unset - Unset values and attributes of variables and functions

Format

unset name ...

unset -fv name ...

tcsh shell: unset pattern

Description

Calling unset with no options removes the value and attributes of each variable or function name.

In the tcsh shell, unset removes all variables whose names match pattern, unless they are read-only. For example: 
unset *
which we strongly recommend you do not do, will remove all variables unless they are read-only. It is not an error for nothing to be unset. For more information, see tcsh - Invoke a C shell.

Options

-f
Removes the value and attributes of each function name.
-v
Removes the attribute and value of the variable name. This option is the default if no options are specified.

unset cannot remove names that have been set read-only.

Usage notes

unset is a special built-in shell command.

Localization

unset uses the following localization environment variables:
  • LANG
  • LC_ALL
  • LC_MESSAGES
  • NLSPATH

Exit values

0
Successful completion.
1
Failure due to an incorrect command-line option.
2
Failure due to an incorrect command-line argument.

Otherwise, unset returns the number of specified names that are incorrect, not currently set, or read-only.

Messages

Possible error messages include:
name readonly variable
The given name cannot be deleted because it has been marked read-only.

Portability

POSIX.2, X/Open Portability Guide.

Related information

readonly, sh, tcsh