This is the default output of the munin load plugin.
I’ve patched it to add a permanent blue line indicating the number of cpu of the server. The resulted graph looks like this :

You can download the patched plugin here. It is tested with Linux and FreeBSD.

While monitoring a http/php server, I needed to do some statistics about php-cgi memory usage.
Playing with memory_limit in PHP, we wanted to know the average memory usage per php-cgi process. This is easily calculated with our best friend awk.
First, get the number of php running processes:
# ps aux | grep php-cgi | grep -v grep [...]

On some of freshly installed servers (Debian Etch), I encountered these error messages in /var/log/munin/munin-node.log:
Use of uninitialized value in eval {block} exit at /usr/sbin/munin-node line 456, <CHILD> line 8.
What a great error message
After digging into Google results, I found it was just a problem with host_name variable in the configuration. Default value is [...]

I encountered a problem last week with cron. crond was running but the jobs seems to not work. After debugging the crontab, I saw that on one job, the username was missing.
Nothing was written in the logs to say that there was a problem.
To avoid future problems, I wrote an alert for monit.
In my crontab, [...]