difference

#!/usr/bin/env python3
import subprocess
import sys

if len(sys.argv) < 3:
    print("Difference of 2 command outputs.")
    print("Example:")
    print("    difference \"ls -1 directory_a\" \"ls -1 directory_b\"")
    exit()

try:
    out0 = subprocess.check_output(sys.argv[1], shell=True).decode('utf-8').split('\n')
except subprocess.CalledProcessError:
    print("First command returned error, aborting")
    exit()
try:
    out1 = subprocess.check_output(sys.argv[2], shell=True).decode('utf-8').split('\n')
except subprocess.CalledProcessError:
    print("Second command returned error, aborting")
    exit()

out0 = filter(lambda x:x.strip() != '', out0)
out1 = filter(lambda x:x.strip() != '', out1)

set0 = set(out0)
set1 = set(out1)

setout = set0 - set1

print('\n'.join(sorted(list(setout))))