Bash Builtin Commands

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.

Alias for source.

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:

Does nothing; arguments passed to it are expanded but immediately discarded.

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Alias

See here.

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Bg

See here.

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Bind

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Break

See here.

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Builtin

Execute a builtin command. This is only useful when reimplementing a builtin but still need to call the original builtin within the function.

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Caller

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Cd

Change the current working directory to a new path. Can be a relative or absolute path, as well as the special . and .. directories.

Note the rules for tilde expansion when using the ~ symbol here.

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

There is also special behavior around specifying nothing. cd is the same as cd ~.

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Command

Execute a command. This can be useful to call a command when there is a function with the same name. It can also be 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

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CompGen

See here.

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Complete

See here.

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CompOpt

See here.

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Continue

See here.

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Coproc

See here.

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Declare

Set a variable, optionally with a value.

declare a=1 b=2 c=3

When used within a function definition, the variable is set to 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 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 (+).

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Dirs

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Disown

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Echo

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Enable

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Eval

Executes a command. This is useful when building commands through parameter expansion.

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Exec

Replaces the shell with the specified command. This is useful in scripts that dispatch to other commands, like demenu(1).

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Exit

Causes a script or shell to exit immediately with a specified exit code.

If used in an interactive shell, or when used in a script that is sourced, causes the shell session to exit. That is likely not desireable; see return instead.

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Export

Marks one or more names as variables to be included in the environment of subsequently-called commands.

To set a variable and mark it simultaneously, try:

export varname="some value"

To instead export a function, use export -f funcname

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Fc

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Fg

See here.

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GetOpts

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Hash

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Help

Prints helpful information about a builtin command.

help help

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History

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Jobs

See here.

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Kill

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Let

See here.

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Local

Only valid within a function definition. See here.

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LogOut

Exit a login shell immediately.

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MapFile

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PopD

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PrintF

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PushD

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Pwd

Prints the current working directory.

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Read

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ReadArray

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ReadOnly

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Return

Only valid within a function definition. See here.

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Set

See here.

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Shift

Renames the special positional variables.

If shift is called with no argument, $2 is renamed to $1, $3 is renamed to $2, and so on.

shift N causes $N+1 to be renamed to $N, $N+2 to be renamed to $N+1, and so on.

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ShOpt

See here.

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Source

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Test

Aliased to [.

See here.

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Time

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Trap

See here.

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TypeSet

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UnAlias

See here.

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UnSet

See here.

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Wait

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