From 3df7b23d8f3d5916d78684ea621a2d5cf4d57ab2 Mon Sep 17 00:00:00 2001 From: struggling <630441839@qq.com> Date: Fri, 28 Aug 2015 23:33:13 +0800 Subject: [PATCH] Delete 20150827 Linux or UNIX--Bash Read a File Line By Line.md --- ... or UNIX--Bash Read a File Line By Line.md | 163 ------------------ 1 file changed, 163 deletions(-) delete mode 100644 sources/tech/20150827 Linux or UNIX--Bash Read a File Line By Line.md diff --git a/sources/tech/20150827 Linux or UNIX--Bash Read a File Line By Line.md b/sources/tech/20150827 Linux or UNIX--Bash Read a File Line By Line.md deleted file mode 100644 index c0a4b6c27c..0000000000 --- a/sources/tech/20150827 Linux or UNIX--Bash Read a File Line By Line.md +++ /dev/null @@ -1,163 +0,0 @@ -translation by strugglingyouth -Linux/UNIX: Bash Read a File Line By Line -================================================================================ -How do I read a file line by line under a Linux or UNIX-like system using KSH or BASH shell? - -You can use while..do..done bash loop to read file line by line on a Linux, OSX, *BSD, or Unix-like system. - -**Syntax to read file line by line on a Bash Unix & Linux shell:** - -1. The syntax is as follows for bash, ksh, zsh, and all other shells - -1. while read -r line; do COMMAND; done < input.file -1. The -r option passed to red command prevents backslash escapes from being interpreted. -1. Add IFS= option before read command to prevent leading/trailing whitespace from being trimmed - -1. while IFS= read -r line; do COMMAND_on $line; done < input.file - -Here is more human readable syntax for you: - - #!/bin/bash - input="/path/to/txt/file" - while IFS= read -r var - do - echo "$var" - done < "$input" - -**Examples** - -Here are some examples: - - #!/bin/ksh - file="/home/vivek/data.txt" - while IFS= read line - do - # display $line or do somthing with $line - echo "$line" - done <"$file" - -The same example using bash shell: - - #!/bin/bash - file="/home/vivek/data.txt" - while IFS= read -r line - do - # display $line or do somthing with $line - printf '%s\n' "$line" - done <"$file" - -You can also read field wise: - - #!/bin/bash - file="/etc/passwd" - while IFS=: read -r f1 f2 f3 f4 f5 f6 f7 - do - # display fields using f1, f2,..,f7 - printf 'Username: %s, Shell: %s, Home Dir: %s\n' "$f1" "$f7" "$f6" - done <"$file" - -Sample outputs: - -![Fig.01: Bash shell scripting- read file line by line demo outputs](http://s0.cyberciti.org/uploads/faq/2011/01/Bash-Scripting-Read-File-line-by-line-demo.jpg) - -Fig.01: Bash shell scripting- read file line by line demo outputs - -**Bash Scripting: Read text file line-by-line to create pdf files** - -My input file is as follows (faq.txt): - - 4|http://www.cyberciti.biz/faq/mysql-user-creation/|Mysql User Creation: Setting Up a New MySQL User Account - 4096|http://www.cyberciti.biz/faq/ksh-korn-shell/|What is UNIX / Linux Korn Shell? - 4101|http://www.cyberciti.biz/faq/what-is-posix-shell/|What Is POSIX Shell? - 17267|http://www.cyberciti.biz/faq/linux-check-battery-status/|Linux: Check Battery Status Command - 17245|http://www.cyberciti.biz/faq/restarting-ntp-service-on-linux/|Linux Restart NTPD Service Command - 17183|http://www.cyberciti.biz/faq/ubuntu-linux-determine-your-ip-address/|Ubuntu Linux: Determine Your IP Address - 17172|http://www.cyberciti.biz/faq/determine-ip-address-of-linux-server/|HowTo: Determine an IP Address My Linux Server - 16510|http://www.cyberciti.biz/faq/unix-linux-restart-php-service-command/|Linux / Unix: Restart PHP Service Command - 8292|http://www.cyberciti.biz/faq/mounting-harddisks-in-freebsd-with-mount-command/|FreeBSD: Mount Hard Drive / Disk Command - 8190|http://www.cyberciti.biz/faq/rebooting-solaris-unix-server/|Reboot a Solaris UNIX System - -My bash script: - - #!/bin/bash - # Usage: Create pdf files from input (wrapper script) - # Author: Vivek Gite under GPL v2.x+ - #--------------------------------------------------------- - - #Input file - _db="/tmp/wordpress/faq.txt" - - #Output location - o="/var/www/prviate/pdf/faq" - - _writer="~/bin/py/pdfwriter.py" - - # If file exists - if [[ -f "$_db" ]] - then - # read it - while IFS='|' read -r pdfid pdfurl pdftitle - do - local pdf="$o/$pdfid.pdf" - echo "Creating $pdf file ..." - #Genrate pdf file - $_writer --quiet --footer-spacing 2 \ - --footer-left "nixCraft is GIT UL++++ W+++ C++++ M+ e+++ d-" \ - --footer-right "Page [page] of [toPage]" --footer-line \ - --footer-font-size 7 --print-media-type "$pdfurl" "$pdf" - done <"$_db" - fi - -**Tip: Read from bash variable** - -Let us say you want a list of all installed php packages on a Debian or Ubuntu Linux, enter: - - # My input source is the contents of a variable called $list # - list=$(dpkg --list php\* | awk '/ii/{print $2}') - printf '%s\n' "$list" - -Sample outputs: - - php-pear - php5-cli - php5-common - php5-fpm - php5-gd - php5-json - php5-memcache - php5-mysql - php5-readline - php5-suhosin-extension - -You can now read from $list and install the package: - - #!/bin/bash - # BASH can iterate over $list variable using a "here string" # - while IFS= read -r pkg - do - printf 'Installing php package %s...\n' "$pkg" - /usr/bin/apt-get -qq install $pkg - done <<< "$list" - printf '*** Do not forget to run php5enmod and restart the server (httpd or php5-fpm) ***\n' - -Sample outputs: - - Installing php package php-pear... - Installing php package php5-cli... - Installing php package php5-common... - Installing php package php5-fpm... - Installing php package php5-gd... - Installing php package php5-json... - Installing php package php5-memcache... - Installing php package php5-mysql... - Installing php package php5-readline... - Installing php package php5-suhosin-extension... - *** Do not forget to run php5enmod and restart the server (httpd or php5-fpm) *** - --------------------------------------------------------------------------------- - -via: http://www.cyberciti.biz/faq/unix-howto-read-line-by-line-from-file/ - -作者：[作者名][a] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](https://linux.cn/) 荣誉推出