PC Tips & Tricks

Here are 5 shell scripts you might find useful:

1. Dump a MySQL database and gzip the result =>[download#4]
2. Find duplicate files in a folder (it works even if the duplicate files have different names, which can be be helpful for mp3 files) =>[download#5]

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“Nagios® is an Open Source host, service and network monitoring program.” (from nagios.org)

Nagios has a lot of features, making it a very powerful monitoring tool. Some of the major features are listed below:

• Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)
• Monitoring of host resources (processor load, disk and memory usage, running processes, log files, etc.)
• Simple plugin design that allows users to easily develop their own host and service checks
• Ability to define network host hierarchy, allowing detection of and distinction between hosts that are down and those that are unreachable
• External command interface that allows on-the-fly modifications to be made to the monitoring and notification behavior through the use of event handlers, the web interface, and third-party applications
• Web interface for viewing current network status, notification and problem history, log file, etc.

Installing Nagios

In FreeBSD you can install from ports. (/usr/ports/net-mgmt/nagios*). Some Linux distributions also include Nagios.

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If you want to make a low-cost server with a RAID capabilities and don’t want to invest in a hardware RAID solution, gmirror is a good choice. You can use it to add a disk and create a mirror even on your existing server running FreeBSD 6 or 7.

In my example I have at start an 8 GB hard disk where I installed FreeBSD 7 (/dev/ad0).

The first thing to do is to add another hard disk with the same size (or bigger than the existing one) and boot the OS.

Now you have to create the mirror. For this you can use:

gmirror label -v -b round-robin gm0 /dev/ad0

If /dev/ad0 is the disk where the OS is installed (like in our example) then you will get an error because you are not allowed to write the metadata on a disk mounted for write. To solve this you must use sysctl:

sysctl kern.geom.debugflags=16

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Access control lists are extended attributes used to improve ability to control the access of files. They allow permissions to be set for individual groups and users and not just the owning user, owning group, and all other users.

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