Watching for file changes on a shared linux web server

$NEWPROJECT has a script which runs daily to produce a file which will be available for download, but aside from that one expected daily task, there shouldn’t be any unexpected changes to the content on the website.

As I’m hosting this on a shared webhost, I can’t install Tripwire or anything like that, and to be honest, for what I’m using it for, I probably don’t need it. So, instead, I wrote my own really simple file change monitor which runs as a CronJob.

Here’s the code:

#! /bin/bash
# This file is called
function sha512sum_files() {
find $HOME/$DIR/* -type f -exec sha512sum '{}' \; >> $SCAN_ROOT/current_status
mv $SCAN_ROOT/current_status $SCAN_ROOT/old_status
for DIR in site_root media/[A-Za-z]*
diff -U 0 $SCAN_ROOT/old_status $SCAN_ROOT/current_status

And here’s my crontab:

# Minute Hour Day of Month Month Day of Week Command
# (0-59) (0-23) (1-31) (1-12 or Jan-Dec) (0-6 or Sun-Sat)
0,15,30,45 * * * * /home/siteuser/scan/

And lastly, a sample of the output

--- /home/siteuser/scan/old_status 2010-10-25 14:30:03.000000000 -0700
+++ /home/siteuser/scan/current_status 2010-10-25 14:45:06.000000000 -0700
@@ -4 +4 @@
-baeb2692403619398b44a510e8ca0d49db717d1ff7e08bf1e210c260e04630606e9be2a3aa80f7db3d451e754e189d4578ec7b87db65e6729697c735713ee5ed /home/siteuser/site_root/LIBRARIES/library.php
+c4d739b3e0a778009e0d53315085d75cf8380ac431667c31b23e4b24d4db273dfc98ffad6842a1e5f59d6ea84c33ecc73bed1437e6105475fefd3f3a966de118 /home/siteuser/site_root/LIBRARIES/library.php
@@ -71 +71 @@
-88ddd746d70073183c291fa7da747d7318caa697ace37911db55afce707cd1634f213f340bb4870f1194c48292f846adaf006ad61b4ff1cb245972c26962b42d /home/siteuser/site_root/api.php
+d79e8a6e6c3db39e07c22e7b7485050007fd265ad7e9bdda728866f65638a8aa534f8cb51121a68e9287f384e8694a968b48d840d37bcd805c117ff871e7c618 /home/siteuser/site_root/api.php

While this isn’t the most technically sound way (I’m sure) of checking for file changes, at least it gives me some idea (to within 15 minutes or so) of what files have been changed, so gives me a time to start hunting.


He/Him. Husband and father. Linux advocating geek. Co-Host on the AdminAdmin Podcast, occasional conference speaker.

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