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