Question

Basically I want to spawn a process changing its working directory.
My idea was to spawn a process and set the PWD enviroment variable.

There’s a way to obtain something like that?

(virtually I would like to change any of the environment variables for flexibility)

Answer 1

Just bind the default-directory variable before spawning your process. Example:

(let ((default-directory "/tmp/"))
  (call-process "/bin/bash" nil "*scratch*" nil "-c" "echo working dir is $PWD"))

I ran this from my *scratch* buffer and the string working dir is /tmp was added to the buffer.