How to catch a bash error when the script is run through python

Question

I am trying to run a bash (or sh) script through a python script like so:

import os
cmd="/bin/echo {1..200000}"
out=os.system(cmd)

However, the command does not run and I get the following error:

/bin/echo: Argument list too long

I want to be able to capture this error specifically in my python script. try/except does not work here as it is not a python error, hence I want to know if there is any other way to capture this.

dont use os.system, use the subprocess module which has classes capable of reading stderr — JL Peyret
– JL Peyret, Commented Feb 20, 2020 at 21:28
Are you interested in "Argument list too long" specifically, or generally when the command does not execute successfully? — that other guy
– that other guy, Commented Feb 20, 2020 at 21:29
@thatotherguy I am specifically looking at "Argument list too long" error — Prachiti Prakash Prabhu
– Prachiti Prakash Prabhu, Commented Feb 20, 2020 at 21:31

Frank Merrow · Accepted Answer · 2020-02-20 21:28:54Z

4

The problem is that the error isn't happening in Python. The error happens in bash which is running as a separate process at that point. Take a look at the Python module "subprocess". It is more complex to set up than os.system(), but it allows you to capture stdin and stdout and process them after the process has terminated.

answered Feb 20, 2020 at 21:28

Frank Merrow

1,0091 gold badge9 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

that other guy Over a year ago

The extra benefit of this is that you can skip bash/sh entirely, invoke the same command yourself (subprocess.run(["/bin/echo"] + list(map(str, range(1, 200001))))), and then it'll raise an OSError that can not only be caught, but can be differentiated from all other execution failures with its errno property

Collectives™ on Stack Overflow

How to catch a bash error when the script is run through python

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related