Brian <[EMAIL PROTECTED]> writes:
> On a Slackware 9.1 box, I'm trying to detect if mpg123 is currently
> running/playing a song so that when the song is done, it'll play the next
> in the list. The problem is that popen'ing ps doesn't always give a
> correct return. My function is below and I added a second check that runs
> 1 second later which sometimes works, sometimes doesn't.
>
> Here's my function:
>
> def pid_defunct():
> #1 = defunct processes
> #2 = show is currently playing
> #0 = no mpg123 processes found
> t = os.popen( "ps axc | grep '[mpg123] <defunct>'" ).read()
> if len(t) > 0:
> return 1
> else:
> t = os.popen( "ps axc | grep 'mpg123'" ).read()
> if len(t) > 0:
> return 2
> else:
> print "Check 1: mpg123 is dead"
> #Check twice, because popen doesn't always return
> #correct value
> time.sleep(1)
> t = os.popen( "ps axc | grep 'mpg123'" ).read()
> if len(t) > 0:
> print "Check 1 was wrong"
> return 2
> else:
> print "Check 2: mpg123 is dead"
> return 0
>
>
> This function is run during each iteration of a loop with a time.sleep(1)
> executed right before it. Is there a better way to make this work?
Yeah, but it takes work on both ends. You could wrap your mpg123 in a
shell script like so:
#!/bin/sh
mpg123 "$@" &
echo $! >/tmp/mpg123.pid
Or in python 2.4:
#!/usr/bin/env python
from subprocess import Popen
p = Popen('mpg123')
pidfile = file('/tmp/mpg123.pid', 'w')
pidfile.write("%d" % p.pid)
pidfile.close()
Then have your check program do (again, using the 2.4 subprocess module)
from subprocess import Popen, PIPE
try:
pidfile = file('/tmp/mpg123.pid')
except IOError:
print 'mpg123 is dead'
else:
pid = pidfile.read()
t = Popen('ps p %s' % pid, shell=True, stdout=PIPE).stdout
if t.readlines() < 2:
print 'mpg123 is dead'
os.remove('/tmp/mpg123.pid')
return 0
return 2
Basically, instead of trusting grep to find mpg123, save the pid in a
file and let ps find it (or not) by pid.
<mike
--
Mike Meyer <[EMAIL PROTECTED]> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.
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