Redirect stdout & stderr (similar to a daemon)

[Mel Wilson]

In article <40b9cd69 at news.starhub.net.sg>,
Tsai Li Ming <mailinglist at ltsai.com> wrote:
>I have a problem with a redirecting stdout and stderr. I am a top level
>module and has no control over the imported modules that are making
>system calls such as os.system or popen2.* . I have tried the simplest
>method of capturing stdout, stderr via:
>
>saveout = sys.stdout
>sys.stdout = file_obj
>
>print 1 # works
>os.system('w') # Doesn't work

   I think the problem here is that os.system runs a
shell with its own new set of process parameters,
including its own stdin, stdout, etc.

   I would try one of the os.exec's or os.spawn's here
instead.

>[ ... ]
># Redirect standard file descriptors.
>os.dup2(si.fileno(), sys.stdin.fileno())
>os.dup2(so.fileno(), sys.stdout.fileno())
>os.dup2(se.fileno(), sys.stderr.fileno())

   These modify the actual file objects represented by
'sys.stdin', etc.  There's no coming back from that.

        Regards.        Mel.