Tom Ryder

Systems administrator, software developer, and technical writer, living in New Zealand.

Joan Eleanor Ryder 1934–2024

Email: (PGP)


Bash Quick Start Guide

In , my book was published with Packt Publishing. It’s a crash course in writing and reading Bash and POSIX‐fearing shell script in general. The aim of the book is to demystify shell and make it pleasant and expressive to write. I answered an author questionnaire for it.

This was the only book I could find that lays out best practises for bash scripting, such as proper quoting, variable naming, and parameter expansion. There are many books that will show you a lot of interesting script examples but they’ll also teach you bad habits that might get you into trouble down the road. This would be a great first book for anyone looking to write safe, portable scripts. Highly recommended!

— user “Kinger”

Tom’s careful grounding in the fundamentals of how and why things work in Bash is valuable both as an introduction for newcomers and in refining the skills of experienced users. Even if you have been around Bash for a while you will learn new and useful things from this book, and probably almost immediately.

Definitely the Bash book I was looking for 15 years ago.

—Nick Jensen

Reference: . Bash Quick Start Guide. BirminghamPackt Publishing, Limited, . Print. ISBN978-1-78953-883-0

Nagios Core Administration Cookbook

In , the second edition of my book was published with Packt Publishing. It explains how to set up Nagios Core to solve various monitoring problems. The first edition from reviews pretty well on Amazon.

I wish I had this book over a year and a half ago when I first started learning about this software. The topics are extremely easy to follow and start from the very basics to advanced topics including redundant servers and monitoring Nagios’ own performance.

—Richard J. Breiten

This book covers every corner of Nagios Core needed for a healthy setup. If this is your first time using Nagios Core, this is the book for you. Even if you have a working environment, this is a great resource to verify best practices are being followed—in terms of both security and usability.

— user “Andrew”

Reference: . Nagios Core Administration Cookbook ‐ Second Edition. BirminghamPackt Publishing, Limited, . Print. ISBN978-1-78588-933-2


I maintain a blog called , with posts mostly about Unix command line tools. Its byline is Systems, Tools, and Terminal Science. There are reader translations and e-book compilations of many of the articles around the web. Posts have featured in magazines such as BSD Magazine and Hacker Monthly.

Some popular articles:


I’ve contributed articles for the Vim enthusiasts’ website :


I publish code on my cgit instance. I’m particularly interested in C, Perl, Python, and Unix shell script programming, especially for the purposes of automation, reporting, and monitoring. I contribute Perl modules to CPAN, Python modules to PyPI, and have a blog on I also write a lot of PHP and JavaScript; I started my technical career as a web developer, but most of my web development is for internal tools now. I’m comfortable adapting to whatever stack is needed for a given project.

I write a lot of Nagios monitoring plugins. I publish some of them on Nagios Exchange. I also write a fair bit of Vim script for the text editor Vim, mostly just for fun; I publish plugins, filetype plugins, and colour schemes on

Here’s a list of some of the more interesting/useful/complete projects:

Scripts and configuration files for Unix‐like systems.
Find duplicate files efficiently using Perl core modules.
check_nrpe_cluster Nagios Exchange
Plugin for Nagios/Icinga to perform multiple NRPE checks and return a status based on the aggregated results.
check_speedtest_servers Nagios Exchange
Plugin for Nagios/Icinga to check whether a specified Ookla Speedtest server is in the public server list.
Brick‐stupid wrapper around Unix crypt(3) for quick prototyping on the command line.
List::Breakdown CPAN
Perl module to copy a list into named sub‐lists depending on test outcomes; an expressive shortcut for multiple named calls to the grep builtin.
Mail::Run::Crypt CPAN
Perl module with an experimental command wrapper to sign, encrypt, and mail command output and errors. Previously named croncrypt.
Music::Lyrics::LRC CPAN
Perl module to manage timed lyrics in LRC format.
Shell scripts for command‐line interaction with a Nagios server via Checkmk Livestatus to save the hassle of using the CGI scripts.
Shell script wrapper for tasks to send appropriate passive Nagios service checks using the NSCA client.
Shell script for easy use of the ndiff(1) program included with the Nmap suite.
Shell script daemon to refresh a GnuPG public keyring slowly, in random order, with random waits between each refresh, looping indefinitely.
Find and play media from your collection in your shell, based on a lazy keyword search wrapper around find(1).
Persistent SSH daemon setup for Debian‐like systems using start-stop-daemon(8).
ssh-negotiate-term PyPI
SSH wrapper to downgrade TERM values gracefully in response to hostname patterns.
Vim distributions
Various customisations for the text editor Vim, including colour schemes, plugins, and enhanced filetype support.
Keep track of new remote tags for local repositories.
Little tool in C to print hex octets of UTF-8 strings to show how the characters in them are encoded.


I have most experience on Debian GNU/Linux and its ilk, but can work on pretty much any Unix‐like operating system. I’m also fond of OpenBSD.


I’ve contributed to:


Palmerston North Linux Users Group

I’ve made some presentations to the Palmerston North Linux Users Group, for which I act as Secretary. Slides from my presentations are available for download here.


BSD Magazine’s issue includes an interview with me alongside an Arabesque article. The interview content without a paywall is available courtesy of the editor.

There’s also an email interview with me from about text editor usage patterns on How I Vim.

I was cited in the journal Nature, in an article titled Five reasons why researchers should learn to love the command line, by Jeffrey M. Perkel.