List of All Bash Inbuilt Variables – Linux 2018

Bash is the standard shell on most Linux distributions. However, there are other Linux shells available and there’s no requirement that Bash should be present on any particular distribution.

The Bash shell is open source software released under the GNU Pubic License (GPL). If you need to install Bash, the C language source code is freely available from the Free Software Foundation at http://www.gnu.org or through one of its download mirrors.

Also Read: Bash External Variables
Also Read: Bash Environment Variables

The Bash shell comes with various built-in help command to describe the various built-in Bash commands. The -s switch displays a summary for the command you specify.

alias	Define an alias for the specified command.
bg	Resume a job in background mode.
bind	Bind a keyboard sequence to a readline function or macro.
break	Exit from a for, while, select, or until loop.
builtin	Execute the specified shell built-in command.
cd	Change the current directory to the specified directory.
caller	Return the context of any active subroutine call.
command	Execute the specified command without the normal shell lookup.
compgen	Generate possible completion matches for the specified word.
complete	Display how the specified words would be completed.
continue	Resume the next iteration of a for, while, select, or until loop.
declare	Declare a variable or variable type.
dirs	Display a list of currently remembered directories.
disown	Remove the specified jobs from the jobs table for the process.
echo	Display the specified string to STDOUT.
enable	Enable or disable the specified built-in shell command.
eval	Concatenate the specified arguments into a single command, then execute the command.
exec	Replace the shell process with the specified command.
exit	Force the shell to exit with the specified exit status.
export	Set the specified variables to be available for child shell processes.
fc	Select a list of commands from the history list.
fg	Resume a job in foreground mode.
getopts	Parse the specified positional parameters.
hash	Find and remember the full pathname of the specified command.
help	Display a help file.
history	Display the command history.
jobs	List the active jobs.
kill	Send a system signal to the specified process ID (PID).
let	Evaluate each argument in a mathematical expression.
local	Create a limited-scope variable in a function.
logout	Exit a login shell.
popd	Remove entries from the directory stack.
printf	Display text using formatted strings.
pushd	Add a directory to the directory stack.
pwd	Display the pathname of the current working directory.
read	Read one line of data from STDIN and assign it to a variable.
readonly	Read one line of data from STDIN and assign it to a variable that can’t be changed.
return	Force a function to exit with a value that can be retrieved by the calling script.
set	Set and display environment variable values and shell attributes.
shift	Rotate positional parameters down one position.
shopt	Toggle the values of variables controlling optional shell behavior.
suspend	Suspend the execution of the shell until a SIGCONT signal is received.
test	Return an exit status of 0 or 1 based on the specified condition.
times	Display the accumulated user and system.
trap	Execute the specified command if the specified system signal is received.
type	Display how the specified word would be interpreted and used as a command.
ulimit	Set a limit on the specified resource for system users.
umask	Set default permissions for newly created files and directories.
unalias	Remove the specified alias.
unset	Remove the specified environment variable or shell attribute.
wait	Wait for the specified process to complete, and return the exit status.

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