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Explain that the commands affect 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.
42 lines
1.5 KiB
ReStructuredText
42 lines
1.5 KiB
ReStructuredText
unset
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-----
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Unset a variable, cache variable, or environment variable.
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Unset Normal Variable or Cache Entry
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: cmake
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unset(<variable> [CACHE | PARENT_SCOPE])
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Removes a normal variable from the current scope, causing it
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to become undefined. If ``CACHE`` is present, then a cache variable
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is removed instead of a normal variable. Note that when evaluating
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:ref:`Variable References` of the form ``${VAR}``, CMake first searches
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for a normal variable with that name. If no such normal variable exists,
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CMake will then search for a cache entry with that name. Because of this
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unsetting a normal variable can expose a cache variable that was previously
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hidden. To force a variable reference of the form ``${VAR}`` to return an
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empty string, use ``set(<variable> "")``, which clears the normal variable
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but leaves it defined.
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If ``PARENT_SCOPE`` is present then the variable is removed from the scope
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above the current scope. See the same option in the :command:`set` command
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for further details.
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Unset Environment Variable
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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.. code-block:: cmake
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unset(ENV{<variable>})
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Removes ``<variable>`` from the currently available
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:manual:`Environment Variables <cmake-env-variables(7)>`.
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Subsequent calls of ``$ENV{<variable>}`` will return the empty string.
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This command affects only the current CMake process, not the process
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from which CMake was called, nor the system environment at large,
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nor the environment of subsequent build or test processes.
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