Articles tagged 'howto'

Family tree using Graphviz and Ruby

My dad spent a lot of time putting together a family database, currently containing about 12000 people covering both my parents ancestors as well as tracking forward to contain a lot of living descendants. Unfortunately, since he started this over 16-17 years ago it's been managed as a custom dBase III+ ...

Making Graphviz output pretty with XSL

NOTE: See the updated version of this stylesheet HERE

UPDATED: Example of the latest version here

A couple of years back I posted some about an XSL transformation I used to clean up Graphviz output to make my diagrams prettier. These days I use Omni Graffle for most of ...

Updated Graphviz tools on Github

I just added a new repository on GitHub containing the tools from my Graphviz / diagram related posts.
The repository can be found at:

These are the ones included and the appropriate articles:

Simple charts in Ruby using SVG::Graph

One thing that comes up time and time again when I mess around with a system, is quickly looking at frequencies of various things - for example disk usage by sub-directory, or referrer entries in my Apache access log.  Like this:

# cat /var/log/httpd/access_log | cut -d' ' -f11 | grep ...

Creating Graphviz graphs from Ruby arrays

As part of my compiler project I wanted a way to visualize the programs, and since the syntax tree (so far at least) is represented with plain Ruby arrays I decided to throw together a script to use Graphviz to generate some graphs. I've written about using Graphviz ...

5 simple ways to troubleshoot using Strace

I keep being surprised how few people are aware of all the things they can use strace for. It's always one of the first debug tools I pull out, because it's usually available on the Linux systems I run, and it can be used to troubleshoot such a wide variety of ...

How to beat comment spam (for now, anyway)

I've always loathed captcha's, and they've gotten progressively worse. But I've noticed some blogs seem to do reasonably well with just a single static word, presumably because most spammers won't customize things for a single blog unless you get a lot of traffic.

I also have a soft spot for an ...

When your Linux / iptables firewall randomly drops connections...

Yesterday our firewall at work started randomly dropping connections. It has probably happened a few times before, but been seemingly resolved before I had a chance to look at it.

Weirdly, some people in the office reported no problems, while others couldn't even get DNS lookups to work properly.

Looking at ...