random python periodic backup

periodic_packup.py

#!/usr/bin/python

# Copyright 2011 (C) Daniel Richman
#
# This programme is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This programme is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this programme.  If not, see <http://www.gnu.org/licenses/>.

import sys
import os
import time
import shutil
import traceback

usage = "Usage: {0} <source> <backup directory> <period in minutes>"

def main():
    if len(sys.argv) != 4:
        print usage.format(sys.argv[0])
        return False

    source = os.path.abspath(sys.argv[1])
    backup_dir = os.path.abspath(sys.argv[2])

    if not os.path.isdir(source):
        print "Bad source path"
        return False

    if not os.path.isdir(backup_dir):
        print "Bad backup_dir"
        return False

    try:
        period = int(sys.argv[3])
        assert period > 0
    except:
        print "Bad period value"
        return False

    print "Backing up from: {0}".format(source)
    print "Backing up to: {0}".format(backup_dir)
    print "Every {0} minutes.".format(period)

    try:
        while True:
            caught_backup(source, backup_dir)
            time.sleep(period )#* 60)
    except KeyboardInterrupt:
        print "Caught Ctrl-C; exiting."
        return True

def caught_backup(source, backup_dir):
    try:
        backup(source, backup_dir)
    except:
        print "Something went wrong: "
        traceback.print_exc()
        print "Backup failed"
    print ""

def backup(source, backup_dir):
    print "Backup time!"
    dest = os.path.join(backup_dir, backup_name(source))
    print "Copying '{0}' to '{1}'".format(source, dest)
    shutil.copytree(source, dest)
    print "Backup done"

def backup_name(source):
    return time.strftime("%Y%m%d_%H%M%S", time.gmtime())

if __name__ == "__main__":
    try:
        retval = main()
    except:
        print "The program crashed. This is bad."
        sys.exit(1)
    sys.exit(retval)