Starbeamrainbowlabs

About

Hello!

I am a computer science student who is in their third year at Hull University. I started out teaching myself about various web technologies, and then I managed to get a place at University, where I am now. I've done a year in industry too, which I found to be particuarly helpful in learning about the workplace and the world.

I currently know C# + Monogame / XNA (+ WPF), HTML5, CSS3, Javascript (ES6 + Node.js), PHP, C / C++ (mainly for Arduino), and a bit of Python. Oh yeah, and I can use XSLT too.

I love to experiment and learn about new things on a regular basis. You can find some of the things that I've done in the labs and code sections of this website, or on GitHub. My current projects are Pepperminty Wiki, an entire wiki engine in a single file (the source code is spread across multiple files - don't worry!), and Nibriboard (a multi-user real-time infinite whiteboard), although the latter is in its very early stages.

I can also be found in a number of other different places around the web. I've compiled a list of the places that I can remember below.

I can be contacted at the email address webmaster at starbeamrainbowlabs dot com. Suggestions, bug reports and constructive criticism are always welcome.

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Latest Post

Automatically rotating log files on Linux

I'm rather busy at the moment with University, but I thought I'd post about Linux's log rotating system, which I've discovered recently. This post is best read as a follow-up to my earlier post, creating a system service with systemd, in which I talk about how to write a systemd service file - and how to send the output of your program to syslog - which will put it in /var/log for you.

Log rotating is the practice of automatically renaming and moving log files around at regular intervals - and keeping only so many log files at once. For example, I might define the following rules:

  • Rotate the log files every week
  • Keep 10 log files in total
  • Compress log files past the 2nd one

This would yield me a set of log files like this, for instance:

dpkg.log
dpkg.log.1
dpkg.log.2.gz
dpkg.log.3.gz
dpkg.log.4.gz
dpkg.log.5.gz
dpkg.log.6.gz
dpkg.log.7.gz
dpkg.log.8.gz
dpkg.log.9.gz
dpkg.log.10.gz

When the logs are next rotated, the last one is deleted and all the rest are renamed sequentially - like 10 in the bed.

Compressing log files is good for saving space, but in order to read them again we have to fiddle about with zcat / gzip.

The log rotating system on Linux is a cron job that runs at regular intervals - it doesn't run as a system service. It's configured by a series of files in /etc/logrotate.d/ - 1 for each service that has log files that want rotating automatically. Here's an example definition file:

/var/log/rhinoreminds/rhinoreminds.log {
    rotate 12
    weekly
    missingok
    notifempty
    compress
    delaycompress
}

Basically you specify the filename first, and then a bunch of directives to tell it what to do inside { }. The above is for RhinoReminds, an XMPP reminder bot I've written, and defines the following:

  • Keep 12 log files in the rotation cycle
  • Rotate the logs every week
  • It's ok if the log file doesn't exist
  • Don't rotate the log file if it's empty
  • Compress log files on rotation if they aren't already
  • .....but delay this by 1 rotation cycle

Very cool! This should produce the following:

/var/log/rhinoreminds/rhinoreminds.log
/var/log/rhinoreminds/rhinoreminds.log.1
/var/log/rhinoreminds/rhinoreminds.log.2.gz
/var/log/rhinoreminds/rhinoreminds.log.3.gz
/var/log/rhinoreminds/rhinoreminds.log.4.gz
/var/log/rhinoreminds/rhinoreminds.log.5.gz
/var/log/rhinoreminds/rhinoreminds.log.6.gz
/var/log/rhinoreminds/rhinoreminds.log.7.gz
/var/log/rhinoreminds/rhinoreminds.log.8.gz
/var/log/rhinoreminds/rhinoreminds.log.9.gz
/var/log/rhinoreminds/rhinoreminds.log.10.gz
/var/log/rhinoreminds/rhinoreminds.log.11.gz
/var/log/rhinoreminds/rhinoreminds.log.12.gz

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