Script to check free disk space, and disk space consumption and print an atert. Quick instructions: place it in /root/scripts and configure a daily or weekly cron.

diskfree.py

#!/usr/bin/python
# -*- coding: UTF-8 -*-

# set the minimum disk space available to alert on (in GB).
minimum = 5 
# disk space variation (in GB) threshhold. 'delta GB have been consumed between the last two checks'.
delta = 1

import commands
import pickle

try:
    f = open('/root/scripts/diskfree.dat', 'r')
    before = pickle.load(f)
    f.close()
except IOError: # ie. file not found
    before = None

r = commands.getstatusoutput('df')
if r[0] == 0:
    lines = r[1].split('\n')
    del lines[0]
    for line in lines:
        fs, size, used, available, percent, mp = line.split()
        if mp != '/': continue
	available = int(available)
        # store the available amount for tomorrow
        f = open('/root/scripts/diskfree.dat', 'w')
        pickle.dump(available, f)
        f.close()
        if available < (1048576 * minimum):
            print "Less tham %sGB of free space left!" % minimum
	if before is not None:
            variation = available - before
            if variation > (1048576 * delta):
                vgb = variation / 1048576.0
                print "In the period between the last two checks, disk usage has grown in %sGB" %vgb