Python: Catching the output from subprocess.call with stdout [duplicate]

Question

So im trying to save the output from my subprocess.call but I keep getting the following error: AttributeError: 'int' object has no attribute 'communicate'

Code is as follows:

p2 = subprocess.call(['./test.out', 'new_file.mfj', 'delete1.out'], stdout = PIPE)
output = p2.communicate[0]

The answers which recommend Popen were basically correct in 2012 when this question was asked, but the modern correct answer is to use subprocess.run, or subprocess.check_output if you need a simple API and/or compatibility back to older Python versions. The subprocess documentation spells this out, in the very first paragraph of the first section; "The recommended approach to invoking subprocesses is to use the run() function for all use cases it can handle." — tripleee
– tripleee, Commented Mar 4, 2022 at 12:32

Rob Wouters · Accepted Answer · 2012-01-03 14:49:53Z

5

You're looking for subprocess.Popen() instead of call().

You also need to change it to p2.communicate()[0].

answered Jan 3, 2012 at 14:49

Rob Wouters

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1 Comment

tripleee Over a year ago

This was correct in 2012, but the recommended solution now is to avoid Popen unless your use case requires it.

hughdbrown · Accepted Answer · 2012-01-03 14:53:51Z

4

That's because subprocess.call returns an int:

subprocess.call(args, *, stdin=None, stdout=None, stderr=None, shell=False)

    Run the command described by args. Wait for command to complete, then return the returncode attribute.

It looks like you want subprocess.Popen().

Here's a typical piece of code I have to do this:

p = Popen(cmd, stdout=PIPE, stderr=PIPE, bufsize=256*1024*1024)
output, errors = p.communicate()
if p.returncode:
    raise Exception(errors)
else:
    # Print stdout from cmd call
    print output

edited Jan 3, 2012 at 14:53

answered Jan 3, 2012 at 14:51

hughdbrown

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Comments

alemol · Accepted Answer · 2015-02-26 22:56:48Z

1

You should use subprocess

    try:            
        subprocess.check_output(['./test.out', 'new_file.mfj', 'delete1.out'], shell=True, stderr=subprocess.STDOUT)
    except subprocess.CalledProcessError as exception:
        print exception.output

answered Feb 26, 2015 at 22:56

alemol

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