Re: Python script + v4lctl

[Gabriel Genellina]

En Mon, 20 Oct 2008 06:15:34 -0200, Gatis <ga****@inbox.lvescribió:

I wrote script that in case of some event takes picture using usb
webcam [Creative Live! Cam Vista IM (VF0420)] and command line utility
v4lctl (from package xawtv).
Problem1:
To catch error and info messages from script I used:
sys.stdout = open('/tmp/log','a')
sys.stderr=sys.stdout
All writes to log file well, except v4lctl error messages. If script
is run from commandline, than v4lctl error messages are shown there.
How to catch these messages?

Use the subprocess module to invoke the external program; see
http://docs.python.org/library/subprocess.html specially the examples at
the end.

Problem2:
When script is run from /etc/init.d (in runlevel 2) during boot, no
pictures are taken. I can't tell error message, because of Problem1.
If I execute now v4lctl from commandline (while my script is running
in background), picture is taken.

Once you start using subprocess, you could write to some file what you get
from the communicate() method - the error messages, if any, should be
there.

--
Gabriel Genellina