= Bash Builtin Commands =

The set of portable commands.

<<TableOfContents>>

----



== Commands ==

||'''Command'''  ||'''Description'''||'''Example'''||
||`.`            ||Alias for `source`|| ||
||`:`            ||No-op            || ||
||`alias`        ||Creates an [[Bash/Alias|alias]]|| ||
||`bind`         ||                 || ||
||`builtin`      ||Executes a builtin command|| ||
||`caller`       ||                 || ||
||`cd`           ||Changes the current working directory|| ||
||`command`      ||Executes a command|| ||
||`declare`      ||Set a variable, optionally with a value|| ||
||`dirs`         ||                 || ||
||`disown`       ||                 || ||
||`echo`         ||                 || ||
||`enable`       ||                 || ||
||`eval`         ||Executes a command|| ||
||`exec`         ||Replaces the shell with a command|| ||
||`exit`         ||Causes a script or shell to exit immediately|| ||
||`export`       ||Marks one or more names as variables to be included in the environment of subsequently-called commands||`export varname="some value"`||
||`fc`           ||                 || ||
||`getopts`      ||                 || ||
||`hash`         ||                 || ||
||`help`         ||Prints helpful information about a builtin command|| ||
||`history`      ||                 || ||
||`kill`         ||                 || ||
||`let`          ||                 || ||
||`local`        ||Only valid within a function definition; see [[Bash/Function#Local_Scope|here]]|| ||
||`logout`       ||Exits a login shell immediately|| ||
||`mapfile`      ||                 || ||
||`popd`         ||                 || ||
||`printf`       ||                 || ||
||`pushd`        ||                 || ||
||`pwd`          ||Prints the current working directory|| ||
||`read`         ||                 || ||
||`readarray`    ||                 || ||
||`readonly`     ||                 || ||
||`set`          ||Sets a [[Bash/ShellOptions|shell option]]|| ||
||`shift`        ||Renames the [[Bash/Variables#Positional_Variables|positional variables]]|| ||
||`shopt`        ||Sets a [[Bash/ShellOptions|shell option]]|| ||
||`source`       ||                 || ||
||`test`         ||Executes a [[Bash/Test|test]]|| ||
||`time`         ||                 || ||
||`trap`         ||Creates a trap   || ||
||`typeset`      ||                 || ||
||`unalias`      ||Removes an [[Bash/Alias|alias]]|| ||
||`unset`        ||Unsets a [[Bash/ShellOptions|shell option]]|| ||
||`wait`         ||                 || ||



=== Builtin ===

`builtin` can be useful to call a builtin command when there is a custom command with the same name.



=== Cd ===

Calling `cd` without an argument is the same as `cd ~`.

`cd -` changes the current working directory to the previous working directory.



=== Command ===

`command` can be useful to call a command when there is a function with the same name.

`command` is also commonly used to determine if a command is locally available.

{{{
if ! command -v mypy >/dev/null 2>&1; then
  echo "cannot locate mypy; is it installed?"
  exit
fi
}}}



=== Declare ===

When used within a function definition, the variable is set to [[Bash/Function#Local_Scope|local scope]].

To create a variable that is marked for export, use:

{{{
declare -x myvar
}}}

To create a variable that is marked for tracing, use:

{{{
declare -t myvar
}}}

To create a read-only constant, use:

{{{
declare -r myconst
}}}

To create an integer variable, use:

{{{
declare -i myinteger
}}}

To create an [[Bash/Array|array]], use:

{{{
declare -a myarray
}}}

To create an associative array, use:

{{{
declare -A myarray
}}}

With some exceptions, these options can be combined. Additionally, options can be explicitly disabled by substituting the dash (`-`) with a plus sign (`+`).

----



== Reserved Keywords ==

Some parts of the language are technically implemented as a command. 

See [[Bash/Looping|here]] for `break` and `continue`.

See [[Bash/Function#Error_and_Return_Codes|here]] for `return`.

See [[Bash/JobControl|here]] for `bg`, `coproc`, `fg`, and `jobs`.

Lastly, note that `compgen`, `complete`, and `compopt` all have to do with Bash completion.



----
CategoryRicottone