# ENV

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 `if()` command.

Note

Environment variable names containing special characters like parentheses may need to be escaped. (Policy `CMP0053` must also be enabled.) For example, to get the value of the Windows environment variable `ProgramFiles(x86)`, use:

    set(ProgramFiles_x86 "$ENV{ProgramFiles\(x86\)}")

For general information on environment variables, see the Environment Variables section in the `cmake-language(7)` manual.