Bash Builtin Commands

The set of portable commands.

Commands

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 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 (+).

Reserved Keywords

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

See here for break and continue.

See here for return.

See here for bg, coproc, fg, and jobs.

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

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