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Hi,

Trying to learn how to run a linux command and get the stdout and
stderr. I'm trying the following:

>>> cmd3 = r'ffmpeg -i /home/giga/Desktop/Guitar1.flv'
>>> p = Popen(cmd3, stdout=PIPE, stderr=PIPE)

Traceback (most recent call last):
File "<pyshell#73>", line 1, in <module>
p = Popen(cmd3, stdout=PIPE, stderr=PIPE)
File "/usr/lib/python2.6/subprocess.py", line 623, in __init__
errread, errwrite)
File "/usr/lib/python2.6/subprocess.py", line 1141, in
_execute_child
raise child_exception
OSError: [Errno 2] No such file or directory

But:

>>> if os.path.exists(r'/home/giga/Desktop/Guitar1.flv'):
print "exist"

exist
>>>

And just running ffmpeg alone seems as expected:

>>> cmd2=r'ffmpeg'
>>> p = Popen(cmd2, stdout=PIPE, stderr=PIPE)
>>> stdout, stderr = p.communicate()
>>> stdout
'Hyper fast Audio and Video encoder\nusage: ffmpeg [options] [[infile
options] -i infile]... {[outfile options] outfile}...\n\n'
>>> stderr
"FFmpeg version git-N-29152-g0ba8485, Copyright (c) 2000-2011 the
FFmpeg developers\n built on Apr 16 2011 16:40:56 with gcc 4.4.5\n
configuration: --enable-gpl ...snip...

Also if I run the exact command (cmd3) in the terminal it works OK.
Why is it not finding the file? Thanks, help appreciated.

On Mon, Apr 18, 2011 at 4:07 PM, goldtech <> wrote:
> Hi,
>
> Trying to learn how to run a linux command and get the stdout and
> stderr. I'm trying the following:
>
>>>> cmd3 = r'ffmpeg -i /home/giga/Desktop/Guitar1.flv'
>>>> p = Popen(cmd3, stdout=PIPE, stderr=PIPE)
>
> Traceback (most recent call last):
> Â*File "<pyshell#73>", line 1, in <module>
> Â* Â*p = Popen(cmd3, stdout=PIPE, stderr=PIPE)
> Â*File "/usr/lib/python2.6/subprocess.py", line 623, in __init__
> Â* Â*errread, errwrite)
> Â*File "/usr/lib/python2.6/subprocess.py", line 1141, in
> _execute_child
> Â* Â*raise child_exception
> OSError: [Errno 2] No such file or directory
>
> But:
>
>>>> if os.path.exists(r'/home/giga/Desktop/Guitar1.flv'):
> Â* Â* Â* Â*print "exist"
<snip>
> Also if I run the exact command (cmd3) in the terminal it works OK.
> Why is it not finding the file? Thanks, help appreciated.

Read The Fine Manual:
http://docs.python.org/library/subpr...bprocess.Popen :
"On Unix, with shell=False (default): [...] If a string is specified
for args, it will be used as the name or path of the program to
execute; ***this will only work if the program is being given no
arguments.***" (emphasis added)

The system is interpreting the entire command string as the path to an
executable; obviously there's no directory named "ffmpeg -i ", so the
path is invalid, hence the error.

Try instead:
cmd3 = ['ffmpeg', '-i', '/home/giga/Desktop/Guitar1.flv']

Cheers,
Chris
--
http://blog.rebertia.com

> Read The Fine Manual:http://docs.python.org/library/subpr...process.Popen:

snip...
>
> Try instead:
> cmd3 = ['ffmpeg', '-i', '/home/giga/Desktop/Guitar1.flv']
>
> Cheers,
> Chris
> --http://blog.rebertia.com

No doubt, I should RTFM...you're right!

Yes, works like a charm now.

Thanks so much for the help. I really appreciate it!