting may be overridden from the command line.

@cindex iri support
@cindex idn support
@item --no-iri

Turn off internationalized URI (IRI) support. Use @samp{--iri} to
turn it on. IRI support is activated by default.

You can set the default state of IRI support using the @code{iri}
command in @file{.wgetrc}. That setting may be overridden from the
command line.

@cindex local encoding
@item --local-encoding=@var{encoding}

Force Wget to use @var{encoding} as the default system encoding. That affects
how Wget converts URLs specified as arguments from locale to @sc{utf-8} for
IRI support.

Wget use the function @code{nl_langinfo()} and then the @code{CHARSET}
environment variable to get the locale. If it fails, @sc{ascii} is used.

You can set the default local encoding using the @code{local_encoding}
command in @file{.wgetrc}. That setting may be overridden from the
command line.

@cindex remote encoding
@item --remote-encoding=@var{encoding}

Force Wget to use @var{encoding} as the default remote server encoding.
That affects how Wget converts URIs found in files from remote encoding
to @sc{utf-8} during a recursive fetch. This options is only useful for
IRI support, for the interpretation of non-@sc{ascii} characters.

For HTTP, remote encoding can be found in HTTP @code{Content-Type}
header and in HTML @code{Content-Type http-equiv} meta tag.

You can set the default encoding using the @code{remoteencoding}
command in @file{.wgetrc}. That setting may be overridden from the
command line.

@cindex unlink
@item --unlink

Force Wget to unlink file instead of clobbering existing file. This
option is useful for downloading to the directory with hardlinks.

@end table

@node Directory Options, HTTP Options, Download Options, Invoking
@section Directory Options

@table @samp       
@item -nd
@itemx --no-directories
Do not create a hierarchy of directories when retrieving recursively.
With this option turned on, all files will get saved to the current
directory, without clobbering (if a name shows up more than once, the
filenames will get extensions @samp{.n}).

@item -x
@itemx --force-directories
The opposite of @samp{-nd}---create a hierarchy of directories, even if
one would not have been created otherwise.  E.g. @samp{wget -x
http://fly.srk.fer.hr/robots.txt} will save the downloaded file to
@file{fly.srk.fer.hr/robots.txt}.

@item -nH
@itemx --no-host-directories
Disable generation of host-prefixed directories.  By default, invoking
Wget with @samp{-r http://fly.srk.fer.hr/} will create a structure of
directories beginning with @file{fly.srk.fer.hr/}.  This option disables
such behavior.

@item --protocol-directories
Use the protocol name as a directory component of local file names.  For
example, with this option, @samp{wget -r http://@var{host}} will save to
@samp{http/@var{host}/...} rather than just to @samp{@var{host}/...}.

@cindex cut directories
@item --cut-dirs=@var{number}
Ignore @var{number} directory components.  This is useful for getting a
fine-grained control over the directory where recursive retrieval will
be saved.

Take, for example, the directory at
@samp{ftp://ftp.xemacs.org/pub/xemacs/}.  If you retrieve it with
@samp{-r}, it will be saved locally under
@file{ftp.xemacs.org/pub/xemacs/}.  While the @samp{-nH} option can
remove the @file{ftp.xemacs.org/} part, you are still stuck with
@file{pub/xemacs}.  This is where @samp{--cut-dirs} comes in handy; it
makes Wget not ``see'' @var{number} remote directory components.  Here
are several examples of how @samp{--cut-dirs} option works.

@example
@group
No options        -> ftp.xemacs.org/pub/xemacs/
-nH               -> pub/xemacs/
-nH --cut-dirs=1  -> xemacs/
-nH --cut-dirs=2  -> .

--cut-dirs=1      -> ftp.xemacs.org/xemacs/
...
@end group
@end example

If you just want to get rid of the directory structure, this option is
similar to a combination of @samp{-nd} and @samp{-P}.  However, unlike
@samp{-nd}, @samp{--cut-dirs} does not lose with subdirectories---for
instance, with @samp{-nH --cut-dirs=1}, a @file{beta/} subdirectory will
be placed to @file{xemacs/beta}, as one would expect.

@cindex directory prefix
@item -P @var{prefix}
@itemx --directory-prefix=@var{prefix}
Set directory prefix to @var{prefix}.  The @dfn{directory prefix} is the
directory where all other files and subdirectories will be saved to,
i.e. the top of the retrieval tree.  The default is @samp{.} (the
current directory).
@end table

@node HTTP Options, HTTPS (SSL/TLS) Options, Directory Options, Invoking
@section HTTP Options

@table @samp
@cindex default page name
@cindex index.html
@item --default-page=@var{name}
Use @var{name} as the default file name when it isn't known (i.e., for
URLs that end in a slash), instead of @file{index.html}.

@cindex .html extension
@cindex .css extension
@item -E
@itemx --adjust-extension
If a file of type @samp{application/xhtml+xml} or @samp{text/html} is 
downloaded and the URL does not end with the regexp 
@samp{\.[Hh][Tt][Mm][Ll]?}, this option will cause the suffix @samp{.html} 
to be appended to the local filename.  This is useful, for instance, when 
you're mirroring a remote site that uses @samp{.asp} pages, but you want 
the mirrored pages to be viewable on your stock Apache server.  Another 
good use for this is when you're downloading CGI-generated materials.  A URL 
like @samp{http://site.com/article.cgi?25} will be saved as
@file{article.cgi?25.html}.

Note that filenames changed in this way will be re-downloaded every time
you re-mirror a site, because Wget can't tell that the local
@file{@var{X}.html} file corresponds to remote URL @samp{@var{X}} (since
it doesn't yet know that the URL produces output of type
@samp{text/html} or @samp{application/xhtml+xml}.

As of version 1.12, Wget will also ensure that any downloaded files of
type @samp{text/css} end in the suffix @samp{.css}, and the option was
renamed from @samp{--html-extension}, to better reflect its new
behavior. The old option name is still acceptable, but should now be
considered deprecated.

As of version 1.19.2, Wget will also ensure that any downloaded files with
a @code{Content-Encoding} of @samp{br}, @samp{compress}, @samp{deflate}
or @samp{gzip} end in the suffix @samp{.br}, @samp{.Z}, @samp{.zlib}
and @samp{.gz} respectively.

At some point in the future, this option may well be expanded to
include suffixes for other types of content, including content types
that are not parsed by Wget.

@cindex http user
@cindex http password
@cindex authentication
@item --http-user=@var{user}
@itemx --http-password=@var{password}
Specify the username @var{user} and password @var{password} on an
@sc{http} server.  According to the type of the challenge, Wget will
encode them using either the @code{basic} (insecure),
the @code{digest}, or the Windows @code{NTLM} authentication scheme.

Another way to specify username and password is in the @sc{url} itself
(@pxref{URL Format}).  Either method reveals your password to anyone who
bothers to run @code{ps}.  To prevent the passwords from being seen,
use the @samp{--use-askpass} or store them in @file{.wgetrc} or @file{.netrc},
and make sure to protect those files from other users with @code{chmod}.  If
the passwords are really important, do not leave them lying in those files
either---edit the files and delete them after Wget has started the download.

@iftex
@xref{Security Considerations}, for more information about security
issues with Wget.
@end iftex

@cindex Keep-Alive, turning off
@cindex Persistent Connections, disabling
@item --no-http-keep-alive
Turn off the ``keep-alive'' feature for HTTP downloads.  Normally, Wget
asks the server to keep the connection open so that, when you download
more than one document from the same server, they get transferred over
the same TCP connection.  This saves time and at the same time reduces
the load on the server.

This option is useful when, for some reason, persistent (keep-alive)
connections don't work for you, for example due to a server bug or due
to the inability of server-side scripts to cope with the connections.

@cindex proxy
@cindex cache
@item --no-cache
Disable server-side cache.  In this case, Wget will send the remote
server appropriate directives (@samp{Cache-Control: no-cache} and
@samp{Pragma: no-cache}) to get the file from the remote service,
rather than returning the cached version. This is especially useful
for retrieving and flushing out-of-date documents on proxy servers.

Caching is allowed by default.

@cindex cookies
@item --no-cookies
Disable the use of cookies.  Cookies are a mechanism for maintaining
server-side state.  The server sends the client a cookie using the
@code{Set-Cookie} header, and the client responds with the same cookie
upon further requests.  Since cookies allow the server owners to keep
track of visitors and for sites to exchange this information, some
consider them a breach of privacy.  The default is to use cookies;
however, @emph{storing} cookies is not on by default.

@cindex loading cookies
@cindex cookies, loading
@item --load-cookies @var{file}
Load cookies from @var{file} before the first HTTP retrieval.
@var{file} is a textual file in the format originally used by Netscape's
@file{cookies.txt} file.

You will typically use this option when mirroring sites that require
that you be logged in to access some or all of their content.  The login
process typically works by the web server issuing an @sc{http} cookie
upon receiving and verifying your credentials.  The cookie is then
resent by the browser when accessing that part of the site, and so
proves your identity.

Mirroring such a site requires Wget to send the same cookies your
browser sends when communicating with the site.  This is achieved by
@samp{--load-cookies}---simply point Wget to the location of the
@file{cookies.txt} file, and it will send the same cookies your browser
would send in the same situation.  Different browsers keep textual
cookie files in different locations:

@table @asis
@item Netscape 4.x.
The cookies are in @file{~/.netscape/cookies.txt}.

@item Mozilla and Netscape 6.x.
Mozilla's cookie file is also named @file{cookies.txt}, located
somewhere under @file{~/.mozilla}, in the directory of your profile.
The full path usually ends up looking somewhat like
@file{~/.mozilla/default/@var{some-weird-string}/cookies.txt}.

@item Internet Explorer.
You can produce a cookie file Wget can use by using the File menu,
Import and Export, Export Cookies.  This has been tested with Internet
Explorer 5; it is not guaranteed to work with earlier versions.

@item Other browsers.
If you are using a different browser to create your cookies,
@samp{--load-cookies} will only work if you can locate or produce a
cookie file in the Netscape format that Wget expects.
@end table

If you cannot use @samp{--load-cookies}, there might still be an
alternative.  If your browser supports a ``cookie manager'', you can use
it to view the cookies used when accessing the site you're mirroring.
Write down the name and value of the cookie, and manually instruct Wget
to send those cookies, bypassing the ``official'' cookie support:

@example
wget --no-cookies --header "Cookie: @var{name}=@var{value}"
@end example

@cindex saving cookies
@cindex cookies, saving
@item --save-cookies @var{file}
Save cookies to @var{file} before exiting.  This will not save cookies
that have expired or that have no expiry time (so-called ``session
cookies''), but also see @samp{--keep-session-cookies}.

@cindex cookies, session
@cindex session cookies
@item --keep-session-cookies
When specified, causes @samp{--save-cookies} to also save session
cookies.  Session cookies are normally not saved because they are
meant to be kept in memory and forgotten when you exit the browser.
Saving them is useful on sites that require you to log in or to visit
the home page before you can access some pages.  With this option,
multiple Wget runs are considered a single browser session as far as
the site is concerned.

Since the cookie file format does not normally carry session cookies,
Wget marks them with an expiry timestamp of 0.  Wget's
@samp{--load-cookies} recognizes those as session cookies, but it might
confuse other browsers.  Also note that cookies so loaded will be
treated as other session cookies, which means that if you want
@samp{--save-cookies} to preserve them again, you must use
@samp{--keep-session-cookies} again.

@cindex Content-Length, ignore
@cindex ignore length
@item --ignore-length
Unfortunately, some @sc{http} servers (@sc{cgi} programs, to be more
precise) send out bogus @code{Content-Length} headers, which makes Wget
go wild, as it thinks not all the document was retrieved.  You can spot
this syndrome if Wget retries getting the same document again and again,
each time claiming that the (otherwise normal) connection has closed on
the very same byte.

With this option, Wget will ignore the @code{Content-Length} header---as
if it never existed.

@cindex header, add
@item --header=@var{header-line}
Send @var{header-line} along with the rest of the headers in each
@sc{http} request.  The supplied header is sent as-is, which means it
must contain name and value separated by colon, and must not contain
newlines.

You may define more than one additional header by specifying
@samp{--header} more than once.

@example
@group
wget --header='Accept-Charset: iso-8859-2' \
     --header='Accept-Language: hr'        \
       http://fly.srk.fer.hr/
@end group
@end example

Specification of an empty string as the header value will clear all
previous user-defined headers.

As of Wget 1.10, this option can be used to override headers otherwise
generated automatically.  This example instructs Wget to connect to
localhost, but to specify @samp{foo.bar} in the @code{Host} header:

@example
wget --header="Host: foo.bar" http://localhost/
@end example

In versions of Wget prior to 1.10 such use of @samp{--header} caused
sending of duplicate headers.

@cindex Content-Encoding, choose
@item --compression=@var{type}
Choose the type of compression to be used.  Legal values are
@samp{auto}, @samp{gzip} and @samp{none}.

If @samp{auto} or @samp{gzip} are specified, Wget asks the server to
compress the file using the gzip compression format. If the server
compresses the file and responds with the @code{Content-Encoding}
header field set appropriately, the file will be decompressed
automatically.

If @samp{none} is specified, wget will not ask the server to compress
the file and will not decompress any server responses. This is the default.

Compression support is currently experimental. In case it is turned on,
please report any bugs to @code{bug-wget@@gnu.org}.

@cindex redirect
@item --max-redirect=@var{number}
Specifies the maximum number of redirections to follow for a resource.
The default is 20, which is usually far more than necessary. However, on
those occasions where you want to allow more (or fewer), this is the
option to use.

@cindex proxy user
@cindex proxy password
@cindex proxy authentication
@item --proxy-user=@var{user}
@itemx --proxy-password=@var{password}
Specify the username @var{user} and password @var{password} for
authentication on a proxy server.  Wget will encode them using the
@code{basic} authentication scheme.

Security considerations similar to those with @samp{--http-password}
pertain here as well.

@cindex http referer
@cindex referer, http
@item --referer=@var{url}
Include `Referer: @var{url}' header in HTTP request.  Useful for
retrieving documents with server-side processing that assume they are
always being retrieved by interactive web browsers and only come out
properly when Referer is set to one of the pages that point to them.

@cindex server response, save
@item --save-headers
Save the headers sent by the @sc{http} server to the file, preceding the
actual contents, with an empty line as the separator.

@cindex user-agent
@item -U @var{agent-string}
@itemx --user-agent=@var{agent-string}
Identify as @var{agent-string} to the @sc{http} server.

The @sc{http} protocol allows the clients to identify themselves using a
@code{User-Agent} header field.  This enables distinguishing the
@sc{www} software, usually for statistical purposes or for tracing of
protocol violations.  Wget normally identifies as
@samp{Wget/@var{version}}, @var{version} being the current version
number of Wget.

However, some sites have been known to impose the policy of tailoring
the output according to the @code{User-Agent}-supplied information.
While this is not such a bad idea in theory, it has been abused by
servers denying information to clients other than (historically)
Netscape or, more frequently, Microsoft Internet Explorer.  This
option allows you to change the @code{User-Agent} line issued by Wget.
Use of this option is discouraged, unless you really know what you are
doing.

Specifying empty user agent with @samp{--user-agent=""} instructs Wget
not to send the @code{User-Agent} header in @sc{http} requests.

@cindex POST
@item --post-data=@var{string}
@itemx --post-file=@var{file}
Use POST as the method for all HTTP requests and send the specified
data in the request body.  @samp{--post-data} sends @var{string} as
data, whereas @samp{--post-file} sends the contents of @var{file}.
Other than that, they work in exactly the same way. In particular,
they @emph{both} expect content of the form @code{key1=value1&key2=value2},
with percent-encoding for special characters; the only difference is
that one expects its content as a command-line parameter and the other
accepts its content from a file. In particular, @samp{--post-file} is
@emph{not} for transmitting files as form attachments: those must
appear as @code{key=value} data (with appropriate percent-coding) just
like everything else. Wget does not currently support
@code{multipart/form-data} for transmitting POST data; only
@code{application/x-www-form-urlencoded}. Only one of
@samp{--post-data} and @samp{--post-file} should be specified.

Please note that wget does not require the content to be of the form
@code{key1=value1&key2=value2}, and neither does it test for it. Wget will
simply transmit whatever data is provided to it. Most servers however expect
the POST data to be in the above format when processing HTML Forms.

When sending a POST request using the @samp{--post-file} option, Wget treats
the file as a binary file and will send every character in the POST request
without stripping trailing newline or formfeed characters. Any other control
characters in the text will also be sent as-is in the POST request.

Please be aware that Wget needs to know the size of the POST data in
advance.  Therefore the argument to @code{--post-file} must be a regular
file; specifying a FIFO or something like @file{/dev/stdin} won't work.
It's not quite clear how to work around this limitation inherent in
HTTP/1.0.  Although HTTP/1.1 introduces @dfn{chunked} transfer that
doesn't require knowing the request length in advance, a client can't
use chunked unless it knows it's talking to an HTTP/1.1 server.  And it
can't know that until it receives a response, which in turn requires the
request to have been completed -- a chicken-and-egg problem.

Note: As of version 1.15 if Wget is redirected after the POST request is
completed, its behaviour will depend on the response code returned by the
server.  In case of a 301 Moved Permanently, 302 Moved Temporarily or
307 Temporary Redirect, Wget will, in accordance with RFC2616, continue
to send a POST request.
In case a server wants the client to change the Request method upon
redirection, it should send a 303 See Other response code.

This example shows how to log in to a server using POST and then proceed to
download the desired pages, presumably only accessible to authorized
users:

@example
@group
# @r{Log in to the server.  This can be done only once.}
wget --save-cookies cookies.txt \
     --post-data 'user=foo&password=bar' \
     http://example.com/auth.php

# @r{Now grab the page or pages we care about.}
wget --load-cookies cookies.txt \
     -p http://example.com/interesting/article.php
@end group
@end example

If the server is using session cookies to track user authentication,
the above will not work because @samp{--save-cookies} will not save
them (and neither will browsers) and the @file{cookies.txt} file will
be empty.  In that case use @samp{--keep-session-cookies} along with
@samp{--save-cookies} to force saving of session cookies.

@cindex Other HTTP Methods
@item --method=@var{HTTP-Method}
For the purpose of RESTful scripting, Wget allows sending of other HTTP Methods
without the need to explicitly set them using @samp{--header=Header-Line}.
Wget will use whatever string is passed to it after @samp{--method} as the HTTP
Method to the server.

@item --body-data=@var{Data-String}
@itemx --body-file=@var{Data-File}
Must be set when additional data needs to be sent to the server along with the
Method specified using @samp{--method}.  @samp{--body-data} sends @var{string} as
data, whereas @samp{--body-file} sends the contents of @var{file}.  Other than that,
they work in exactly the same way.

Currently, @samp{--body-file} is @emph{not} for transmitting files as a whole.
Wget does not currently support @code{multipart/form-data} for transmitting data;
only @code{application/x-www-form-urlencoded}. In the future, this may be changed
so that wget sends the @samp{--body-file} as a complete file instead of sending its
contents to the server. Please be aware that Wget needs to know the contents of
BODY Data in advance, and hence the argument to @samp{--body-file} should be a
regular file. See @samp{--post-file} for a more detailed explanation.
Only one of @samp{--body-data} and @samp{--body-file} should be specified.

If Wget is redirected after the request is completed, Wget will
suspend the current method and send a GET request till the redirection
is completed.  This is true for all redirection response codes except
307 Temporary Redirect which is used to explicitly specify that the
request method should @emph{not} change.  Another exception is when
the method is set to @code{POST}, in which case the redirection rules
specified under @samp{--post-data} are followed.

@cindex Content-Disposition
@item --content-disposition

If this is set to on, experimental (not fully-functional) support for
@code{Content-Disposition} headers is enabled. This can currently result in
extra round-trips to the server for a @code{HEAD} request, and is known
to suffer from a few bugs, which is why it is not currently enabled by default.

This option is useful for some file-downloading CGI programs that use
@code{Content-Disposition} headers to describe what the name of a
downloaded file should be.

When combined with @samp{--metalink-over-http} and @samp{--trust-server-names},
a @samp{Content-Type: application/metalink4+xml} file is named using the
@code{Content-Disposition} filename field, if available.

@cindex Content On Error
@item --content-on-error

If this is set to on, wget will not skip the content when the server responds
with a http status code that indicates error.

@cindex Trust server names
@item --trust-server-names

If this is set, on a redirect, the local file name will be based
on the redirection URL.  By default the local file name is based on
the original URL.  When doing recursive retrieving this can be helpful
because in many web sites redirected URLs correspond to an underlying
file structure, while link URLs do not.

@cindex authentication
@item --auth-no-challenge

If this option is given, Wget will send Basic HTTP authentication
information (plaintext username and password) for all requests, just
like Wget 1.10.2 and prior did by default.

Use of this option is not recommended, and is intended only to support
some few obscure servers, which never send HTTP authentication
challenges, but accept unsolicited auth info, say, in addition to
form-based authentication.

@item --retry-on-host-error
Consider host errors, such as ``Temporary failure in name resolution'',
as non-fatal, transient errors.

@item --retry-on-http-error=@var{code[,code,...]}
Consider given HTTP response codes as non-fatal, transient errors.
Supply a comma-separated list of 3-digit HTTP response codes as
argument. Useful to work around special circumstances where retries
are required, but the server responds with an error code normally not
retried by Wget. Such errors might be 503 (Service Unavailable) and
429 (Too Many Requests). Retries enabled by this option are performed
subject to the normal retry timing and retry count limitations of
Wget.

Using this option is intended to support special use cases only and is
generally not recommended, as it can force retries even in cases where
the server is actually trying to decrease its load. Please use wisely
and only if you know what you are doing.

@end table

@node HTTPS (SSL/TLS) Options, FTP Options, HTTP Options, Invoking
@section HTTPS (SSL/TLS) Options

@cindex SSL
To support encrypted HTTP (HTTPS) downloads, Wget must be compiled
with an external SSL library. The current default is GnuTLS.
In addition, Wget also supports HSTS (HTTP Strict Transport Security).
If Wget is compiled without SSL support, none of these options are available.

@table @samp
@cindex SSL protocol, choose
@item --secure-protocol=@var{protocol}
Choose the secure protocol to be used.  Legal values are @samp{auto},
@samp{SSLv2}, @samp{SSLv3}, @samp{TLSv1}, @samp{TLSv1_1}, @samp{TLSv1_2},
@samp{TLSv1_3} and @samp{PFS}.  If @samp{auto} is used, the SSL library is
given the liberty of choosing the appropriate protocol automatically, which is
achieved by sending a TLSv1 greeting. This is the default.

Specifying @samp{SSLv2}, @samp{SSLv3}, @samp{TLSv1}, @samp{TLSv1_1},
@samp{TLSv1_2} or @samp{TLSv1_3} forces the use of the corresponding
protocol.  This is useful when talking to old and buggy SSL server
implementations that make it hard for the underlying SSL library to choose
the correct protocol version.  Fortunately, such servers are quite rare.

Specifying @samp{PFS} enforces the use of the so-called Perfect Forward
Security cipher suites. In short, PFS adds security by creating a one-time
key for each SSL connection. It has a bit more CPU impact on client and server.
We use known to be secure ciphers (e.g. no MD4) and the TLS protocol. This mode
also explicitly excludes non-PFS key exchange methods, such as RSA.

@item --https-only
When in recursive mode, only HTTPS links are followed.

@item --ciphers
Set the cipher list string. Typically this string sets the
cipher suites and other SSL/TLS options that the user wish should be used, in a
set order of preference (GnuTLS calls it 'priority string'). This string
will be fed verbatim to the SSL/TLS engine (OpenSSL or GnuTLS) and hence
its format and syntax is dependent on that. Wget will not process or manipulate it
in any way. Refer to the OpenSSL or GnuTLS documentation for more information.

@cindex SSL certificate, check
@item --no-check-certificate
Don't check the server certificate against the available certificate
authorities.  Also don't require the URL host name to match the common
name presented by the certificate.

As of Wget 1.10, the default is to verify the server's certificate
against the recognized certificate authorities, breaking the SSL
handshake and aborting the download if the verification fails.
Although this provides more secure downloads, it does break
interoperability with some sites that worked with previous Wget
versions, particularly those using self-signed, expired, or otherwise
invalid certificates.  This option forces an ``insecure'' mode of
operation that turns the certificate verification errors into warnings
and allows you to proceed.

If you encounter ``certificate verification'' errors or ones saying
that ``common name doesn't match requested host name'', you can use
this option to bypass the verification and proceed with the download.
@emph{Only use this option if you are otherwise convinced of the
site's authenticity, or if you really don't care about the validity of
its certificate.}  It is almost always a bad idea not to check the
certificates when transmitting confidential or important data.
For self-signed/internal certificates, you should download the certificate
and verify against that instead of forcing this insecure mode.
If you are really sure of not desiring any certificate verification, you
can specify --check-certificate=quiet to tell wget to not print any
warning about invalid certificates, albeit in most cases this is the
wrong thing to do.

@cindex SSL certificate
@item --certificate=@var{file}
Use the client certificate stored in @var{file}.  This is needed for
servers that are configured to require certificates from the clients
that connect to them.  Normally a certificate is not required and this
switch is optional.

@cindex SSL certificate type, specify
@item --certificate-type=@var{type}
Specify the type of the client certificate.  Legal values are
@samp{PEM} (assumed by default) and @samp{DER}, also known as
@samp{ASN1}.

@item --private-key=@var{file}
Read the private key from @var{file}.  This allows you to provide the
private key in a file separate from the certificate.

@item --private-key-type=@var{type}
Specify the type of the private key.  Accepted values are @samp{PEM}
(the default) and @samp{DER}.

@item --ca-certificate=@var{file}
Use @var{file} as the file with the bundle of certificate authorities
(``CA'') to verify the peers.  The certificates must be in PEM format.

Without this option Wget looks for CA certificates at the
system-specified locations, chosen at OpenSSL installation time.

@cindex SSL certificate authority
@item --ca-directory=@var{directory}
Specifies directory containing CA certificates in PEM format.  Each
file contains one CA certificate, and the file name is based on a hash
value derived from the certificate.  This is achieved by processing a
certificate directory with the @code{c_rehash} utility supplied with
OpenSSL.  Using @samp{--ca-directory} is more efficient than
@samp{--ca-certificate} when many certificates are installed because
it allows Wget to fetch certificates on demand.

Without this option Wget looks for CA certificates at the
system-specified locations, chosen at OpenSSL installation time.

@cindex SSL CRL, certificate revocation list
@item --crl-file=@var{file}
Specifies a CRL file in @var{file}.  This is needed for certificates
that have been revocated by the CAs.

@cindex SSL Public Key Pin
@item --pinnedpubkey=file/hashes
Tells wget to use the specified public key file (or hashes) to verify the peer.
This can be a path to a file which contains a single public key in PEM or DER
format, or any number of base64 encoded sha256 hashes preceded by ``sha256//''
and separated by ``;''

When negotiating a TLS or SSL connection, the server sends a certificate
indicating its identity. A public key is extracted from this certificate and if
it does not exactly match the public key(s) provided to this option, wget will
abort the connection before sending or receiving any data.

@cindex entropy, specifying source of
@cindex randomness, specifying source of
@item --random-file=@var{file}
[OpenSSL and LibreSSL only]
Use @var{file} as the source of random data for seeding the
pseudo-random number generator on systems without @file{/dev/urandom}.

On such systems the SSL library needs an external source of randomness
to initialize.  Randomness may be provided by EGD (see
@samp{--egd-file} below) or read from an external source specified by
the user.  If this option is not specified, Wget looks for random data
in @code{$RANDFILE} or, if that is unset, in @file{$HOME/.rnd}.

If you're getting the ``Could not seed OpenSSL PRNG; disabling SSL.'' 
error, you should provide random data using some of the methods
described above.

@cindex EGD
@item --egd-file=@var{file}
[OpenSSL only]
Use @var{file} as the EGD socket.  EGD stands for @dfn{Entropy
Gathering Daemon}, a user-space program that collects data from
various unpredictable system sources and makes it available to other
programs that might need it.  Encryption software, such as the SSL
library, needs sources of non-repeating randomness to seed the random
number generator used to produce cryptographically strong keys.

OpenSSL allows the user to specify his own source of entropy using the
@code{RAND_FILE} environment variable.  If this variable is unset, or
if the specified file does not produce enough randomness, OpenSSL will
read random data from EGD socket specified using this option.

If this option is not specified (and the equivalent startup command is
not used), EGD is never contacted.  EGD is not needed on modern Unix
systems that support @file{/dev/urandom}.

@cindex HSTS
@item --no-hsts
Wget supports HSTS (HTTP Strict Transport Security, RFC 6797) by default.
Use @samp{--no-hsts} to make Wget act as a non-HSTS-compliant UA. As a
consequence, Wget would ignore all the @code{Strict-Transport-Security}
headers, and would not enforce any existing HSTS policy.

@item --hsts-file=@var{file}
By default, Wget stores its HSTS database in @file{~/.wget-hsts}.
You can use @samp{--hsts-file} to override this. Wget will use
the supplied file as the HSTS database. Such file must conform to the
correct HSTS database format used by Wget. If Wget cannot parse the provided
file, the behaviour is unspecified.

The Wget's HSTS database is a plain text file. Each line contains an HSTS entry
(ie. a site that has issued a @code{Strict-Transport-Security} header and that
therefore has specified a concrete HSTS policy to be applied). Lines starting with
a dash (@code{#}) are ignored by Wget. Please note that in spite of this convenient
human-readability hand-hacking the HSTS database is generally not a good idea.

An HSTS entry line consists of several fields separated by one or more whitespace:

@code{<hostname> SP [<port>] SP <include subdomains> SP <created> SP <max-age>}

The @var{hostname} and @var{port} fields indicate the hostname and port to which
the given HSTS policy applies. The @var{port} field may be zero, and it will, in
most of the cases. That means that the port number will not be taken into account
when deciding whether such HSTS policy should be applied on a given request (only
the hostname will be evaluated). When @var{port} is different to zero, both the
target hostname and the port will be evaluated and the HSTS policy will only be applied
if both of them match. This feature has been included for testing/development purposes only.
The Wget testsuite (in @file{testenv/}) creates HSTS databases with explicit ports
with the purpose of ensuring Wget's correct behaviour. Applying HSTS policies to ports
other than the default ones is discouraged by RFC 6797 (see Appendix B "Differences
between HSTS Policy and Same-Origin Policy"). Thus, this functionality should not be used
in production environments and @var{port} will typically be zero. The last three fields
do what they are expected to. The field @var{include_subdomains} can either be @code{1}
or @code{0} and it signals whether the subdomains of the target domain should be
part of the given HSTS policy as well. The @var{created} and @var{max-age} fields
hold the timestamp values of when such entry was created (first seen by Wget) and the
HSTS-defined value 'max-age', which states how long should that HSTS policy remain active,
measured in seconds elapsed since the timestamp stored in @var{created}. Once that time
has passed, that HSTS policy will no longer be valid and will eventually be removed
from the database.

If you supply your own HSTS database via @samp{--hsts-file}, be aware that Wget
may modify the provided file if any change occurs between the HSTS policies
requested by the remote servers and those in the file. When Wget exits,
it effectively updates the HSTS database by rewriting the database file with the new entries.

If the supplied file does not exist, Wget will create one. This file will contain the new HSTS
entries. If no HSTS entries were generated (no @code{Strict-Transport-Security} headers
were sent by any of the servers) then no file will be created, not even an empty one. This
behaviour applies to the default database file (@file{~/.wget-hsts}) as well: it will not be
created until some server enforces an HSTS policy.

Care is taken not to override possible changes made by other Wget processes at
the same time over the HSTS database. Before dumping the updated HSTS entries
on the file, Wget will re-read it and merge the changes.

Using a custom HSTS database and/or modifying an existing one is discouraged.
For more information about the potential security threats arose from such practice,
see section 14 "Security Considerations" of RFC 6797, specially section 14.9
"Creative Manipulation of HSTS Policy Store".
@end table

@cindex WARC
@table @samp
@item --warc-file=@var{file}
Use @var{file} as the destination WARC file.

@item --warc-header=@var{string}
Use @var{string} into as the warcinfo record.

@item --warc-max-size=@var{size}
Set the maximum size of the WARC files to @var{size}.

@item --warc-cdx
Write CDX index files.

@item --warc-dedup=@var{file}
Do not store records listed in this CDX file.

@item --no-warc-compression
Do not compress WARC files with GZIP.

@item --no-warc-digests
Do not calculate SHA1 digests.

@item --no-warc-keep-log
Do not store the log file in a WARC record.

@item --warc-tempdir=@var{dir}
Specify the location for temporary files created by the WARC writer.
@end table

@node FTP Options, Recursive Retrieval Options, HTTPS (SSL/TLS) Options, Invoking
@section FTP Options

@table @samp
@cindex ftp user
@cindex ftp password
@cindex ftp authentication
@item --ftp-user=@var{user}
@itemx --ftp-password=@var{password}
Specify the username @var{user} and password @var{password} on an
@sc{ftp} server.  Without this, or the corresponding startup option, 
the password defaults to @samp{-wget@@}, normally used for anonymous 
FTP.

Another way to specify username and password is in the @sc{url} itself
(@pxref{URL Format}).  Either method reveals your password to anyone who
bothers to run @code{ps}.  To prevent the passwords from being seen,
store them in @file{.wgetrc} or @file{.netrc}, and make sure to protect
those files from other users with @code{chmod}.  If the passwords are
really important, do not leave them lying in those files either---edit
the files and delete them after Wget has started the download.

@iftex
@xref{Security Considerations}, for more information about security
issues with Wget.
@end iftex

@cindex .listing files, removing
@item --no-remove-listing
Don't remove the temporary @file{.listing} files generated by @sc{ftp}
retrievals.  Normally, these files contain the raw directory listings
received from @sc{ftp} servers.  Not removing them can be useful for
debugging purposes, or when you want to be able to easily check on the
contents of remote server directories (e.g. to verify that a mirror
you're running is complete).

Note that even though Wget writes to a known filename for this file,
this is not a security hole in the scenario of a user making
@file{.listing} a symbolic link to @file{/etc/passwd} or something and
asking @code{root} to run Wget in his or her directory.  Depending on
the options used, either Wget will refuse to write to @file{.listing},
making the globbing/recursion/time-stamping operation fail, or the
symbolic link will be deleted and replaced with the actual
@file{.listing} file, or the listing will be written to a
@file{.listing.@var{number}} file.

Even though this situation isn't a problem, though, @code{root} should
never run Wget in a non-trusted user's directory.  A user could do
something as simple as linking @file{index.html} to @file{/etc/passwd}
and asking @code{root} to run Wget with @samp{-N} or @samp{-r} so the file
will be overwritten.

@cindex globbing, toggle
@item --no-glob
Turn off @sc{ftp} globbing.  Globbing refers to the use of shell-like
special characters (@dfn{wildcards}), like @samp{*}, @samp{?}, @samp{[}
and @samp{]} to retrieve more than one file from the same directory at
once, like:

@example
wget ftp://gnjilux.srk.fer.hr/*.msg
@end example

By default, globbing will be turned on if the @sc{url} contains a
globbing character.  This option may be used to turn globbing on or off
permanently.

You may have to quote the @sc{url} to protect it from being expanded by
your shell.  Globbing makes Wget look for a directory listing, which is
system-specific.  This is why it currently works only with Unix @sc{ftp}
servers (and the ones emulating Unix @code{ls} output).

@cindex passive ftp
@item --no-passive-ftp
Disable the use of the @dfn{passive} FTP transfer mode.  Passive FTP
mandates that the client connect to the server to establish the data
connection rather than the other way around.

If the machine is connected to the Internet directly, both passive and
active FTP should work equally well.  Behind most firewall and NAT
configurations passive FTP has a better chance of working.  However,
in some rare firewall configurations, active FTP actually works when
passive FTP doesn't.  If you suspect this to be the case, use this
option, or set @code{passive_ftp=off} in your init file.

@cindex file permissions
@item --preserve-permissions
Preserve remote file permissions instead of permissions set by umask.

@cindex symbolic links, retrieving
@item --retr-symlinks
By default, when retrieving @sc{ftp} directories recursively and a symbolic link
is encountered, the symbolic link is traversed and the pointed-to files are
retrieved.  Currently, Wget does not traverse symbolic links to directories to
download them recursively, though this feature may be added in the future.

When @samp{--retr-symlinks=no} is specified, the linked-to file is not
downloaded.  Instead, a matching symbolic link is created on the local
file system.  The pointed-to file will not be retrieved unless this recursive
retrieval would have encountered it separately and downloaded it anyway.  This
option poses a security risk where a malicious FTP Server may cause Wget to
write to files outside of the intended directories through a specially crafted
@sc{.listing} file.

Note that when retrieving a file (not a directory) because it was
specified on the command-line, rather than because it was recursed to,
this option has no effect.  Symbolic links are always traversed in this
case.
@end table

@section FTPS Options

@table @samp
@item --ftps-implicit
This option tells Wget to use FTPS implicitly. Implicit FTPS consists of initializing
SSL/TLS from the very beginning of the control connection. This option does not send
an @code{AUTH TLS} command: it assumes the server speaks FTPS and directly starts an
SSL/TLS connection. If the attempt is successful, the session continues just like
regular FTPS (@code{PBSZ} and @code{PROT} are sent, etc.).
Implicit FTPS is no longer a requirement for FTPS implementations, and thus
many servers may not support it. If @samp{--ftps-implicit} is passed and no explicit
port number specified, the default port for implicit FTPS, 990, will be used, instead
of the default port for the "normal" (explicit) FTPS which is the same as that of FTP,
21.

@item --no-ftps-resume-ssl
Do not resume the SSL/TLS session in the data channel. When starting a data connection,
Wget tries to resume the SSL/TLS session previously started in the control connection.
SSL/TLS session resumption avoids performing an entirely new handshake by reusing
the SSL/TLS parameters of a previous session. Typically, the FTPS servers want it that way,
so Wget does this by default. Under rare circumstances however, one might want to
start an entirely new SSL/TLS session in every data connection.
This is what @samp{--no-ftps-resume-ssl} is for.

@item --ftps-clear-data-connection
All the data connections will be in plain text. Only the control connection will be
under SSL/TLS. Wget will send a @code{PROT C} command to achieve this, which must be
approved by the server.

@item --ftps-fallback-to-ftp
Fall back to FTP if FTPS is not supported by the target server. For security reasons,
this option is not asserted by default. The default behaviour is to exit with an error.
If a server does not successfully reply to the initial @code{AUTH TLS} command, or in the
case of implicit FTPS, if the initial SSL/TLS connection attempt is rejected, it is
considered that such server does not support FTPS.
@end table

@node Recursive Retrieval Options, Recursive Accept/Reject Options, FTP Options, Invoking
@section Recursive Retrieval Options

@table @samp
@item -r
@itemx --recursive
Turn on recursive retrieving.  @xref{Recursive Download}, for more
details.  The default maximum depth is 5.

@item -l @var{depth}
@itemx --level=@var{depth}
Set the maximum number of subdirectories that Wget will recurse into to @var{depth}.
In order to prevent one from accidentally downloading very large websites when using recursion
this is limited to a depth of 5 by default, i.e., it will traverse at most 5 directories deep
starting from the provided URL.
Set @samp{-l 0} or @samp{-l inf} for infinite recursion depth.

@example
wget -r -l 0 http://@var{site}/1.html
@end example

Ideally, one would expect this to download just @file{1.html}.
but unfortunately this is not the case, because @samp{-l 0} is equivalent to
@samp{-l inf}---that is, infinite recursion.  To download a single @sc{html}
page (or a handful of them), specify them all on the command line and leave away @samp{-r}
and @samp{-l}. To download the essential items to view a single @sc{html} page, see @samp{page requisites}.

@cindex proxy filling
@cindex delete after retrieval
@cindex filling proxy cache
@item --delete-after
This option tells Wget to delete every single file it downloads,
@emph{after} having done so.  It is useful for pre-fetching popular
pages through a proxy, e.g.:

@example
wget -r -nd --delete-after http://whatever.com/~popular/page/
@end example

The @samp{-r} option is to retrieve recursively, and @samp{-nd} to not
create directories.  

Note that @samp{--delete-after} deletes files on the local machine.  It
does not issue the @samp{DELE} command to remote FTP sites, for
instance.  Also note that when @samp{--delete-after} is specified,
@samp{--convert-links} is ignored, so @samp{.orig} files are simply not
created in the first place.

@cindex conversion of links
@cindex link conversion
@item -k
@itemx --convert-links
After the download is complete, convert the links in the document to
make them suitable for local viewing.  This affects not only the visible
hyperlinks, but any part of the document that links to external content,
such as embedded images, links to style sheets, hyperlinks to non-@sc{html}
content, etc.

Each link will be changed in one of the two ways:

@itemize @bullet
@item
The links to files that have been downloaded by Wget will be changed to
refer to the file they point to as a relative link.

Example: if the downloaded file @file{/foo/doc.html} links to
@file{/bar/img.gif}, also downloaded, then the link in @file{doc.html}
will be modified to point to @samp{../bar/img.gif}.  This kind of
transformation works reliably for arbitrary combinations of directories.

@item
The links to files that have not been downloaded by Wget will be changed
to include host name and absolute path of the location they point to.

Example: if the downloaded file @file{/foo/doc.html} links to
@file{/bar/img.gif} (or to @file{../bar/img.gif}), then the link in
@file{doc.html} will be modified to point to
@file{http://@var{hostname}/bar/img.gif}.
@end itemize

Because of this, local browsing works reliably: if a linked file was
downloaded, the link will refer to its local name; if it was not
downloaded, the link will refer to its full Internet address rather than
presenting a broken link.  The fact that the former links are converted
to relative links ensures that you can move the downloaded hierarchy to
another directory.

Note that only at the end of the download can Wget know which links have
been downloaded.  Because of that, the work done by @samp{-k} will be
performed at the end of all the downloads.

@item --convert-file-only
This option converts only the filename part of the URLs, leaving the rest
of the URLs untouched. This filename part is sometimes referred to as the
"basename", although we avoid that term here in order not to cause confusion.

It works particularly well in conjunction with @samp{--adjust-extension}, although
this coupling is not enforced. It proves useful to populate Internet caches
with files downloaded from different hosts.

Example: if some link points to @file{//foo.com/bar.cgi?xyz} with
@samp{--adjust-extension} asserted and its local destination is intended to be
@file{./foo.com/bar.cgi?xyz.css}, then the link would be converted to
@file{//foo.com/bar.cgi?xyz.css}. Note that only the filename part has been
modified. The rest of the URL has been left untouched, including the net path
(@code{//}) which would otherwise be processed by Wget and converted to the
effective scheme (ie. @code{http://}).

@cindex backing up converted files
@item -K
@itemx --backup-converted
When converting a file, back up the original version with a @samp{.orig}
suffix.  Affects the behavior of @samp{-N} (@pxref{HTTP Time-Stamping
Internals}).

@item -m
@itemx --mirror
Turn on options suitable for mirroring.  This option turns on recursion
and time-stamping, sets infinite recursion depth and keeps @sc{ftp}
directory listings.  It is currently equivalent to
@samp{-r -N -l inf --no-remove-listing}.

@cindex page requisites
@cindex required images, downloading
@item -p
@itemx --page-requisites
This option causes Wget to download all the files that are necessary to
properly display a given @sc{html} page.  This includes such things as
inlined images, sounds, and referenced stylesheets.

Ordinarily, when downloading a single @sc{html} page, any requisite documents
that may be needed to display it properly are not downloaded.  Using
@samp{-r} together with @samp{-l} can help, but since Wget does not
ordinarily distinguish between external and inlined documents, one is
generally left with ``leaf documents'' that are missing their
requisites.

For instance, say document @file{1.html} contains an @code{<IMG>} tag
referencing @file{1.gif} and an @code{<A>} tag pointing to external
document @file{2.html}.  Say that @file{2.html} is similar but that its
image is @file{2.gif} and it links to @file{3.html}.  Say this
continues up to some arbitrarily high number.

If one executes the command:

@example
wget -r -l 2 http://@var{site}/1.html
@end example

then @file{1.html}, @file{1.gif}, @file{2.html}, @file{2.gif}, and
@file{3.html} will be downloaded.  As you can see, @file{3.html} is
without its requisite @file{3.gif} because Wget is simply counting the
number of hops (up to 2) away from @file{1.html} in order to determine
where to stop the recursion.  However, with this command:

@example
wget -r -l 2 -p http://@var{site}/1.html
@end example

all the above files @emph{and} @file{3.html}'s requisite @file{3.gif}
will be downloaded.  Similarly,

@example
wget -r -l 1 -p http://@var{site}/1.html
@end example

will cause @file{1.html}, @file{1.gif}, @file{2.html}, and @file{2.gif}
to be downloaded.  One might think that:

@example
wget -r -l 0 -p http://@var{site}/1.html
@end example

would download just @file{1.html} and @file{1.gif}, but unfortunately
this is not the case, because @samp{-l 0} is equivalent to
@samp{-l inf}---that is, infinite recursion.  To download a single @sc{html}
page (or a handful of them, all specified on the command-line or in a
@samp{-i} @sc{url} input file) and its (or their) requisites, simply leave off
@samp{-r} and @samp{-l}:

@example
wget -p http://@var{site}/1.html
@end example

Note that Wget will behave as if @samp{-r} had been specified, but only
that single page and its requisites will be downloaded.  Links from that
page to external documents will not be followed.  Actually, to download
a single page and all its requisites (even if they exist on separate
websites), and make sure the lot displays properly locally, this author
likes to use a few options in addition to @samp{-p}:

@example
wget -E -H -k -K -p http://@var{site}/@var{document}
@end example

To finish off this topic, it's worth knowing that Wget's idea of an
external document link is any URL specified in an @code{<A>} tag, an
@code{<AREA>} tag, or a @code{<LINK>} tag other than @code{<LINK
REL="stylesheet">}.

@cindex @sc{html} comments
@cindex comments, @sc{html}
@item --strict-comments
Turn on strict parsing of @sc{html} comments.  The default is to terminate
comments at the first occurrence of @samp{-->}.

According to specifications, @sc{html} comments are expressed as @sc{sgml}
@dfn{declarations}.  Declaration is special markup that begins with
@samp{<!} and ends with @samp{>}, such as @samp{<!DOCTYPE ...>}, that
may contain comments between a pair of @samp{--} delimiters.  @sc{html}
comments are ``empty declarations'', @sc{sgml} declarations without any
non-comment text.  Therefore, @samp{<!--foo-->} is a valid comment, and
so is @samp{<!--one-- --two-->}, but @samp{<!--1--2-->} is not.

On the other hand, most @sc{html} writers don't perceive comments as anything
other than text delimited with @samp{<!--} and @samp{-->}, which is not
quite the same.  For example, something like @samp{<!------------>}
works as a valid comment as long as the number of dashes is a multiple
of four (!).  If not, the comment technically lasts until the next
@samp{--}, which may be at the other end of the document.  Because of
this, many popular browsers completely ignore the specification and
implement what users have come to expect: comments delimited with
@samp{<!--} and @samp{-->}.

Until version 1.9, Wget interpreted comments strictly, which resulted in
missing links in many web pages that displayed fine in browsers, but had
the misfortune of containing non-compliant comments.  Beginning with
version 1.9, Wget has joined the ranks of clients that implements
``naive'' comments, terminating each comment at the first occurrence of
@samp{-->}.

If, for whatever reason, you want strict comment parsing, use this
option to turn it on.
@end table

@node Recursive Accept/Reject Options, Exit Status, Recursive Retrieval Options, Invoking
@section Recursive Accept/Reject Options

@table @samp
@item -A @var{acclist} --accept @var{acclist}
@itemx -R @var{rejlist} --reject @var{rejlist}
Specify comma-separated lists of file name suffixes or patterns to
accept or reject (@pxref{Types of Files}). Note that if
any of the wildcard characters, @samp{*}, @samp{?}, @samp{[} or
@samp{]}, appear in an element of @var{acclist} or @var{rejlist},
it will be treated as a pattern, rather than a suffix.
In this case, you have to enclose the pattern into quotes to prevent
your shell from expanding it, like in @samp{-A "*.mp3"} or @samp{-A '*.mp3'}.

@item --accept-regex @var{urlregex}
@itemx --reject-regex @var{urlregex}
Specify a regular expression to accept or reject the complete URL.

@item --regex-type @var{regextype}
Specify the regular expression type.  Possible types are @samp{posix} or
@samp{pcre}.  Note that to be able to use @samp{pcre} type, wget has to be
compiled with libpcre support.

@item -D @var{domain-list}
@itemx --domains=@var{domain-list}
Set domains to be followed.  @var{domain-list} is a comma-separated list
of domains.  Note that it does @emph{not} turn on @samp{-H}.

@item --exclude-domains @var{domain-list}
Specify the domains that are @emph{not} to be followed
(@pxref{Spanning Hosts}).

@cindex follow FTP links
@item --follow-ftp
Follow @sc{ftp} links from @sc{html} documents.  Without this option,
Wget will ignore all the @sc{ftp} links.

@cindex tag-based recursive pruning
@item --follow-tags=@var{list}
Wget has an internal table of @sc{html} tag / attribute pairs that it
considers when looking for linked documents during a recursive
retrieval.  If a user wants only a subset of those tags to be
considered, however, he or she should be specify such tags in a
comma-separated @var{list} with this option.

@item --ignore-tags=@var{list}
This is the opposite of the @samp{--follow-tags} option.  To skip
certain @sc{html} tags when recursively looking for documents to download,
specify them in a comma-separated @var{list}.  

In the past, this option was the best bet for downloading a single page
and its requisites, using a command-line like:

@example
wget --ignore-tags=a,area -H -k -K -r http://@var{site}/@var{document}
@end example

However, the author of this option came across a page with tags like
@code{<LINK REL="home" HREF="/">} and came to the realization that
specifying tags to ignore was not enough.  One can't just tell Wget to
ignore @code{<LINK>}, because then stylesheets will not be downloaded.
Now the best bet for downloading a single page and its requisites is the
dedicated @samp{--page-requisites} option.

@cindex case fold
@cindex ignore case
@item --ignore-case
Ignore case when matching files and directories.  This influences the
behavior of -R, -A, -I, and -X options, as well as globbing
implemented when downloading from FTP sites.  For example, with this
option, @samp{-A "*.txt"} will match @samp{file1.txt}, but also
@samp{file2.TXT}, @samp{file3.TxT}, and so on.
The quotes in the example are to prevent the shell from expanding the
pattern.

@item -H
@itemx --span-hosts
Enable spanning across hosts when doing recursive retrieving
(@pxref{Spanning Hosts}).

@item -L
@itemx --relative
Follow relative links only.  Useful for retrieving a specific home page
without any distractions, not even those from the same hosts
(@pxref{Relative Links}).

@item -I @var{list}
@itemx --include-directories=@var{list}
Specify a comma-separated list of directories you wish to follow when
downloading (@pxref{Directory-Based Limits}).  Elements
of @var{list} may contain wildcards.

@item -X @var{list}
@itemx --exclude-directories=@var{list}
Specify a comma-separated list of directories you wish to exclude from
download (@pxref{Directory-Based Limits}).  Elements of
@var{list} may contain wildcards.

@item -np
@item --no-parent
Do not ever ascend to the parent directory when retrieving recursively.
This is a useful option, since it guarantees that only the files
@emph{below} a certain hierarchy will be downloaded.
@xref{Directory-Based Limits}, for more details.
@end table

@c man end

@node Exit Status,  , Recursive Accept/Reject Options, Invoking
@section Exit Status
                                   
@c man begin EXITSTATUS

Wget may return one of several error codes if it encounters problems.


@table @asis
@item 0
No problems occurred.

@item 1
Generic error code.

@item 2
Parse error---for instance, when parsing command-line options, the
@samp{.wgetrc} or @samp{.netrc}...

@item 3
File I/O error.

@item 4
Network failure.

@item 5
SSL verification failure.

@item 6
Username/password authentication failure.

@item 7
Protocol errors.

@item 8
Server issued an error response.
@end table


With the exceptions of 0 and 1, the lower-numbered exit codes take
precedence over higher-numbered ones, when multiple types of errors
are encountered.

In versions of Wget prior to 1.12, Wget's exit status tended to be
unhelpful and inconsistent. Recursive downloads would virtually always
return 0 (success), regardless of any issues encountered, and
non-recursive fetches only returned the status corresponding to the
most recently-attempted download.

@c man end

@node Recursive Download, Following Links, Invoking, Top
@chapter Recursive Download
@cindex recursion
@cindex retrieving
@cindex recursive download

GNU Wget is capable of traversing parts of the Web (or a single
@sc{http} or @sc{ftp} server), following links and directory structure.
We refer to this as to @dfn{recursive retrieval}, or @dfn{recursion}.

With @sc{http} @sc{url}s, Wget retrieves and parses the @sc{html} or
@sc{css} from the given @sc{url}, retrieving the files the document
refers to, through markup like @code{href} or @code{src}, or @sc{css}
@sc{uri} values specified using the @samp{url()} functional notation.
If the freshly downloaded file is also of type @code{text/html},
@code{application/xhtml+xml}, or @code{text/css}, it will be parsed
and followed further.

Recursive retrieval of @sc{http} and @sc{html}/@sc{css} content is
@dfn{breadth-first}.  This means that Wget first downloads the requested
document, then the documents linked from that document, then the
documents linked by them, and so on.  In other words, Wget first
downloads the documents at depth 1, then those at depth 2, and so on
until the specified maximum depth.

The maximum @dfn{depth} to which the retrieval may descend is specified
with the @samp{-l} option.  The default maximum depth is five layers.

When retrieving an @sc{ftp} @sc{url} recursively, Wget will retrieve all
the data from the given directory tree (including the subdirectories up
to the specified depth) on the remote server, creating its mirror image
locally.  @sc{ftp} retrieval is also limited by the @code{depth}
parameter.  Unlike @sc{http} recursion, @sc{ftp} recursion is performed
depth-first.

By default, Wget will create a local directory tree, corresponding to
the one found on the remote server.

Recursive retrieving can find a number of applications, the most
important of which is mirroring.  It is also useful for @sc{www}
presentations, and any other opportunities where slow network
connections should be bypassed by storing the files locally.

You should be warned that recursive downloads can overload the remote
servers.  Because of that, many administrators frown upon them and may
ban access from your site if they detect very fast downloads of big
amounts of content.  When downloading from Internet servers, consider
using the @samp{-w} option to introduce a delay between accesses to the
server.  The download will take a while longer, but the server
administrator will not be alarmed by your rudeness.

Of course, recursive download may cause problems on your machine.  If
left to run unchecked, it can easily fill up the disk.  If downloading
from local network, it can also take bandwidth on the system, as well as
consume memory and CPU.

Try to specify the criteria that match the kind of download you are
trying to achieve.  If you want to download only one page, use
@samp{--page-requisites} without any additional recursion.  If you want
to download things under one directory, use @samp{-np} to avoid
downloading things from other directories.  If you want to download all
the files from one directory, use @samp{-l 1} to make sure the recursion
depth never exceeds one.  @xref{Following Links}, for more information
about this.

Recursive retrieval should be used with care.  Don't say you were not
warned.

@node Following Links, Time-Stamping, Recursive Download, Top
@chapter Following Links
@cindex links
@cindex following links

When retrieving recursively, one does not wish to retrieve loads of
unnecessary data.  Most of the time the users bear in mind exactly what
they want to download, and want Wget to follow only specific links.

For example, if you wish to download the music archive from
@samp{fly.srk.fer.hr}, you will not want to download all the home pages
that happen to be referenced by an obscure part of the archive.

Wget possesses several mechanisms that allows you to fine-tune which
links it will follow.

@menu
* Spanning Hosts::              (Un)limiting retrieval based on host name.
* Types of Files::              Getting only certain files.
* Directory-Based Limits::      Getting only certain directories.
* Relative Links::              Follow relative links only.
* FTP Links::                   Following FTP links.
@end menu

@node Spanning Hosts, Types of Files, Following Links, Following Links
@section Spanning Hosts
@cindex spanning hosts
@cindex hosts, spanning

Wget's recursive retrieval normally refuses to visit hosts different
than the one you specified on the command line.  This is a reasonable
default; without it, every retrieval would have the potential to turn
your Wget into a small version of google.

However, visiting different hosts, or @dfn{host spanning,} is sometimes
a useful option.  Maybe the images are served from a different server.
Maybe you're mirroring a site that consists of pages interlinked between
three servers.  Maybe the server has two equivalent names, and the @sc{html}
pages refer to both interchangeably.

@table @asis
@item Span to any host---@samp{-H}

The @samp{-H} option turns on host spanning, thus allowing Wget's
recursive run to visit any host referenced by a link.  Unless sufficient
recursion-limiting criteria are applied depth, these foreign hosts will
typically link to yet more hosts, and so on until Wget ends up sucking
up much more data than you have intended.

@item Limit spanning to certain domains---@samp{-D}

The @samp{-D} option allows you to specify the domains that will be
followed, thus limiting the recursion only to the hosts that belong to
these domains.  Obviously, this makes sense only in conjunction with
@samp{-H}.  A typical example would be downloading the contents of
@samp{www.example.com}, but allowing downloads from
@samp{images.example.com}, etc.:

@example
wget -rH -Dexample.com http://www.example.com/
@end example

You can specify more than one address by separating them with a comma,
e.g. @samp{-Ddomain1.com,domain2.com}.

@item Keep download off certain domains---@samp{--exclude-domains}

If there are domains you want to exclude specifically, you can do it
with @samp{--exclude-domains}, which accepts the same type of arguments
of @samp{-D}, but will @emph{exclude} all the listed domains.  For
example, if you want to download all the hosts from @samp{foo.edu}
domain, with the exception of @samp{sunsite.foo.edu}, you can do it like
this:

@example
wget -rH -Dfoo.edu --exclude-domains sunsite.foo.edu \
    http://www.foo.edu/
@end example

@end table

@node Types of Files, Directory-Based Limits, Spanning Hosts, Following Links
@section Types of Files
@cindex types of files

When downloading material from the web, you will often want to restrict
the retrieval to only certain file types.  For example, if you are
interested in downloading @sc{gif}s, you will not be overjoyed to get
loads of PostScript documents, and vice versa.

Wget offers two options to deal with this problem.  Each option
description lists a short name, a long name, and the equivalent command
in @file{.wgetrc}.

@cindex accept wildcards
@cindex accept suffixes
@cindex wildcards, accept
@cindex suffixes, accept
@table @samp
@item -A @var{acclist}
@itemx --accept @var{acclist}
@itemx accept = @var{acclist}
@itemx --accept-regex @var{urlregex}
@itemx accept-regex = @var{urlregex}
The argument to @samp{--accept} option is a list of file suffixes or
patterns that Wget will download during recursive retrieval.  A suffix
is the ending part of a file, and consists of ``normal'' letters,
e.g. @samp{gif} or @samp{.jpg}.  A matching pattern contains shell-like
wildcards, e.g. @samp{books*} or @samp{zelazny*196[0-9]*}.

So, specifying @samp{wget -A gif,jpg} will make Wget download only the
files ending with @samp{gif} or @samp{jpg}, i.e. @sc{gif}s and
@sc{jpeg}s.  On the other hand, @samp{wget -A "zelazny*196[0-9]*"} will
download only files beginning with @samp{zelazny} and containing numbers
from 1960 to 1969 anywhere within.  Look up the manual of your shell for
a description of how pattern matching works.

Of course, any number of suffixes and patterns can be combined into a
comma-separated list, and given as an argument to @samp{-A}.

The argument to @samp{--accept-regex} option is a regular expression which
is matched against the complete URL.

@cindex reject wildcards
@cindex reject suffixes
@cindex wildcards, reject
@cindex suffixes, reject
@item -R @var{rejlist}
@itemx --reject @var{rejlist}
@itemx reject = @var{rejlist}
@itemx --reject-regex @var{urlregex}
@itemx reject-regex = @var{urlregex}
The @samp{--reject} option works the same way as @samp{--accept}, only
its logic is the reverse; Wget will download all files @emph{except} the
ones matching the suffixes (or patterns) in the list.

So, if you want to download a whole page except for the cumbersome
@sc{mpeg}s and @sc{.au} files, you can use @samp{wget -R mpg,mpeg,au}.
Analogously, to download all files except the ones beginning with
@samp{bjork}, use @samp{wget -R "bjork*"}.  The quotes are to prevent
expansion by the shell.
@end table

The argument to @samp{--accept-regex} option is a regular expression which
is matched against the complete URL.

@noindent
The @samp{-A} and @samp{-R} options may be combined to achieve even
better fine-tuning of which files to retrieve.  E.g. @samp{wget -A
"*zelazny*" -R .ps} will download all the files having @samp{zelazny} as
a part of their name, but @emph{not} the PostScript files.

Note that these two options do not affect the downloading of @sc{html}
files (as determined by a @samp{.htm} or @samp{.html} filename
prefix). This behavior may not be desirable for all users, and may be
changed for future versions of Wget.

Note, too, that query strings (strings at the end of a URL beginning
with a question mark (@samp{?}) are not included as part of the
filename for accept/reject rules, even though these will actually
contribute to the name chosen for the local file. It is expected that
a future version of Wget will provide an option to allow matching
against query strings.

Finally, it's worth noting that the accept/reject lists are matched
@emph{twice} against downloaded files: once against the URL's filename
portion, to determine if the file should be downloaded in the first
place; then, after it has been accepted and successfully downloaded,
the local file's name is also checked against the accept/reject lists
to see if it should be removed. The rationale was that, since
@samp{.htm} and @samp{.html} files are always downloaded regardless of
accept/reject rules, they should be removed @emph{after} being
downloaded and scanned for links, if they did match the accept/reject
lists. However, this can lead to unexpected results, since the local
filenames can differ from the original URL filenames in the following
ways, all of which can change whether an accept/reject rule matches:

@itemize @bullet
@item
If the local file already exists and @samp{--no-directories} was
specified, a numeric suffix will be appended to the original name.
@item
If @samp{--adjust-extension} was specified, the local filename might have
@samp{.html} appended to it. If Wget is invoked with @samp{-E -A.php},
a filename such as @samp{index.php} will match be accepted, but upon
download will be named @samp{index.php.html}, which no longer matches,
and so the file will be deleted.
@item
Query strings do not contribute to URL matching, but are included in
local filenames, and so @emph{do} contribute to filename matching.
@end itemize

@noindent
This behavior, too, is considered less-than-desirable, and may change
in a future version of Wget.

@node Directory-Based Limits, Relative Links, Types of Files, Following Links
@section Directory-Based Limits
@cindex directories
@cindex directory limits

Regardless of other link-following facilities, it is often useful to
place the restriction of what files to retrieve based on the directories
those files are placed in.  There can be many reasons for this---the
home pages may be organized in a reasonable directory structure; or some
directories may contain useless information, e.g. @file{/cgi-bin} or
@file{/dev} directories.

Wget offers three different options to deal with this requirement.  Each
option description lists a short name, a long name, and the equivalent
command in @file{.wgetrc}.

@cindex directories, include
@cindex include directories
@cindex accept directories
@table @samp
@item -I @var{list}
@itemx --include @var{list}
@itemx include_directories = @var{list}
@samp{-I} option accepts a comma-separated list of directories included
in the retrieval.  Any other directories will simply be ignored.  The
directories are absolute paths.

So, if you wish to download from @samp{http://host/people/bozo/}
following only links to bozo's colleagues in the @file{/people}
directory and the bogus scripts in @file{/cgi-bin}, you can specify:

@example
wget -I /people,/cgi-bin http://host/people/bozo/
@end example

@cindex directories, exclude
@cindex exclude directories
@cindex reject directories
@item -X @var{list}
@itemx --exclude @var{list}
@itemx exclude_directories = @var{list}
@samp{-X} option is exactly the reverse of @samp{-I}---this is a list of
directories @emph{excluded} from the download.  E.g. if you do not want
Wget to download things from @file{/cgi-bin} directory, specify @samp{-X
/cgi-bin} on the command line.

The same as with @samp{-A}/@samp{-R}, these two options can be combined
to get a better fine-tuning of downloading subdirectories.  E.g. if you
want to load all the files from @file{/pub} hierarchy except for
@file{/pub/worthless}, specify @samp{-I/pub -X/pub/worthless}.

@cindex no parent
@item -np
@itemx --no-parent
@itemx no_parent = on
The simplest, and often very useful way of limiting directories is
disallowing retrieval of the links that refer to the hierarchy
@dfn{above} than the beginning directory, i.e. disallowing ascent to the
parent directory/directories.

The @samp{--no-parent} option (short @samp{-np}) is useful in this case.
Using it guarantees that you will never leave the existing hierarchy.
Supposing you issue Wget with:

@example
wget -r --no-parent http://somehost/~luzer/my-archive/
@end example

You may rest assured that none of the references to
@file{/~his-girls-homepage/} or @file{/~luzer/all-my-mpegs/} will be
followed.  Only the archive you are interested in will be downloaded.
Essentially, @samp{--no-parent} is similar to
@samp{-I/~luzer/my-archive}, only it handles redirections in a more
intelligent fashion.

@strong{Note} that, for HTTP (and HTTPS), the trailing slash is very
important to @samp{--no-parent}. HTTP has no concept of a ``directory''---Wget
relies on you to indicate what's a directory and what isn't. In
@samp{http://foo/bar/}, Wget will consider @samp{bar} to be a
directory, while in @samp{http://foo/bar} (no trailing slash),
@samp{bar} will be considered a filename (so @samp{--no-parent} would be
meaningless, as its parent is @samp{/}).
@end table

@node Relative Links, FTP Links, Directory-Based Limits, Following Links
@section Relative Links
@cindex relative links

When @samp{-L} is turned on, only the relative links are ever followed.
Relative links are here defined those that do not refer to the web
server root.  For example, these links are relative:

@example
<a href="foo.gif">
<a href="foo/bar.gif">
<a href="../foo/bar.gif">
@end example

These links are not relative:

@example
<a href="/foo.gif">
<a href="/foo/bar.gif">
<a href="http://www.example.com/foo/bar.gif">
@end example

Using this option guarantees that recursive retrieval will not span
hosts, even without @samp{-H}.  In simple cases it also allows downloads
to ``just work'' without having to convert links.

This option is probably not very useful and might be removed in a future
release.

@node FTP Links,  , Relative Links, Following Links
@section Following FTP Links
@cindex following ftp links

The rules for @sc{ftp} are somewhat specific, as it is necessary for
them to be.  @sc{ftp} links in @sc{html} documents are often included
for purposes of reference, and it is often inconvenient to download them
by default.

To have @sc{ftp} links followed from @sc{html} documents, you need to
specify the @samp{--follow-ftp} option.  Having done that, @sc{ftp}
links will span hosts regardless of @samp{-H} setting.  This is logical,
as @sc{ftp} links rarely point to the same host where the @sc{http}
server resides.  For similar reasons, the @samp{-L} options has no
effect on such downloads.  On the other hand, domain acceptance
(@samp{-D}) and suffix rules (@samp{-A} and @samp{-R}) apply normally.

Also note that followed links to @sc{ftp} directories will not be
retrieved recursively further.

@node Time-Stamping, Startup File, Following Links, Top
@chapter Time-Stamping
@cindex time-stamping
@cindex timestamping
@cindex updating the archives
@cindex incremental updating

One of the most important aspects of mirroring information from the
Internet is updating your archives.

Downloading the whole archive again and again, just to replace a few
changed files is expensive, both in terms of wasted bandwidth and money,
and the time to do the update.  This is why all the mirroring tools
offer the option of incremental updating.

Such an updating mechanism means that the remote server is scanned in
search of @dfn{new} files.  Only those new files will be downloaded in
the place of the old ones.

A file is considered new if one of these two conditions are met:

@enumerate
@item
A file of that name does not already exist locally.

@item
A file of that name does exist, but the remote file was modified more
recently than the local file.
@end enumerate

To implement this, the program needs to be aware of the time of last
modification of both local and remote files.  We call this information the
@dfn{time-stamp} of a file.

The time-stamping in GNU Wget is turned on using @samp{--timestamping}
(@samp{-N}) option, or through @code{timestamping = on} directive in
@file{.wgetrc}.  With this option, for each file it intends to download,
Wget will check whether a local file of the same name exists.  If it
does, and the remote file is not newer, Wget will not download it.

If the local file does not exist, or the sizes of the files do not
match, Wget will download the remote file no matter what the time-stamps
say.

@menu
* Time-Stamping Usage::         
* HTTP Time-Stamping Internals::  
* FTP Time-Stamping Internals::  
@end menu

@node Time-Stamping Usage, HTTP Time-Stamping Internals, Time-Stamping, Time-Stamping
@section Time-Stamping Usage
@cindex time-stamping usage
@cindex usage, time-stamping

The usage of time-stamping is simple.  Say you would like to download a
file so that it keeps its date of modification.

@example
wget -S http://www.gnu.ai.mit.edu/
@end example

A simple @code{ls -l} shows that the timestamp on the local file equals
the state of the @code{Last-Modified} header, as returned by the server.
As you can see, the time-stamping info is preserved locally, even
without @samp{-N} (at least for @sc{http}).

Several days later, you would like Wget to check if the remote file has
changed, and download it if it has.

@example
wget -N http://www.gnu.ai.mit.edu/
@end example

Wget will ask the server for the last-modified date.  If the local file
has the same timestamp as the server, or a newer one, the remote file
will not be re-fetched.  However, if the remote file is more recent,
Wget will proceed to fetch it.

The same goes for @sc{ftp}.  For example:

@example
wget "ftp://ftp.ifi.uio.no/pub/emacs/gnus/*"
@end example

(The quotes around that URL are to prevent the shell from trying to
interpret the @samp{*}.)

After download, a local directory listing will show that the timestamps
match those on the remote server.  Reissuing the command with @samp{-N}
will make Wget re-fetch @emph{only} the files that have been modified
since the last download.

If you wished to mirror the GNU archive every week, you would use a
command like the following, weekly:

@example
wget --timestamping -r ftp://ftp.gnu.org/pub/gnu/
@end example

Note that time-stamping will only work for files for which the server
gives a timestamp.  For @sc{http}, this depends on getting a
@code{Last-Modified} header.  For @sc{ftp}, this depends on getting a
directory listing with dates in a format that Wget can parse
(@pxref{FTP Time-Stamping Internals}).

@node HTTP Time-Stamping Internals, FTP Time-Stamping Internals, Time-Stamping Usage, Time-Stamping
@section HTTP Time-Stamping Internals
@cindex http time-stamping

Time-stamping in @sc{http} is implemented by checking of the
@code{Last-Modified} header.  If you wish to retrieve the file
@file{foo.html} through @sc{http}, Wget will check whether
@file{foo.html} exists locally.  If it doesn't, @file{foo.html} will be
retrieved unconditionally.

If the file does exist locally, Wget will first check its local
time-stamp (similar to the way @code{ls -l} checks it), and then send a
@code{HEAD} request to the remote server, demanding the information on
the remote file.

The @code{Last-Modified} header is examined to find which file was
modified more recently (which makes it ``newer'').  If the remote file
is newer, it will be downloaded; if it is older, Wget will give
up.@footnote{As an additional check, Wget will look at the
@code{Content-Length} header, and compare the sizes; if they are not the
same, the remote file will be downloaded no matter what the time-stamp
says.}

When @samp{--backup-converted} (@samp{-K}) is specified in conjunction
with @samp{-N}, server file @samp{@var{X}} is compared to local file
@samp{@var{X}.orig}, if extant, rather than being compared to local file
@samp{@var{X}}, which will always differ if it's been converted by
@samp{--convert-links} (@samp{-k}).

Arguably, @sc{http} time-stamping should be implemented using the
@code{If-Modified-Since} request.

@node FTP Time-Stamping Internals,  , HTTP Time-Stamping Internals, Time-Stamping
@section FTP Time-Stamping Internals
@cindex ftp time-stamping

In theory, @sc{ftp} time-stamping works much the same as @sc{http}, only
@sc{ftp} has no headers---time-stamps must be ferreted out of directory
listings.

If an @sc{ftp} download is recursive or uses globbing, Wget will use the
@sc{ftp} @code{LIST} command to get a file listing for the directory
containing the desired file(s).  It will try to analyze the listing,
treating it like Unix @code{ls -l} output, extracting the time-stamps.
The rest is exactly the same as for @sc{http}.  Note that when
retrieving individual files from an @sc{ftp} server without using
globbing or recursion, listing files will not be downloaded (and thus
files will not be time-stamped) unless @samp{-N} is specified.

Assumption that every directory listing is a Unix-style listing may
sound extremely constraining, but in practice it is not, as many
non-Unix @sc{ftp} servers use the Unixoid listing format because most
(all?) of the clients understand it.  Bear in mind that @sc{rfc959}
defines no standard way to get a file list, let alone the time-stamps.
We can only hope that a future standard will define this.

Another non-standard solution includes the use of @code{MDTM} command
that is supported by some @sc{ftp} servers (including the popular
@code{wu-ftpd}), which returns the exact time of the specified file.
Wget may support this command in the future.

@node Startup File, Examples, Time-Stamping, Top
@chapter Startup File
@cindex startup file
@cindex wgetrc
@cindex .wgetrc
@cindex startup
@cindex .netrc

Once you know how to change default settings of Wget through command
line arguments, you may wish to make some of those settings permanent.
You can do that in a convenient way by creating the Wget startup
file---@file{.wgetrc}.

Besides @file{.wgetrc} is the ``main'' initialization file, it is
convenient to have a special facility for storing passwords.  Thus Wget
reads and interprets the contents of @file{$HOME/.netrc}, if it finds
it.  You can find @file{.netrc} format in your system manuals.

Wget reads @file{.wgetrc} upon startup, recognizing a limited set of
commands.

@menu
* Wgetrc Location::             Location of various wgetrc files.
* Wgetrc Syntax::               Syntax of wgetrc.
* Wgetrc Commands::             List of available commands.
* Sample Wgetrc::               A wgetrc example.
@end menu

@node Wgetrc Location, Wgetrc Syntax, Startup File, Startup File
@section Wgetrc Location
@cindex wgetrc location
@cindex location of wgetrc

When initializing, Wget will look for a @dfn{global} startup file,
@file{/usr/local/etc/wgetrc} by default (or some prefix other than
@file{/usr/local}, if Wget was not installed there) and read commands
from there, if it exists.

Then it will look for the user's file.  If the environmental variable
@code{WGETRC} is set, Wget will try to load that file.  Failing that, no
further attempts will be made.

If @code{WGETRC} is not set, Wget will try to load @file{$HOME/.wgetrc}.

The fact that user's settings are loaded after the system-wide ones
means that in case of collision user's wgetrc @emph{overrides} the
system-wide wgetrc (in @file{/usr/local/etc/wgetrc} by default).
Fascist admins, away!

@node Wgetrc Syntax, Wgetrc Commands, Wgetrc Location, Startup File
@section Wgetrc Syntax
@cindex wgetrc syntax
@cindex syntax of wgetrc

The syntax of a wgetrc command is simple:

@example
variable = value
@end example

The @dfn{variable} will also be called @dfn{command}.  Valid
@dfn{values} are different for different commands.

The commands are case-, underscore- and minus-insensitive.  Thus
@samp{DIr__PrefiX}, @samp{DIr-PrefiX} and @samp{dirprefix} are the same.
Empty lines, lines beginning with @samp{#} and lines containing white-space
only are discarded.

Commands that expect a comma-separated list will clear the list on an
empty command.  So, if you wish to reset the rejection list specified in
global @file{wgetrc}, you can do it with:

@example
reject =
@end example

@node Wgetrc Commands, Sample Wgetrc, Wgetrc Syntax, Startup File
@section Wgetrc Commands
@cindex wgetrc commands

The complete set of commands is listed below.  Legal values are listed
after the @samp{=}.  Simple Boolean values can be set or unset using
@samp{on} and @samp{off} or @samp{1} and @samp{0}.

Some commands take pseudo-arbitrary values.  @var{address} values can be
hostnames or dotted-quad IP addresses.  @var{n} can be any positive
integer, or @samp{inf} for infinity, where appropriate.  @var{string}
values can be any non-empty string.

Most of these commands have direct command-line equivalents.  Also, any
wgetrc command can be specified on the command line using the
@samp{--execute} switch (@pxref{Basic Startup Options}.)

@table @asis
@item accept/reject = @var{string}
Same as @samp{-A}/@samp{-R} (@pxref{Types of Files}).

@item add_hostdir = on/off
Enable/disable host-prefixed file names.  @samp{-nH} disables it.

@item ask_password = on/off
Prompt for a password for each connection established. Cannot be specified
when @samp{--password} is being used, because they are mutually
exclusive. Equivalent to @samp{--ask-password}.

@item auth_no_challenge = on/off
If this option is given, Wget will send Basic HTTP authentication
information (plaintext username and password) for all requests. See
@samp{--auth-no-challenge}.

@item background = on/off
Enable/disable going to background---the same as @samp{-b} (which
enables it).

@item backup_converted = on/off
Enable/disable saving pre-converted files with the suffix
@samp{.orig}---the same as @samp{-K} (which enables it).

@item backups = @var{number}
Use up to @var{number} backups for a file.  Backups are rotated by
adding an incremental counter that starts at @samp{1}.  The default is
@samp{0}.

@item base = @var{string}
Consider relative @sc{url}s in input files (specified via the
@samp{input} command or the @samp{--input-file}/@samp{-i} option,
together with @samp{force_html} or @samp{--force-html})
as being relative to @var{string}---the same as @samp{--base=@var{string}}.

@item bind_address = @var{address}
Bind to @var{address}, like the @samp{--bind-address=@var{address}}.

@item ca_certificate = @var{file}
Set the certificate authority bundle file to @var{file}.  The same
as @samp{--ca-certificate=@var{file}}.

@item ca_directory = @var{directory}
Set the directory used for certificate authorities.  The same as
@samp{--ca-directory=@var{directory}}.

@item cache = on/off
When set to off, disallow server-caching.  See the @samp{--no-cache}
option.

@item certificate = @var{file}
Set the client certificate file name to @var{file}.  The same as
@samp{--certificate=@var{file}}.

@item certificate_type = @var{string}
Specify the type of the client certificate, legal values being
@samp{PEM} (the default) and @samp{DER} (aka ASN1).  The same as
@samp{--certificate-type=@var{string}}.

@item check_certificate = on/off
If this is set to off, the server certificate is not checked against
the specified client authorities.  The default is ``on''.  The same as
@samp{--check-certificate}.

@item connect_timeout = @var{n}
Set the connect timeout---the same as @samp{--connect-timeout}.

@item content_disposition = on/off
Turn on recognition of the (non-standard) @samp{Content-Disposition}
HTTP header---if set to @samp{on}, the same as @samp{--content-disposition}.

@item trust_server_names = on/off
If set to on, construct the local file name from redirection URLs
rather than original URLs.

@item continue = on/off
If set to on, force continuation of preexistent partially retrieved
files.  See @samp{-c} before setting it.

@item convert_links = on/off
Convert non-relative links locally.  The same as @samp{-k}.

@item cookies = on/off
When set to off, disallow cookies.  See the @samp{--cookies} option.

@item cut_dirs = @var{n}
Ignore @var{n} remote directory components.  Equivalent to
@samp{--cut-dirs=@var{n}}.

@item debug = on/off
Debug mode, same as @samp{-d}.

@item default_page = @var{string}
Default page name---the same as @samp{--default-page=@var{string}}.

@item delete_after = on/off
Delete after download---the same as @samp{--delete-after}.

@item dir_prefix = @var{string}
Top of directory tree---the same as @samp{-P @var{string}}.

@item dirstruct = on/off
Turning dirstruct on or off---the same as @samp{-x} or @samp{-nd},
respectively.

@item dns_cache = on/off
Turn DNS caching on/off.  Since DNS caching is on by default, this
option is normally used to turn it off and is equivalent to
@samp{--no-dns-cache}.

@item dns_timeout = @var{n}
Set the DNS timeout---the same as @samp{--dns-timeout}.

@item domains = @var{string}
Same as @samp{-D} (@pxref{Spanning Hosts}).

@item dot_bytes = @var{n}
Specify the number of bytes ``contained'' in a dot, as seen throughout
the retrieval (1024 by default).  You can postfix the value with
@samp{k} or @samp{m}, representing kilobytes and megabytes,
respectively.  With dot settings you can tailor the dot retrieval to
suit your needs, or you can use the predefined @dfn{styles}
(@pxref{Download Options}).

@item dot_spacing = @var{n}
Specify the number of dots in a single cluster (10 by default).

@item dots_in_line = @var{n}
Specify the number of dots that will be printed in each line throughout
the retrieval (50 by default).

@item egd_file = @var{file}
Use @var{string} as the EGD socket file name.  The same as
@samp{--egd-file=@var{file}}.

@item exclude_directories = @var{string}
Specify a comma-separated list of directories you wish to exclude from
download---the same as @samp{-X @var{string}} (@pxref{Directory-Based
Limits}).

@item exclude_domains = @var{string}
Same as @samp{--exclude-domains=@var{string}} (@pxref{Spanning
Hosts}).

@item follow_ftp = on/off
Follow @sc{ftp} links from @sc{html} documents---the same as
@samp{--follow-ftp}.

@item follow_tags = @var{string}
Only follow certain @sc{html} tags when doing a recursive retrieval,
just like @samp{--follow-tags=@var{string}}.

@item force_html = on/off
If set to on, force the input filename to be regarded as an @sc{html}
document---the same as @samp{-F}.

@item ftp_password = @var{string}
Set your @sc{ftp} password to @var{string}.  Without this setting, the
password defaults to @samp{-wget@@}, which is a useful default for
anonymous @sc{ftp} access.

This command used to be named @code{passwd} prior to Wget 1.10.

@item ftp_proxy = @var{string}
Use @var{string} as @sc{ftp} proxy, instead of the one specified in
environment.

@item ftp_user = @var{string}
Set @sc{ftp} user to @var{string}.

This command used to be named @code{login} prior to Wget 1.10.

@item glob = on/off
Turn globbing on/off---the same as @samp{--glob} and @samp{--no-glob}.

@item header = @var{string}
Define a header for HTTP downloads, like using
@samp{--header=@var{string}}.

@item compression = @var{string}
Choose the compression type to be used.  Legal values are @samp{auto}
(the default), @samp{gzip}, and @samp{none}.  The same as
@samp{--compression=@var{string}}.

@item adjust_extension = on/off
Add a @samp{.html} extension to @samp{text/html} or
@samp{application/xhtml+xml} files that lack one, a @samp{.css}
extension to @samp{text/css} files that lack one, and a @samp{.br},
@samp{.Z}, @samp{.zlib} or @samp{.gz} to compressed files like
@samp{-E}. Previously named @samp{html_extension} (still acceptable,
but deprecated).

@item http_keep_alive = on/off
Turn the keep-alive feature on or off (defaults to on).  Turning it
off is equivalent to @samp{--no-http-keep-alive}.

@item http_password = @var{string}
Set @sc{http} password, equivalent to
@samp{--http-password=@var{string}}.

@item http_proxy = @var{string}
Use @var{string} as @sc{http} proxy, instead of the one specified in
environment.

@item http_user = @var{string}
Set @sc{http} user to @var{string}, equivalent to
@samp{--http-user=@var{string}}.

@item https_only = on/off
When in recursive mode, only HTTPS links are followed (defaults to off).

@item https_proxy = @var{string}
Use @var{string} as @sc{https} proxy, instead of the one specified in
environment.

@item ignore_case = on/off
When set to on, match files and directories case insensitively; the
same as @samp{--ignore-case}.

@item ignore_length = on/off
When set to on, ignore @code{Content-Length} header; the same as
@samp{--ignore-length}.

@item ignore_tags = @var{string}
Ignore certain @sc{html} tags when doing a recursive retrieval, like
@samp{--ignore-tags=@var{string}}.

@item include_directories = @var{string}
Specify a comma-separated list of directories you wish to follow when
downloading---the same as @samp{-I @var{string}}.

@item iri = on/off
When set to on, enable internationalized URI (IRI) support; the same as
@samp{--iri}.

@item inet4_only = on/off
Force connecting to IPv4 addresses, off by default.  You can put this
in the global init file to disable Wget's attempts to resolve and
connect to IPv6 hosts.  Available only if Wget was compiled with IPv6
support.  The same as @samp{--inet4-only} or @samp{-4}.

@item inet6_only = on/off
Force connecting to IPv6 addresses, off by default.  Available only if
Wget was compiled with IPv6 support.  The same as @samp{--inet6-only}
or @samp{-6}.

@item input = @var{file}
Read the @sc{url}s from @var{string}, like @samp{-i @var{file}}.

@item keep_session_cookies = on/off
When specified, causes @samp{save_cookies = on} to also save session
cookies.  See @samp{--keep-session-cookies}.

@item limit_rate = @var{rate}
Limit the download speed to no more than @var{rate} bytes per second.
The same as @samp{--limit-rate=@var{rate}}.

@item load_cookies = @var{file}
Load cookies from @var{file}.  See @samp{--load-cookies @var{file}}.

@item local_encoding = @var{encoding}
Force Wget to use @var{encoding} as the default system encoding. See
@samp{--local-encoding}.

@item logfile = @var{file}
Set logfile to @var{file}, the same as @samp{-o @var{file}}.

@item max_redirect = @var{number}
Specifies the maximum number of redirections to follow for a resource.
See @samp{--max-redirect=@var{number}}.

@item mirror = on/off
Turn mirroring on/off.  The same as @samp{-m}.

@item netrc = on/off
Turn reading netrc on or off.

@item no_clobber = on/off
Same as @samp{-nc}.

@item no_parent = on/off
Disallow retrieving outside the directory hierarchy, like
@samp{--no-parent} (@pxref{Directory-Based Limits}).

@item no_proxy = @var{string}
Use @var{string} as the comma-separated list of domains to avoid in
proxy loading, instead of the one specified in environment.

@item output_document = @var{file}
Set the output filename---the same as @samp{-O @var{file}}.

@item page_requisites = on/off
Download all ancillary documents necessary for a single @sc{html} page to
display properly---the same as @samp{-p}.

@item passive_ftp = on/off
Change setting of passive @sc{ftp}, equivalent to the
@samp{--passive-ftp} option.

@item password = @var{string}
Specify password @var{string} for both @sc{ftp} and @sc{http} file retrieval. 
This command can be overridden using the @samp{ftp_password} and 
@samp{http_password} command for @sc{ftp} and @sc{http} respectively.

@item post_data = @var{string}
Use POST as the method for all HTTP requests and send @var{string} in
the request body.  The same as @samp{--post-data=@var{string}}.

@item post_file = @var{file}
Use POST as the method for all HTTP requests and send the contents of
@var{file} in the request body.  The same as
@samp{--post-file=@var{file}}.

@item prefer_family = none/IPv4/IPv6
When given a choice of several addresses, connect to the addresses
with specified address family first.  The address order returned by
DNS is used without change by default.  The same as @samp{--prefer-family},
which see for a detailed discussion of why this is useful.

@item private_key = @var{file}
Set the private key file to @var{file}.  The same as
@samp{--private-key=@var{file}}.

@item private_key_type = @var{string}
Specify the type of the private key, legal values being @samp{PEM}
(the default) and @samp{DER} (aka ASN1).  The same as
@samp{--private-type=@var{string}}.

@item progress = @var{string}
Set the type of the progress indicator.  Legal types are @samp{dot}
and @samp{bar}.  Equivalent to @samp{--progress=@var{string}}.

@item protocol_directories = on/off
When set, use the protocol name as a directory component of local file
names.  The same as @samp{--protocol-directories}.

@item proxy_password = @var{string}
Set proxy authentication password to @var{string}, like
@samp{--proxy-password=@var{string}}.

@item proxy_user = @var{string}
Set proxy authentication user name to @var{string}, like
@samp{--proxy-user=@var{string}}.

@item quiet = on/off
Quiet mode---the same as @samp{-q}.

@item quota = @var{quota}
Specify the download quota, which is useful to put in the global
@file{wgetrc}.  When download quota is specified, Wget will stop
retrieving after the download sum has become greater than quota.  The
quota can be specified in bytes (default), kbytes @samp{k} appended) or
mbytes (@samp{m} appended).  Thus @samp{quota = 5m} will set the quota
to 5 megabytes.  Note that the user's startup file overrides system
settings.

@item random_file = @var{file}
Use @var{file} as a source of randomness on systems lacking
@file{/dev/random}.

@item random_wait = on/off
Turn random between-request wait times on or off. The same as 
@samp{--random-wait}.

@item read_timeout = @var{n}
Set the read (and write) timeout---the same as
@samp{--read-timeout=@var{n}}.

@item reclevel = @var{n}
Recursion level (depth)---the same as @samp{-l @var{n}}.

@item recursive = on/off
Recursive on/off---the same as @samp{-r}.

@item referer = @var{string}
Set HTTP @samp{Referer:} header just like
@samp{--referer=@var{string}}.  (Note that it was the folks who wrote
the @sc{http} spec who got the spelling of ``referrer'' wrong.)

@item relative_only = on/off
Follow only relative links---the same as @samp{-L} (@pxref{Relative
Links}).

@item remote_encoding = @var{encoding}
Force Wget to use @var{encoding} as the default remote server encoding.
See @samp{--remote-encoding}.

@item remove_listing = on/off
If set to on, remove @sc{ftp} listings downloaded by Wget.  Setting it
to off is the same as @samp{--no-remove-listing}.

@item restrict_file_names = unix/windows
Restrict the file names generated by Wget from URLs.  See
@samp{--restrict-file-names} for a more detailed description.

@item retr_symlinks = on/off
When set to on, retrieve symbolic links as if they were plain files; the
same as @samp{--retr-symlinks}.

@item retry_connrefused = on/off
When set to on, consider ``connection refused'' a transient
error---the same as @samp{--retry-connrefused}.

@item robots = on/off
Specify whether the norobots convention is respected by Wget, ``on'' by
default.  This switch controls both the @file{/robots.txt} and the
@samp{nofollow} aspect of the spec.  @xref{Robot Exclusion}, for more
details about this.  Be sure you know what you are doing before turning
this off.

@item save_cookies = @var{file}
Save cookies to @var{file}.  The same as @samp{--save-cookies
@var{file}}.

@item save_headers = on/off
Same as @samp{--save-headers}.

@item secure_protocol = @var{string}
Choose the secure protocol to be used.  Legal values are @samp{auto}
(the default), @samp{SSLv2}, @samp{SSLv3}, and @samp{TLSv1}.  The same
as @samp{--secure-protocol=@var{string}}.

@item server_response = on/off
Choose whether or not to print the @sc{http} and @sc{ftp} server
responses---the same as @samp{-S}.

@item show_all_dns_entries = on/off
When a DNS name is resolved, show all the IP addresses, not just the first
three.

@item span_hosts = on/off
Same as @samp{-H}.

@item spider = on/off
Same as @samp{--spider}.

@item strict_comments = on/off
Same as @samp{--strict-comments}.

@item timeout = @var{n}
Set all applicable timeout values to @var{n}, the same as @samp{-T
@var{n}}.

@item timestamping = on/off
Turn timestamping on/off.  The same as @samp{-N} (@pxref{Time-Stamping}).

@item use_server_timestamps = on/off
If set to @samp{off}, Wget won't set the local file's timestamp by the
one on the server (same as @samp{--no-use-server-timestamps}).

@item tries = @var{n}
Set number of retries per @sc{url}---the same as @samp{-t @var{n}}.

@item use_proxy = on/off
When set to off, don't use proxy even when proxy-related environment
variables are set.  In that case it is the same as using
@samp{--no-proxy}.

@item user = @var{string}
Specify username @var{string} for both @sc{ftp} and @sc{http} file retrieval. 
This command can be overridden using the @samp{ftp_user} and 
@samp{http_user} command for @sc{ftp} and @sc{http} respectively.

@item user_agent = @var{string}
User agent identification sent to the HTTP Server---the same as
@samp{--user-agent=@var{string}}.

@item verbose = on/off
Turn verbose on/off---the same as @samp{-v}/@samp{-nv}.

@item wait = @var{n}
Wait @var{n} seconds between retrievals---the same as @samp{-w
@var{n}}.

@item wait_retry = @var{n}
Wait up to @var{n} seconds between retries of failed retrievals
only---the same as @samp{--waitretry=@var{n}}.  Note that this is
turned on by default in the global @file{wgetrc}.
@end table

@node Sample Wgetrc,  , Wgetrc Commands, Startup File
@section Sample Wgetrc
@cindex sample wgetrc

This is the sample initialization file, as given in the distribution.
It is divided in two section---one for global usage (suitable for global
startup file), and one for local usage (suitable for
@file{$HOME/.wgetrc}).  Be careful about the things you change.

Note that almost all the lines are commented out.  For a command to have
any effect, you must remove the @samp{#} character at the beginning of
its line.

@example
@include sample.wgetrc.munged_for_texi_inclusion
@end example

@node Examples, Various, Startup File, Top
@chapter Examples
@cindex examples

@c man begin EXAMPLES
The examples are divided into three sections loosely based on their
complexity.

@menu
* Simple Usage::                Simple, basic usage of the program.
* Advanced Usage::              Advanced tips.
* Very Advanced Usage::         The hairy stuff.
@end menu

@node Simple Usage, Advanced Usage, Examples, Examples
@section Simple Usage

@itemize @bullet
@item
Say you want to download a @sc{url}.  Just type:

@example
wget http://fly.srk.fer.hr/
@end example

@item
But what will happen if the connection is slow, and the file is lengthy?
The connection will probably fail before the whole file is retrieved,
more than once.  In this case, Wget will try getting the file until it
either gets the whole of it, or exceeds the default number of retries
(this being 20).  It is easy to change the number of tries to 45, to
insure that the whole file will arrive safely:

@example
wget --tries=45 http://fly.srk.fer.hr/jpg/flyweb.jpg
@end example

@item
Now let's leave Wget to work in the background, and write its progress
to log file @file{log}.  It is tiring to type @samp{--tries}, so we
shall use @samp{-t}.

@example
wget -t 45 -o log http://fly.srk.fer.hr/jpg/flyweb.jpg &
@end example

The ampersand at the end of the line makes sure that Wget works in the
background.  To unlimit the number of retries, use @samp{-t inf}.

@item
The usage of @sc{ftp} is as simple.  Wget will take care of login and
password.

@example
wget ftp://gnjilux.srk.fer.hr/welcome.msg
@end example

@item
If you specify a directory, Wget will retrieve the directory listing,
parse it and convert it to @sc{html}.  Try:

@example
wget ftp://ftp.gnu.org/pub/gnu/
links index.html
@end example
@end itemize

@node Advanced Usage, Very Advanced Usage, Simple Usage, Examples
@section Advanced Usage

@itemize @bullet
@item
You have a file that contains the URLs you want to download?  Use the
@samp{-i} switch:

@example
wget -i @var{file}
@end example

If you specify @samp{-} as file name, the @sc{url}s will be read from
standard input.

@item
Create a five levels deep mirror image of the GNU web site, with the
same directory structure the original has, with only one try per
document, saving the log of the activities to @file{gnulog}:

@example
wget -r https://www.gnu.org/ -o gnulog
@end example

@item
The same as the above, but convert the links in the downloaded files to
point to local files, so you can view the documents off-line:

@example
wget --convert-links -r https://www.gnu.org/ -o gnulog
@end example

@item
Retrieve only one @sc{html} page, but make sure that all the elements needed
for the page to be displayed, such as inline images and external style
sheets, are also downloaded.  Also make sure the downloaded page
references the downloaded links.

@example
wget -p --convert-links http://www.example.com/dir/page.html
@end example

The @sc{html} page will be saved to @file{www.example.com/dir/page.html}, and
the images, stylesheets, etc., somewhere under @file{www.example.com/},
depending on where they were on the remote server.

@item
The same as the above, but without the @file{www.example.com/} directory.
In fact, I don't want to have all those random server directories
anyway---just save @emph{all} those files under a @file{download/}
subdirectory of the current directory.

@example
wget -p --convert-links -nH -nd -Pdownload \
     http://www.example.com/dir/page.html
@end example

@item
Retrieve the index.html of @samp{www.lycos.com}, showing the original
server headers:

@example
wget -S http://www.lycos.com/
@end example

@item
Save the server headers with the file, perhaps for post-processing.

@example
wget --save-headers http://www.lycos.com/
more index.html
@end example

@item
Retrieve the first two levels of @samp{wuarchive.wustl.edu}, saving them
to @file{/tmp}.

@example
wget -r -l2 -P/tmp ftp://wuarchive.wustl.edu/
@end example

@item
You want to download all the @sc{gif}s from a directory on an @sc{http}
server.  You tried @samp{wget http://www.example.com/dir/*.gif}, but that
didn't work because @sc{http} retrieval does not support globbing.  In
that case, use:

@example
wget -r -l1 --no-parent -A.gif http://www.example.com/dir/
@end example

More verbose, but the effect is the same.  @samp{-r -l1} means to
retrieve recursively (@pxref{Recursive Download}), with maximum depth
of 1.  @samp{--no-parent} means that references to the parent directory
are ignored (@pxref{Directory-Based Limits}), and @samp{-A.gif} means to
download only the @sc{gif} files.  @samp{-A "*.gif"} would have worked
too.

@item
Suppose you were in the middle of downloading, when Wget was
interrupted.  Now you do not want to clobber the files already present.
It would be:

@example
wget -nc -r https://www.gnu.org/
@end example

@item
If you want to encode your own username and password to @sc{http} or
@sc{ftp}, use the appropriate @sc{url} syntax (@pxref{URL Format}).

@example
wget ftp://hniksic:mypassword@@unix.example.com/.emacs
@end example

Note, however, that this usage is not advisable on multi-user systems
because it reveals your password to anyone who looks at the output of
@code{ps}.

@cindex redirecting output
@item
You would like the output documents to go to standard output instead of
to files?

@example
wget -O - http://jagor.srce.hr/ http://www.srce.hr/
@end example

You can also combine the two options and make pipelines to retrieve the
documents from remote hotlists:

@example
wget -O - http://cool.list.com/ | wget --force-html -i -
@end example
@end itemize

@node Very Advanced Usage,  , Advanced Usage, Examples
@section Very Advanced Usage

@cindex mirroring
@itemize @bullet
@item
If you wish Wget to keep a mirror of a page (or @sc{ftp}
subdirectories), use @samp{--mirror} (@samp{-m}), which is the shorthand
for @samp{-r -l inf -N}.  You can put Wget in the crontab file asking it
to recheck a site each Sunday:

@example
crontab
0 0 * * 0 wget --mirror https://www.gnu.org/ -o /home/me/weeklog
@end example

@item
In addition to the above, you want the links to be converted for local
viewing.  But, after having read this manual, you know that link
conversion doesn't play well with timestamping, so you also want Wget to
back up the original @sc{html} files before the conversion.  Wget invocation
would look like this:

@example
wget --mirror --convert-links --backup-converted  \
     https://www.gnu.org/ -o /home/me/weeklog
@end example

@item
But you've also noticed that local viewing doesn't work all that well
when @sc{html} files are saved under extensions other than @samp{.html},
perhaps because they were served as @file{index.cgi}.  So you'd like
Wget to rename all the files served with content-type @samp{text/html}
or @samp{application/xhtml+xml} to @file{@var{name}.html}.

@example
wget --mirror --convert-links --backup-converted \
     --adjust-extension -o /home/me/weeklog      \
     https://www.gnu.org/
@end example

Or, with less typing:

@example
wget -m -k -K -E https://www.gnu.org/ -o /home/me/weeklog
@end example
@end itemize
@c man end

@node Various, Appendices, Examples, Top
@chapter Various
@cindex various

This chapter contains all the stuff that could not fit anywhere else.

@menu
* Proxies::                     Support for proxy servers.
* Distribution::                Getting the latest version.
* Web Site::                    GNU Wget's presence on the World Wide Web.
* Mailing Lists::               Wget mailing list for announcements and discussion.
* Internet Relay Chat::         Wget's presence on IRC.
* Reporting Bugs::              How and where to report bugs.
* Portability::                 The systems Wget works on.
* Signals::                     Signal-handling performed by Wget.
@end menu

@node Proxies, Distribution, Various, Various
@section Proxies
@cindex proxies

@dfn{Proxies} are special-purpose @sc{http} servers designed to transfer
data from remote servers to local clients.  One typical use of proxies
is lightening network load for users behind a slow connection.  This is
achieved by channeling all @sc{http} and @sc{ftp} requests through the
proxy which caches the transferred data.  When a cached resource is
requested again, proxy will return the data from cache.  Another use for
proxies is for companies that separate (for security reasons) their
internal networks from the rest of Internet.  In order to obtain
information from the Web, their users connect and retrieve remote data
using an authorized proxy.

@c man begin ENVIRONMENT
Wget supports proxies for both @sc{http} and @sc{ftp} retrievals.  The
standard way to specify proxy location, which Wget recognizes, is using
the following environment variables:

@table @env
@item http_proxy
@itemx https_proxy
If set, the @env{http_proxy} and @env{https_proxy} variables should
contain the @sc{url}s of the proxies for @sc{http} and @sc{https}
connections respectively.

@item ftp_proxy
This variable should contain the @sc{url} of the proxy for @sc{ftp}
connections.  It is quite common that @env{http_proxy} and
@env{ftp_proxy} are set to the same @sc{url}.

@item no_proxy
This variable should contain a comma-separated list of domain extensions
proxy should @emph{not} be used for.  For instance, if the value of
@env{no_proxy} is @samp{.mit.edu}, proxy will not be used to retrieve
documents from MIT.
@end table
@c man end

In addition to the environment variables, proxy location and settings
may be specified from within Wget itself.

@table @samp
@item --no-proxy
@itemx proxy = on/off
This option and the corresponding command may be used to suppress the
use of proxy, even if the appropriate environment variables are set.

@item http_proxy = @var{URL}
@itemx https_proxy = @var{URL}
@itemx ftp_proxy = @var{URL}
@itemx no_proxy = @var{string}
These startup file variables allow you to override the proxy settings
specified by the environment.
@end table

Some proxy servers require authorization to enable you to use them.  The
authorization consists of @dfn{username} and @dfn{password}, which must
be sent by Wget.  As with @sc{http} authorization, several
authentication schemes exist.  For proxy authorization only the
@code{Basic} authentication scheme is currently implemented.

You may specify your username and password either through the proxy
@sc{url} or through the command-line options.  Assuming that the
company's proxy is located at @samp{proxy.company.com} at port 8001, a
proxy @sc{url} location containing authorization data might look like
this:

@example
http://hniksic:mypassword@@proxy.company.com:8001/
@end example

Alternatively, you may use the @samp{proxy-user} and
@samp{proxy-password} options, and the equivalent @file{.wgetrc}
settings @code{proxy_user} and @code{proxy_password} to set the proxy
username and password.

@node Distribution, Web Site, Proxies, Various
@section Distribution
@cindex latest version

Like all GNU utilities, the latest version of Wget can be found at the
master GNU archive site ftp.gnu.org, and its mirrors.  For example,
Wget @value{VERSION} can be found at
@url{https://ftp.gnu.org/pub/gnu/wget/wget-@value{VERSION}.tar.gz}

@node Web Site, Mailing Lists, Distribution, Various
@section Web Site
@cindex web site

The official web site for GNU Wget is at
@url{https//www.gnu.org/software/wget/}. However, most useful
information resides at ``The Wget Wgiki'',
@url{http://wget.addictivecode.org/}.

@node Mailing Lists, Internet Relay Chat, Web Site, Various
@section Mailing Lists
@cindex mailing list
@cindex list

@unnumberedsubsec Primary List

The primary mailinglist for discussion, bug-reports, or questions
about GNU Wget is at @email{bug-wget@@gnu.org}. To subscribe, send an
email to @email{bug-wget-join@@gnu.org}, or visit
@url{https://lists.gnu.org/mailman/listinfo/bug-wget}.

You do not need to subscribe to send a message to the list; however,
please note that unsubscribed messages are moderated, and may take a
while before they hit the list---@strong{usually around a day}.  If
you want your message to show up immediately, please subscribe to the
list before posting. Archives for the list may be found at
@url{https://lists.gnu.org/archive/html/bug-wget/}.

An NNTP/Usenettish gateway is also available via
@uref{http://gmane.org/about.php,Gmane}. You can see the Gmane
archives at
@url{http://news.gmane.org/gmane.comp.web.wget.general}. Note that the
Gmane archives conveniently include messages from both the current
list, and the previous one. Messages also show up in the Gmane
archives sooner than they do at @url{https://lists.gnu.org}.

@unnumberedsubsec Obsolete Lists

Previously, the mailing list @email{wget@@sunsite.dk} was used as the
main discussion list, and another list,
@email{wget-patches@@sunsite.dk} was used for submitting and
discussing patches to GNU Wget.

Messages from @email{wget@@sunsite.dk} are archived at
@itemize @tie{}
@item
@url{https://www.mail-archive.com/wget%40sunsite.dk/} and at
@item
@url{http://news.gmane.org/gmane.comp.web.wget.general} (which also
continues to archive the current list, @email{bug-wget@@gnu.org}).
@end itemize

Messages from @email{wget-patches@@sunsite.dk} are archived at
@itemize @tie{}
@item
@url{http://news.gmane.org/gmane.comp.web.wget.patches}.
@end itemize

@node Internet Relay Chat, Reporting Bugs, Mailing Lists, Various
@section Internet Relay Chat
@cindex Internet Relay Chat
@cindex IRC
@cindex #wget

In addition to the mailinglists, we also have a support channel set up
via IRC at @code{irc.freenode.org}, @code{#wget}. Come check it out!

@node Reporting Bugs, Portability, Internet Relay Chat, Various
@section Reporting Bugs
@cindex bugs
@cindex reporting bugs
@cindex bug reports

@c man begin BUGS
You are welcome to submit bug reports via the GNU Wget bug tracker (see
@url{https://savannah.gnu.org/bugs/?func=additem&group=wget}) or to our
mailing list @email{bug-wget@@gnu.org}.

Visit @url{https://lists.gnu.org/mailman/listinfo/bug-wget} to
get more info (how to subscribe, list archives, ...).

Before actually submitting a bug report, please try to follow a few
simple guidelines.

@enumerate
@item
Please try to ascertain that the behavior you see really is a bug.  If
Wget crashes, it's a bug.  If Wget does not behave as documented,
it's a bug.  If things work strange, but you are not sure about the way
they are supposed to work, it might well be a bug, but you might want to
double-check the documentation and the mailing lists (@pxref{Mailing
Lists}).

@item
Try to repeat the bug in as simple circumstances as possible.  E.g. if
Wget crashes while downloading @samp{wget -rl0 -kKE -t5 --no-proxy
http://example.com -o /tmp/log}, you should try to see if the crash is
repeatable, and if will occur with a simpler set of options.  You might
even try to start the download at the page where the crash occurred to
see if that page somehow triggered the crash.

Also, while I will probably be interested to know the contents of your
@file{.wgetrc} file, just dumping it into the debug message is probably
a bad idea.  Instead, you should first try to see if the bug repeats
with @file{.wgetrc} moved out of the way.  Only if it turns out that
@file{.wgetrc} settings affect the bug, mail me the relevant parts of
the file.

@item
Please start Wget with @samp{-d} option and send us the resulting
output (or relevant parts thereof).  If Wget was compiled without
debug support, recompile it---it is @emph{much} easier to trace bugs
with debug support on.

Note: please make sure to remove any potentially sensitive information
from the debug log before sending it to the bug address.  The
@code{-d} won't go out of its way to collect sensitive information,
but the log @emph{will} contain a fairly complete transcript of Wget's
communication with the server, which may include passwords and pieces
of downloaded data.  Since the bug address is publicly archived, you
may assume that all bug reports are visible to the public.

@item
If Wget has crashed, try to run it in a debugger, e.g. @code{gdb `which
wget` core} and type @code{where} to get the backtrace.  This may not
work if the system administrator has disabled core files, but it is
safe to try.
@end enumerate
@c man end

@node Portability, Signals, Reporting Bugs, Various
@section Portability
@cindex portability
@cindex operating systems

Like all GNU software, Wget works on the GNU system.  However, since it
uses GNU Autoconf for building and configuring, and mostly avoids using
``special'' features of any particular Unix, it should compile (and
work) on all common Unix flavors.

Various Wget versions have been compiled and tested under many kinds of
Unix systems, including GNU/Linux, Solaris, SunOS 4.x, Mac OS X, OSF
(aka Digital Unix or Tru64), Ultrix, *BSD, IRIX, AIX, and others.  Some
of those systems are no longer in widespread use and may not be able to
support recent versions of Wget.  If Wget fails to compile on your
system, we would like to know about it.

Thanks to kind contributors, this version of Wget compiles and works
on 32-bit Microsoft Windows platforms.  It has been compiled
successfully using MS Visual C++ 6.0, Watcom, Borland C, and GCC
compilers.  Naturally, it is crippled of some features available on
Unix, but it should work as a substitute for people stuck with
Windows.  Note that Windows-specific portions of Wget are not
guaranteed to be supported in the future, although this has been the
case in practice for many years now.  All questions and problems in
Windows usage should be reported to Wget mailing list at
@email{wget@@sunsite.dk} where the volunteers who maintain the
Windows-related features might look at them.

Support for building on MS-DOS via DJGPP has been contributed by Gisle
Vanem; a port to VMS is maintained by Steven Schweda, and is available
at @url{https://antinode.info/dec/sw/wget.html}.

@node Signals,  , Portability, Various
@section Signals
@cindex signal handling
@cindex hangup

Since the purpose of Wget is background work, it catches the hangup
signal (@code{SIGHUP}) and ignores it.  If the output was on standard
output, it will be redirected to a file named @file{wget-log}.
Otherwise, @code{SIGHUP} is ignored.  This is convenient when you wish
to redirect the output of Wget after having started it.

@example
$ wget http://www.gnus.org/dist/gnus.tar.gz &
...
$ kill -HUP %%
SIGHUP received, redirecting output to `wget-log'.
@end example

Other than that, Wget will not try to interfere with signals in any way.
@kbd{C-c}, @code{kill -TERM} and @code{kill -KILL} should kill it alike.

@node Appendices, Copying this manual, Various, Top
@chapter Appendices

This chapter contains some references I consider useful.

@menu
* Robot Exclusion::             Wget's support for RES.
* Security Considerations::     Security with Wget.
* Contributors::                People who helped.
@end menu

@node Robot Exclusion, Security Considerations, Appendices, Appendices
@section Robot Exclusion
@cindex robot exclusion
@cindex robots.txt
@cindex server maintenance

It is extremely easy to make Wget wander aimlessly around a web site,
sucking all the available data in progress.  @samp{wget -r @var{site}},
and you're set.  Great?  Not for the server admin.

As long as Wget is only retrieving static pages, and doing it at a
reasonable rate (see the @samp{--wait} option), there's not much of a
problem.  The trouble is that Wget can't tell the difference between the
smallest static page and the most demanding CGI.  A site I know has a
section handled by a CGI Perl script that converts Info files to @sc{html} on
the fly.  The script is slow, but works well enough for human users
viewing an occasional Info file.  However, when someone's recursive Wget
download stumbles upon the index page that links to all the Info files
through the script, the system is brought to its knees without providing
anything useful to the user (This task of converting Info files could be
done locally and access to Info documentation for all installed GNU
software on a system is available from the @code{info} command).

To avoid this kind of accident, as well as to preserve privacy for
documents that need to be protected from well-behaved robots, the
concept of @dfn{robot exclusion} was invented.  The idea is that
the server administrators and document authors can specify which
portions of the site they wish to protect from robots and those
they will permit access.

The most popular mechanism, and the @i{de facto} standard supported by
all the major robots, is the ``Robots Exclusion Standard'' (RES) written
by Martijn Koster et al. in 1994.  It specifies the format of a text
file containing directives that instruct the robots which URL paths to
avoid.  To be found by the robots, the specifications must be placed in
@file{/robots.txt} in the server root, which the robots are expected to
download and parse.

Although Wget is not a web robot in the strictest sense of the word, it
can download large parts of the site without the user's intervention to
download an individual page.  Because of that, Wget honors RES when
downloading recursively.  For instance, when you issue:

@example
wget -r http://www.example.com/
@end example

First the index of @samp{www.example.com} will be downloaded.  If Wget
finds that it wants to download more documents from that server, it will
request @samp{http://www.example.com/robots.txt} and, if found, use it
for further downloads.  @file{robots.txt} is loaded only once per each
server.

Until version 1.8, Wget supported the first version of the standard,
written by Martijn Koster in 1994 and available at
@url{http://www.robotstxt.org/orig.html}.  As of version 1.8,
Wget has supported the additional directives specified in the internet
draft @samp{<draft-koster-robots-00.txt>} titled ``A Method for Web
Robots Control''.  The draft, which has as far as I know never made to
an @sc{rfc}, is available at
@url{http://www.robotstxt.org/norobots-rfc.txt}.

This manual no longer includes the text of the Robot Exclusion Standard.

The second, less known mechanism, enables the author of an individual
document to specify whether they want the links from the file to be
followed by a robot.  This is achieved using the @code{META} tag, like
this:

@example
<meta name="robots" content="nofollow">
@end example

This is explained in some detail at
@url{http://www.robotstxt.org/meta.html}.  Wget supports this
method of robot exclusion in addition to the usual @file{/robots.txt}
exclusion.

If you know what you are doing and really really wish to turn off the
robot exclusion, set the @code{robots} variable to @samp{off} in your
@file{.wgetrc}.  You can achieve the same effect from the command line
using the @code{-e} switch, e.g. @samp{wget -e robots=off @var{url}...}.

@node Security Considerations, Contributors, Robot Exclusion, Appendices
@section Security Considerations
@cindex security

When using Wget, you must be aware that it sends unencrypted passwords
through the network, which may present a security problem.  Here are the
main issues, and some solutions.

@enumerate
@item
The passwords on the command line are visible using @code{ps}.  The best
way around it is to use @code{wget -i -} and feed the @sc{url}s to
Wget's standard input, each on a separate line, terminated by @kbd{C-d}.
Another workaround is to use @file{.netrc} to store passwords; however,
storing unencrypted passwords is also considered a security risk.

@item
Using the insecure @dfn{basic} authentication scheme, unencrypted
passwords are transmitted through the network routers and gateways.

@item
The @sc{ftp} passwords are also in no way encrypted.  There is no good
solution for this at the moment.

@item
Although the ``normal'' output of Wget tries to hide the passwords,
debugging logs show them, in all forms.  This problem is avoided by
being careful when you send debug logs (yes, even when you send them to
me).
@end enumerate

@node Contributors,  , Security Considerations, Appendices
@section Contributors
@cindex contributors

GNU Wget was written by Hrvoje Nikšić @email{hniksic@@xemacs.org},

However, the development of Wget could never have gone as far as it has, were
it not for the help of many people, either with bug reports, feature proposals,
patches, or letters saying ``Thanks!''.

Special thanks goes to the following people (no particular order):

@itemize @bullet
@item Dan Harkless---contributed a lot of code and documentation of
extremely high quality, as well as the @code{--page-requisites} and
related options.  He was the principal maintainer for some time and
released Wget 1.6.

@item Ian Abbott---contributed bug fixes, Windows-related fixes, and
provided a prototype implementation of the breadth-first recursive
download.  Co-maintained Wget during the 1.8 release cycle.

@item
The dotsrc.org crew, in particular Karsten Thygesen---donated system
resources such as the mailing list, web space, @sc{ftp} space, and
version control repositories, along with a lot of time to make these
actually work.  Christian Reiniger was of invaluable help with setting
up Subversion.

@item
Heiko Herold---provided high-quality Windows builds and contributed
bug and build reports for many years.

@item
Shawn McHorse---bug reports and patches.

@item
Kaveh R. Ghazi---on-the-fly @code{ansi2knr}-ization.  Lots of
portability fixes.

@item
Gordon Matzigkeit---@file{.netrc} support.

@item
Zlatko Čalušić, Tomislav Vujec and Dražen
Kačar---feature suggestions and ``philosophical'' discussions.

@item
Darko Budor---initial port to Windows.

@item
Antonio Rosella---help and suggestions, plus the initial Italian
translation.

@item
Tomislav Petrović, Mario Mikočević---many bug reports and
suggestions.

@item
Françis Pinard---many thorough bug reports and discussions.

@item
Karl Eichwalder---lots of help with internationalization, Makefile
layout and many other things.

@item
Junio Hamano---donated support for Opie and @sc{http} @code{Digest}
authentication.

@item
Mauro Tortonesi---improved IPv6 support, adding support for dual
family systems.  Refactored and enhanced FTP IPv6 code. Maintained GNU
Wget from 2004--2007.

@item
Christopher G.@: Lewis---maintenance of the Windows version of GNU WGet.

@item
Gisle Vanem---many helpful patches and improvements, especially for
Windows and MS-DOS support.

@item
Ralf Wildenhues---contributed patches to convert Wget to use Automake as
part of its build process, and various bugfixes.

@item
Steven Schubiger---Many helpful patches, bugfixes and improvements.
Notably, conversion of Wget to use the Gnulib quotes and quoteargs
modules, and the addition of password prompts at the console, via the
Gnulib getpasswd-gnu module.

@item
Ted Mielczarek---donated support for CSS.

@item
Saint Xavier---Support for IRIs (RFC 3987).

@item
Tim Rühsen---Loads of helpful patches, especially fuzzing support and
Continuous Integration. Maintainer since 2014.

@item
Darshit Shah---Many helpful patches. Community support on various platforms.
Maintainer since 2014.

@item
People who provided donations for development---including Brian Gough.
@end itemize

The following people have provided patches, bug/build reports, useful
suggestions, beta testing services, fan mail and all the other things
that make maintenance so much fun:

Tim Adam,
Adrian Aichner,
Martin Baehr,
Dieter Baron,
Roger Beeman,
Dan Berger,
T.@: Bharath,
Christian Biere,
Paul Bludov,
Daniel Bodea,
Mark Boyns,
John Burden,
Julien Buty,
Wanderlei Cavassin,
Gilles Cedoc,
Tim Charron,
Noel Cragg,
Kristijan Čonkaš,
John Daily,
Andreas Damm,
Ahmon Dancy,
Andrew Davison,
Bertrand Demiddelaer,
Alexander Dergachev,
Andrew Deryabin,
Ulrich Drepper,
Marc Duponcheel,
Damir Džeko,
Alan Eldridge,
Hans-Andreas Engel,
Aleksandar Erkalović,
Andy Eskilsson,
João Ferreira,
Christian Fraenkel,
David Fritz,
Mike Frysinger,
Charles C.@: Fu,
FUJISHIMA Satsuki,
Masashi Fujita,
Howard Gayle,
Marcel Gerrits,
Lemble Gregory,
Hans Grobler,
Alain Guibert,
Mathieu Guillaume,
Aaron Hawley,
Jochen Hein,
Karl Heuer,
Madhusudan Hosaagrahara,
HIROSE Masaaki,
Ulf Harnhammar,
Gregor Hoffleit,
Erik Magnus Hulthen,
Richard Huveneers,
Jonas Jensen,
Larry Jones,
Simon Josefsson,
Mario Jurić,
Hack Kampbjørn,
Const Kaplinsky,
Goran Kezunović,
Igor Khristophorov,
Robert Kleine,
KOJIMA Haime,
Fila Kolodny,
Alexander Kourakos,
Martin Kraemer,
Sami Krank,
Jay Krell,
Σίμος Ξενιτέλλης (Simos KSenitellis),
Christian Lackas,
Hrvoje Lacko,
Daniel S.@: Lewart,
Nicolás Lichtmeier,
Dave Love,
Alexander V.@: Lukyanov,
Thomas Lußnig,
Andre Majorel,
Aurelien Marchand,
Matthew J.@: Mellon,
Jordan Mendelson,
Ted Mielczarek,
Robert Millan,
Lin Zhe Min,
Jan Minar,
Tim Mooney,
Keith Moore,
Adam D.@: Moss,
Simon Munton,
Charlie Negyesi,
R.@: K.@: Owen,
Jim Paris,
Kenny Parnell,
Leonid Petrov,
Simone Piunno,
Andrew Pollock,
Steve Pothier,
Jan Přikryl,
Marin Purgar,
Csaba Ráduly,
Keith Refson,
Bill Richardson,
Tyler Riddle,
Tobias Ringstrom,
Jochen Roderburg,
Juan José Rodríguez,
Maciej W.@: Rozycki,
Edward J.@: Sabol,
Heinz Salzmann,
Robert Schmidt,
Nicolas Schodet,
Benno Schulenberg,
Andreas Schwab,
Steven M.@: Schweda,
Chris Seawood,
Pranab Shenoy,
Dennis Smit,
Toomas Soome,
Tage Stabell-Kulo,
Philip Stadermann,
Daniel Stenberg,
Sven Sternberger,
Markus Strasser,
John Summerfield,
Szakacsits Szabolcs,
Mike Thomas,
Philipp Thomas,
Mauro Tortonesi,
Dave Turner,
Gisle Vanem,
Rabin Vincent,
Russell Vincent,
Željko Vrba,
Charles G Waldman,
Douglas E.@: Wegscheid,
Ralf Wildenhues,
Joshua David Williams,
Benjamin Wolsey,
Saint Xavier,
YAMAZAKI Makoto,
Jasmin Zainul,
Bojan Ždrnja,
Kristijan Zimmer,
Xin Zou.

Apologies to all who I accidentally left out, and many thanks to all the
subscribers of the Wget mailing list.

@node Copying this manual, Concept Index, Appendices, Top
@appendix Copying this manual
  
@menu
* GNU Free Documentation License::  License for copying this manual.
@end menu

@node GNU Free Documentation License,  , Copying this manual, Copying this manual
@appendixsec GNU Free Documentation License
@cindex FDL, GNU Free Documentation License

@include fdl.texi


@node Concept Index,  , Copying this manual, Top
@unnumbered Concept Index
@printindex cp

@contents

@bye