"improper AIX field descriptor" error on Debian 12 bookworm

[rudolfolah]

Error when running on Debian 12. I found this error while working on #1

CompletedProcess(args='-ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd', returncode=1, stdout='', stderr="error: improper AIX field descriptor\n\nUsage:\n ps [options]\n\n Try 'ps --help <simple|list|output|threads|misc|all>'\n  or 'ps --help <s|l|o|t|m|a>'\n for additional help text.\n\nFor more details see ps(1).\n")

This thread may offer some insight into the issue: https://groups.google.com/g/linux.debian.user/c/fmOBn7aQo9Q?pli=1

[rudolfolah]

Changing the entrypoint to bash and trying the command worked:

docker run -it --rm --entrypoint bash python:3.12-bookworm

root@55008b874ebd:/# ps
  PID TTY          TIME CMD
    1 pts/0    00:00:00 bash
    7 pts/0    00:00:00 ps

root@55008b874ebd:/# ps -ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd
                 STARTED USER                   PID  PPID     TIME %CPU %MEM   RSS    SZ S COMMAND         CMD
Sat Jul 13 02:28:35 2024 root                     1     0 00:00:00  0.0  0.0  3456  1118 S bash            bash
Sat Jul 13 02:29:01 2024 root                     8     1 00:00:00  0.0  0.0  3968  2146 R ps              ps -ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd

And here's what happens when we run it through Python:

docker run -it --rm python:3.12-bookworm
Python 3.12.4 (main, Jul  2 2024, 20:46:41) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> subprocess.run(args='-ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd', executable='ps')
  PID TTY          TIME CMD
    1 pts/0    00:00:00 python3
    7 pts/0    00:00:00 ps
CompletedProcess(args='-ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd', returncode=0)
>>> subprocess.run(args='-ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd', executable='ps', shell=True)
error: improper AIX field descriptor

Usage:
 ps [options]

 Try 'ps --help <simple|list|output|threads|misc|all>'
  or 'ps --help <s|l|o|t|m|a>'
 for additional help text.

For more details see ps(1).
CompletedProcess(args='-ewwo lstart,user:20,pid,ppid,time,%cpu,%mem,rss,sz,s,comm,cmd', returncode=1)

The shell=True may be causing the issue:

If shell is True, the specified command will be executed through the shell. This can be useful if you are using Python primarily for the enhanced control flow it offers over most system shells and still want convenient access to other shell features such as shell pipes, filename wildcards, environment variable expansion, and expansion of ~ to a user’s home directory. However, note that Python itself offers implementations of many shell-like features (in particular, glob, fnmatch, os.walk(), os.path.expandvars(), os.path.expanduser(), and shutil).

[rudolfolah]

Source code references for ps:

• procps - GNU GPL v2
• openbsd ps.c
• NetBSD ps.c
• htop DarwinProcess.c