See the discussion for the rationale: Is time to remove os module spawn* functions?

See also the discussion: How to deal with unsafe/broken os.spawn* arg handling behavior on Windows (Nov 2022).

Advantages of the subprocess module:

• subprocess restores the signal handlers (reliable behavior).
• subprocess closes all file descriptors (more secure).
• subprocess doesn't use a shell by default, shell=True must be used explicitly.
• subprocess is the defacto standard way to spawn processes in Python.

Examples of os functions issues:

• os.popen() and os.system() always use shell=True, it cannot be disabled. (higher risk of shell code injection)
• os.popen().close() return value depends on the platform. (not portable)
• os.popen().close() return value is a "wait status", not an exit code: waitstatus_to_exitcode() must be used to get a return code.
• There are 8 os.spawn*() functions, it's more error prone and harder to use than subprocess APIs.
• os.spawn*() functions return an exit code 1 if the program is not found instead of raising an exception. It's harder to distinguish if the program exists and has an exit code of 1, or if it doesn't exist.
• The os.spawn*() functions are not safe for use in multithreaded programs on POSIX systems as they use fork()+exec() from Python there.

Linked PRs

• gh-120743: Soft deprecate os.popen() function #120744