The given names are marked readonly; the values of these names may not be changed by subsequent assignment.
readonly [-apf] [name[=word] ...]
- -f set also the functions corresponding to the names read-only
- -a restricts the variables to arrays.
- -p prints a list of all readonly names. The -p option causes output to be displayed in a format that may be reused as input.
- [name[=word] …] The value of the variable is set to word.
Without options, a list of all readonly names is printed.
The return status is 0 unless:
- an invalid option is encountered,
- one of the names is not a valid shell variable name,
- or -f is supplied with a name that is not a function.