Subprocess and list comprehension in python

Question

Im trying to execute the tasklist command using subprocess.check_output. Then taking that output (each PID) and adding it to a list.

The problem im having is that my list comprehension seems to be making the list for each digit in the PID rather than the entire PID.

Ive played around with it for a while now trying out various comprehensions ive found using google but cant get it working as id like. Im sure there's something stupid I'm doing wrong but as they "Its simple if you know how".

Any help would be appreciated

EXAMPLE OUTPUT

['1', '2', '4', '7', '2', '\n', '1', '3', '0', '2', '8', '\n']

CODE

>>> import subprocess
>>> cmd = 'cmd.exe /C tasklist| find "mstsc"| cut -d" " -f21'
>>> out = subprocess.check_output(cmd)
>>> tasklist = [task for task in out if task != None]
>>> print tasklist
['1', '2', '4', '7', '2', '\n', '1', '3', '0', '2', '8', '\n']
>>>

`split` `out` along newlines?, so instead of `out = subprocess.check_output(cmd)`, use `out=subprocess.check_output(cmd).split('\n')` or something similar — cactus1, Mar 11 '14 at 18:15
`check_output()` appears to be giving you a string, not a list? @cactus1 probably has the right idea. — Michelle, Mar 11 '14 at 18:18
@cactus1 rofl see simple ^_^ thanks. Will keep that in mind next time. Worked a treat — iNoob, Mar 11 '14 at 18:29
@cactus1 want to give an answer so I can give you the relevant kudos — iNoob, Mar 11 '14 at 18:30
Eh, I guess it'd be good for anyone else having a similar problem — cactus1, Mar 11 '14 at 22:15

score 0 · Answer 1 · answered Mar 11 '14 at 22:18

Looks like subprocess.check_output(cmd) returns a string rather than a list of strings, so you need to split() it to get the list you want to process using the comprehension:

import subprocess

cmd = 'cmd.exe /C tasklist| find "mstsc"| cut -d" " -f21'
out = subprocess.check_output(cmd).split('\n')
tasklist = [task for task in out if task != None]
print tasklist

Subprocess and list comprehension in python

1 Answers1

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