What's the CMake syntax to set and use variables?

Question

I\'m asking this as a reminder to myself the next time I use CMake. It never sticks, and Google results aren\'t great.

What\'s the syntax to set and use variables in

Answer 1

$ENV{FOO} for usage, where FOO is being picked up from the environment variable. otherwise use as ${FOO}, where FOO is some other variable. For setting, SET(FOO "foo") would be used in CMake.