finally

#!/usr/bin/python

import argparse
import subprocess

# Parse command line arguments
parser = argparse.ArgumentParser(
    description='Execute a command until fails, then execute a different command')
parser.add_argument('until_command', help='Command to execute until failure')
parser.add_argument('finally_command', help='Command to execute upon failure')
args = parser.parse_args()

print "I'll run this until it fails: \n%s" % args.until_command
print "Once it fails (exit code != 0), I'll run: \n%s" % args.finally_command

working = False
times = 0
while working is not True:
    working = subprocess.call(args.until_command, shell=True) != 0
    times += 1
    print "I've run this command {0} times so far...".format(times)

subprocess.call(args.finally_command, shell=True)