subprocess + python-daemon - bug/problem?

[Ben Finney]

Andy  Clegg <andy2.0 at gmail.com> writes:

> "import daemon
> import subprocess
> 
> daemon.DaemonContext(stderr = open("fakeConsole.txt","w+")).open()
> subprocess.Popen(['echo','1']).wait()"
> 
> However the error remains the same.

The error appears in the file specified for the stderr output of the
DaemonContext. Here it is without the unwanted extra line-wrapping that
seems to plague all Google Mail users (seriously, folks: get a real mail
provider that won't mangle your messages)::

    Traceback (most recent call last):
      File "/home/bignose/Projects/python/python-daemon/bin/andy-clegg-test", line 7, in <module>
        subprocess.Popen(['echo', '1']).wait()
      File "/usr/lib/python2.5/subprocess.py", line 1184, in wait
        pid, sts = self._waitpid_no_intr(self.pid, 0)
      File "/usr/lib/python2.5/subprocess.py", line 1014, in _waitpid_no_intr
        return os.waitpid(pid, options)
    OSError: [Errno 10] No child processes

I confirm that I'm getting the same error; Python 2.5.4.

My first thought was perhaps it's related to the fact that the process
has no stdout? But setting ‘stdout’ and ‘stderr’ to the same file::

    #! /usr/bin/python

    import daemon
    import subprocess

    fake_console = open("fake_console.txt", "w+")
    daemon.DaemonContext(stdout=fake_console, stderr=fake_console).open()
    subprocess.Popen(['echo', '1']).wait()

still gives the same error::

    1
    Traceback (most recent call last):
      File "/home/bignose/Projects/python/python-daemon/bin/andy-clegg-test", line 8, in <module>
        subprocess.Popen(['echo', '1']).wait()
      File "/usr/lib/python2.5/subprocess.py", line 1184, in wait
        pid, sts = self._waitpid_no_intr(self.pid, 0)
      File "/usr/lib/python2.5/subprocess.py", line 1014, in _waitpid_no_intr
        return os.waitpid(pid, options)
    OSError: [Errno 10] No child processes

I'm not familiar enough with the nuances of the ‘subprocess’ module to
know what might be going wrong here. I'd like to know whether it might
be a problem in the ‘python-daemon’ library.

-- 
 \     “Whatever a man prays for, he prays for a miracle. Every prayer |
  `\   reduces itself to this: “Great God, grant that twice two be not |
_o__)                                           four.”” —Ivan Turgenev |
Ben Finney