simple script for rsync backup (server pull)

#!/usr/bin/env python

import datetime
import glob
import os
import shutil
import subprocess
import sys
import time

source = sys.argv[1]
if not ':' in source:
    source = os.path.abspath(source)
repository = os.path.abspath(sys.argv[2])
# assume the pruning script is in the same folder as this script
prune = os.path.join(os.path.dirname(sys.argv[0]), 'prune.py')

target = os.path.join(repository, 'pending')
exclude = os.path.join(repository, 'rsync.exclude')
rsynclogname = 'rsync.log'
rsynclog = os.path.join(repository, rsynclogname)
prunelog = os.path.join(repository, 'prune.log')

while True:
    command = 'rsync'
    options = [
        '--archive',
        '--delete',
# uncomment the next line if the backup server doesn't have user names matching the clients'
#        '--numeric-ids',
        '--exclude-from=' + exclude,
        '--log-file=' + rsynclog
        ]

    # find the most recent successful backup, if any, so we can hard-link the new backup to it
    folders = glob.glob(os.path.join(repository, '20*'))
    if folders:
        folders.sort()
        options.append('--link-dest=' + folders.pop())

    args = [command] + options + [source] + [target]

    result = subprocess.call(args)
    next = time.time() + 3600

    # return code 24 means some files disappeared before they could be copied, which we consider benign
    if result == 0 or result == 24:
        mtime = datetime.datetime.fromtimestamp(os.path.getmtime(rsynclog))
        snapshotname = mtime.strftime('%Y%m%d-%H%M%S')
        snapshotpath = os.path.join(repository, snapshotname)
        os.rename(target, snapshotpath)
        shutil.move(rsynclog, snapshotpath)

        subprocess.call([prune, repository])
        if os.path.exists(prunelog):
            shutil.move(prunelog, snapshotpath)

    # wait at least 1 hour between backups
    pause = next - time.time()
    if pause > 0:
        time.sleep(pause)