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March 2, 2022 – 2:00 pm

Books have been written on the subject of awk and sed. Here’s a small sample of commands I put together over the years that are useful for everyday system administration tasks. Most of these tasks …

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Article Archive for June 2015

Find Available IP Addresses

June 18, 2015 – 10:58 am
shell_0005

After a while, available IP addresses on the subnet may become hard to come by. Whatever spreadsheet you used to track IP allocations is likely out of date. Here’s a simple script that will scan …

Multi-Cluster Ganglia Configuration

June 17, 2015 – 11:28 am
ganglia_002

I’ve discussed Ganglia configuration and RHEL/CentOS installation in the past. The usual structure is where every node belongs to one cluster. Recently I ran into a requirement to have nodes assigned to more than one cluster. …

Enabling dmesg Timestamps in RHEL

June 12, 2015 – 5:04 pm
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By default, CentOS/RHEL dmesg timestamps are disabled. Here are the instructions to enable timestamps and a quick script to display time in a human-readable format.

Practical TShark Capture Filters

June 12, 2015 – 9:30 am
ethernet cables

The tshark is the command-line interface for Wireshark – a popular open-source network packet analyzer. A seemingly infinite variety of options make tshark an unlikely choice for casual use. Nevertheless, the power of CLI justifies the extra …

Raspberry Pi 2 OpenELEC Player

June 10, 2015 – 4:37 pm
raspberry_pi_openelec_player_0001

Just some quick documentation, mostly for myself, but feel free to try. This is a Raspberry Pi 2 with OpenELEC. The design is intended for overclocking, good wireless performance, and convenience of dual remotes. This …

Saving Postfix Messages

June 3, 2015 – 3:08 pm
postfix_logo

Sometimes for testing purposes you need to save all messages going through Postfix active queue. There are a couple of ways of doing this.

Simple Statistical Functions in Shell

June 3, 2015 – 12:01 pm
colorful shells

Here’s a small collection of basic statistical functions you can use in your shell scripts. This may come in handy when analyzing disk space, system performance, etc.