readonly.md

The readonly builtin command

Synopsis

readonly [-p] [-a] [-A] [-f] [NAME[=VALUE] ...]

Description

The readonly builtin command is used to mark variables or functions as read-only, which means unchangeable. This implies that it can't be unset anymore. A readonly variable may not be redefined in child scopes. A readonly global may not be redefined as a function local variable. Simple command environment assignments may not reference readonly variables.

Options

Option	Description
-a	refer to normal arrays
-A	refer to associative arrays
-f	refer to functions
-p	print all read-only variables or functions, -a, -A and -f can be used to filter. The output is reusable as input

An argument of -- disables further option processing.

Return status

Status	Reason
0	no error
!=0	invalid option
!=0	invalid combination of options
!=0	a given NAME is invalid

Examples

Portability considerations

• in POSIX(r), only the -p option is specified

See also

• declare
• unset