Builtin commands contained within the bash shell itself. How do I list all built-in bash commands on Linux / Apple OS X / *BSD / Unix like operating systems without reading large size bash man page?
A shell builtin is nothing but command or a function, called from a shell, that is executed directly in the shell itself. The bash shell executes the command directly, without invoking another program. You can view information for Bash built-ins with help command. There are different types of built-in commands.
### built-in command types
1. Bourne Shell Builtins: Builtin commands inherited from the Bourne Shell.
2. Bash Builtins: Table of builtins specific to Bash.
3. Modifying Shell Behavior: Builtins to modify shell attributes and optional behavior.
4. Special Builtins: Builtin commands classified specially by POSIX.
### How to see all bash builtins
Type the following command:
```
$ help
$ help | less
$ help | grep read
```
Sample outputs:
```
GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)
These shell commands are defined internally. Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.
A star (*) next to a name means that the command is disabled.
job_spec [&] history [-c] [-d offset] [n] or hist>
(( expression )) if COMMANDS; then COMMANDS; [ elif C>
. filename [arguments] jobs [-lnprs] [jobspec ...] or jobs >
for NAME [in WORDS ... ] ; do COMMAND> unset [-f] [-v] [name ...]
for (( exp1; exp2; exp3 )); do COMMAN> until COMMANDS; do COMMANDS; done
function name { COMMANDS ; } or name > variables - Names and meanings of so>
getopts optstring name [arg] wait [id]
hash [-lr] [-p pathname] [-dt] [name > while COMMANDS; do COMMANDS; done
help [-dms] [pattern ...] { COMMANDS ; }
```
### Viewing information for Bash built-ins
To get detailed info run:
```
help command
help read
```
To just get a list of all built-ins with a short description, execute:
`$ help -d`
### Find syntax and other options for builtins
Use the following syntax ' to find out more about the builtins commands:
```
help name
help cd
help fg
help for
help read
help :
```
Sample outputs:
```
:: :
Null command.
No effect; the command does nothing.
Exit Status:
Always succeeds
```
### Find out if a command is internal (builtin) or external
Use the type command or command command:
```
type -a command-name-here
type -a cd
type -a uname
type -a :
type -a ls
```
OR
```
type -a cd uname : ls uname
```
Sample outputs:
```
cd is a shell builtin
uname is /bin/uname
: is a shell builtin
ls is aliased to `ls --color=auto'
ls is /bin/ls
l is a function
l ()
{
ls --color=auto
}
```
OR
```
command -V ls
command -V cd
command -V foo
```
[![View list bash built-ins command info on Linux or Unix][1]][1]
### about the author
The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on [Twitter][2], [Facebook][3], [Google+][4].
