execute_process only run once

In CMakeLists.txt, execute_process only run once while run the CMakeLists.txt at first time?
If config is done and run the CMakeLists.txt, the execute_process command will not be run?

Unless you somehow guard against it, it’ll run each time a re-configure is triggered.

If no re-configure,it will be run?
I just want to do a job during configure process every time.

It runs each time CMake processes the CMakeLists.txt, so each time you (or your IDE) issue a cmake command or if the generated rules trigger a re-configure. It does not run by itself.

But in my ENV(windows+MSYS2),the command will not be run after config.

the command is like the below
execute_process(COMMAND perl.exe a.pl a.h INPUT_FILE a.txt)
it run the window command perl.exe a.pl a.h < a.txt.

And what does “issue a cmake command” mean?How to do this?

It’s when you actually run cmake. Like for the initial configuration.

At best show us an actual minimal example of what you’re doing, what you expect to happen, and what happens instead.