CMake run custom command with mixed shell scripts

Question

Let's say we want to run following command in CMake add_custom_command :

echo "#define FOO \"$(sh tools/foo.sh)\"" > foo.h

The foo.sh is a script maintained by others so we could not easily change it here.

The problem is, CMake will not evaluate \\"$(sh tools/foo.sh)\\"' in add_costom_command`, instead it just copy them into foo.h directly, which is obvious not what we want.

In the generated build.make I found something like:

echo "#define FOO \"\$$(sh tools/foo.sh)\"" > .../foo.h

What're the escape rules for CMake add_custom_command COMMAND ?

How should I write the command in add_custom_command COMMAND ?

Answer 1

CMake syntax is crazy and it's not easy to make this kind of escaping (involves cmake , shell and makefile ) right. To work it around I suggest you put the shell command in a separate file (eg helper.sh ) in your project dir and then call it like this --

add_custom_command(
  ...
  COMMAND bash ${PROJECT_SOURCE_DIR}/helper.sh > foo.h
)