Help/variable/ENV.rst
Operator to read environment variables.
Use the syntax $ENV{VAR} to read environment variable VAR.
To test whether an environment variable is defined, use the signature
if(DEFINED ENV{<name>}) of the :command:if command.
.. note::
Environment variable names containing special characters like parentheses
may need to be escaped. (Policy :policy:CMP0053 must also be enabled.)
For example, to get the value of the Windows environment variable
ProgramFiles(x86), use:
.. code-block:: cmake
set(ProgramFiles_x86 "$ENV{ProgramFiles\(x86\)}")
For general information on environment variables, see the
:ref:Environment Variables <CMake Language Environment Variables>
section in the :manual:cmake-language(7) manual.