pythongh-120743: Soft deprecate os.popen() function (python#120744)

Soft deprecate os.popen() and os.spawn*() functions.

Author: vstinner

Doc/library/os.rst

@@ -4642,6 +4642,10 @@ written in Python, such as a mail server's external command delivery program.
       Use :class:`subprocess.Popen` or :func:`subprocess.run` to
       control options like encodings.
 
+   .. deprecated:: 3.14
+      The function is :term:`soft deprecated` and should no longer be used to
+      write new code. The :mod:`subprocess` module is recommended instead.
+
 
 .. function:: posix_spawn(path, argv, env, *, file_actions=None, \
                           setpgroup=None, resetids=False, setsid=False, setsigmask=(), \
@@ -4868,6 +4872,10 @@ written in Python, such as a mail server's external command delivery program.
    .. versionchanged:: 3.6
       Accepts a :term:`path-like object`.
 
+   .. deprecated:: 3.14
+      These functions are :term:`soft deprecated` and should no longer be used
+      to write new code. The :mod:`subprocess` module is recommended instead.
+
 
 .. data:: P_NOWAIT
           P_NOWAITO
@@ -4972,7 +4980,7 @@ written in Python, such as a mail server's external command delivery program.
    shell documentation.
 
    The :mod:`subprocess` module provides more powerful facilities for spawning
-   new processes and retrieving their results; using that module is preferable
+   new processes and retrieving their results; using that module is recommended
    to using this function.  See the :ref:`subprocess-replacements` section in
    the :mod:`subprocess` documentation for some helpful recipes.
 

Doc/whatsnew/3.14.rst

@@ -144,6 +144,11 @@ Deprecated
   as a single positional argument.
   (Contributed by Serhiy Storchaka in :gh:`109218`.)
 
+* :term:`Soft deprecate <soft deprecated>` :func:`os.popen` and
+  :func:`os.spawn* <os.spawnl>` functions. They should no longer be used to
+  write new code.  The :mod:`subprocess` module is recommended instead.
+  (Contributed by Victor Stinner in :gh:`120743`.)
+
 
 Removed
 =======

Misc/NEWS.d/next/Library/2024-06-19-15-43-04.gh-issue-120743.CMMl2P.rst

@@ -0,0 +1,3 @@
+:term:`Soft deprecate <soft deprecated>` :func:`os.popen` and :func:`os.spawn*
+<os.spawnl>` functions. They should no longer be used to write new code. The
+:mod:`subprocess` module is recommended instead. Patch by Victor Stinner.