Unset built-in
The unset built-in unsets variables or functions.
Synopsis
unset [-f|-v] name…
Description
The built-in unsets variables or functions named by the operands.
Options
Either of the following options may be used to select what to unset:
- The
-v(--variables) option unsets variables. This is the default behavior. - The
-f(--functions) option unsets functions.
Operands
Operands are the names of variables or functions to unset.
Errors
Unsetting a read-only variable or function is an error.
It is not an error to unset a variable or function that is not set. The built-in ignores such operands.
Exit status
Zero if successful; non-zero if an error occurs.
Examples
See Removing variables and Removing functions.
Compatibility
The unset built-in is specified by POSIX.1-2024.
The behavior is not portable when both -f and -v are specified. Earlier versions of yash used to honor the last specified option, but this version errors out.
If neither -f nor -v is specified and the variable named by an operand is not set, POSIX allows the built-in to unset the same-named function if it exists. Yash does not do this.
POSIX requires that at least one operand be specified. Yash-rs currently does not detect this and allows the built-in to be called without any operands, but this may change in the future.
When a global variable is hidden by a local variable, the current implementation unsets the both. This is not portable. Old versions of yash used to unset the local variable only.