POSIX return code processing example

script.py

#! /usr/bin/env python

import sys

def main():
  arg = sys.argv[1]
  if smth_went_wrong(arg):
    return 1  # failure code
  return 0  # POSIX success

sys.exit(main())

script.sh

# http://tldp.org/LDP/abs/html/comparison-ops.html
arg=`cat $1`

# case 1
python script.py "$arg"
retcode=$?
if [ $retcode -eq 1 ]; then
# "==" is a string comparison, not integer
    exit 0
fi

# case 2
python script.py "$arg" || exit 0