KrazyWorks | Category Archive

Collectl & Colplot Sytem Performance Analysis Tools

August 26, 2015 – 11:17 am

It is not often that I run into Unix performance analysis tool that, a), I haven’t seen before and, b), is worth my attention. Collectl is both. It is a very useful combination of iostat, …

Installing Perl Modules with YUM

August 17, 2015 – 5:30 pm

Just a quick note on how to install Perl modules with YUM. Due to differences in the naming conventions, YUM package name for a Perl module may differ from the the module’s native name in …

Brief Guide to PDSh

August 17, 2015 – 12:53 pm

PDSh (Parallel Distributed Shell) is a high-performance parallel remote shell utility allowing you to execute commands on multiple remote hosts simultaneously. The utility was originally developed by LLNL and is currently available under GNU CPLv2. …

Dealing with Runaway Processes

July 14, 2015 – 10:46 pm

There is no official definition of a “runaway process”. Generally, it is a process that ignores its scheduled priority. It can also be a process that enters an infinite loop. Or it can be a process …

Find Available IP Addresses

June 18, 2015 – 10:58 am

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 Whatever spreadsheet you used to track IP allocations is likely out of date.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

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

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

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

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

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

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.

Detecting Synology NAS with nmap

May 29, 2015 – 3:07 pm

Just a quick note for myself on how to find Synology NAS servers on the network without having to use the bulky Windows utility that ships with these systems.

Dealing With Prolific Emailers

May 26, 2015 – 2:39 pm

So you come back from vacation, open Outlook and see thousands of unread emails. Who sends all this stuff? There’s an easy way to identify the sources of this background noise. In Outlook’s inbox, select …

Regex Collection

May 14, 2015 – 12:29 pm

Just a small collection of POSIX regular expressions that may come in handy for writing sysadmin scripts.

BASH History Control

May 12, 2015 – 12:01 pm

The standard output of the “history” command will show you the last one thousand commands executed by the user. This is useful, of course, but there are a few issues. Sometimes it’s important to know …

Verify Email SSL Certificate from CLI

May 8, 2015 – 10:36 am

Just a quick reference for validating SSL certs on mail servers. This is not something I have to do often, but when the need arises, I find myself googling the answer every single time. So …

Extending Swap on LVM2 Logical Volume

May 7, 2015 – 11:16 am

To grow swap on LVM you will need to temporarily disable the swap LV. This will leave without swap space, which may upset some applications (Oracle). So the first step should be to set up …

Faking the Uptime in Linux

May 4, 2015 – 10:05 pm

If, for whatever reason, you need to fake the Linux server uptime, there is a hacked kernel module you can use. The instructions are below.

Resetting HP ILO from OS

May 4, 2015 – 11:02 am

You can use ipmitool package in Linux to reset your HP server’s ILO password. The basic instructions are below.

Removing CTRL-M from Unix Files

April 16, 2015 – 4:44 pm

This is a simple but annoying and persistent problem: text files edited on Windows and the uploaded to Unix acquire the “^M” character at the end of each line. In my experience, this little problem …

Observium Agent Installation on Pidora

April 13, 2015 – 11:50 am

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Just some quick notes on installing Observium agent on Raspberry Pi running Pidora. Pretty much the same process applies to any Fedora-like flavor.

Log Event Time Distribution

April 2, 2015 – 11:04 am

When “once in a while” answer is insufficient and you need to know exactly how often a particular event occurs on the system, there are a few easy things you can try from command line.

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