Help/command/unset.rst
Unset a variable, cache variable, or environment variable.
Unset Normal Variable ^^^^^^^^^^^^^^^^^^^^^
.. signature:: unset(<variable> [PARENT_SCOPE]) :target: normal
Removes a normal variable from the current scope, causing it to become undefined.
If PARENT_SCOPE is present then the variable is removed from the scope
above the current scope. See the same option in the :command:set command
for further details.
.. include:: include/UNSET_NOTE.rst
Unset Cache Entry ^^^^^^^^^^^^^^^^^
.. signature:: unset(CACHE{<variable>}) :target: CACHE
.. versionadded:: 4.2
Removes <variable> from the cache, causing it to become undefined.
.. signature:: unset(<variable> CACHE) :target: CACHE_legacy
This signature is supported for compatibility purpose. Use preferably the other one.
Unset Environment Variable ^^^^^^^^^^^^^^^^^^^^^^^^^^
.. signature:: unset(ENV{<variable>}) :target: ENV
Removes <variable> from the currently available
:manual:Environment Variables <cmake-env-variables(7)>.
Subsequent calls of $ENV{<variable>} will return the empty string.
This command affects only the current CMake process, not the process from which CMake was called, nor the system environment at large, nor the environment of subsequent build or test processes.
See Also ^^^^^^^^
set