zuberuber zuberuber - 22 days ago 6
Linux Question

Python subprocess command with pipe

I want to use

subprocess.check_output()
with
ps -A | grep 'process_name'
. I tried various solutions but so far nothing worked. Can someone guide me how to do it?

Answer

To use a pipe with the subprocess module, you have to pass shell=True.

However, this isn't really advisable for various reasons, not least of which is security. Instead, create the ps and grep processes separately, and pipe the output from one into the other, like so:

ps = subprocess.Popen(('ps', '-A'), stdout=subprocess.PIPE)
output = subprocess.check_output(('grep', 'process_name'), stdin=ps.stdout)
ps.wait()

In your particular case, however, the simple solution is to call subprocess.check_output(('ps', '-A')) and then str.find on the output.