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Author: halfgaar

http://www.halfgaar.net/

Halfgaar is Wiebe. Wiebe is a contributing author on this weblog. He also has a lot of stuff (such as long, in-depth articles) on his personal website.

Wiebe works at YTEC, where he is a senior developer of customer-specific tailor-made software (“klantspecifieke maatwerk software“) for clients in a few select markets: wholesale, printing and healthcare.

PostgreSQL back-end for Ruby on Rails confusion

I just need to add a quick summary of what postgres back-end tool our Ruby on Rails application uses, and how we've configured it, because it's quite confusing... Read More »

Disabling SSH shell access for SVN users on a Linux/Unix system

A common problem is that Linux/Unix system administrators want to grant users access to SVN repositories, but prevent them from logging in on the shell. This can be accomplished quite easily. Read More »

Configuring a Debian satellite Exim server

A very common way to configure Exim on a Debian machine, is to make it a 'satellite'; a server which uses another SMTP server for sending and does not do local delivery, the latter being the difference with a 'smarthost'. It can be used by other computers in the network to send mail, but also by the machine itself, to send system notifications and such (one of my favorite apps, arpwatch, for example). Read More »

Crane camera shots with just a tripod

When shooting footage with a motion camera, one of the most important things to achieve to avoid it looking like a home-barbecue video, is stable motion, normally achieved with a crane. A simple way to achieve this, is by retracting one leg of your tripod, and then tilt it forwards and backwards. This video gives a good demonstration. The difference between the tripod shots, and the hand-held shots (the shots made to demonstrate the technique) is astounding. Read More »

Creating a bash fork bomb

Logged into a Unix machine? Does "ulimit -a" say that the max number of user processes is unlimited? Then type the following to crash the machine (provided it uses bash, or another shell with compatible syntax): Read More »

Setting up a domaincontroller with Samba

I occasionally have to set up a domain controller using Samba. There are a lot of guides and howto's available, but I made a step-by-step howto just for myself, and I thought it'd be smart to make it available on the internet for me to access anywhere. Read More »

Playing Quake3 in Linux with Skype or Teamspeak

I wanted to play a game of Quake3 against someone, and have Skype or Teamspeak open at the same time, for obvious reasons. Somehow, it reported the sound device being in use: "device or resource busy". This doesn't make any sense, because my card can do hardware mixing, and also because all other games work fine with Skype or Teamspeak active. Read More »

Mounting partititions residing inside a disk image

When you've read a disk with dd or ddrescue into an image file, one of the things you want to do is mount the partitions inside it. But, how does one do that? The answer is using losetup, with a bit of knowledge of partition offsets. Read More »

Rolling back a failed rdiff-backup session on a full partition

For those of you who use rdiff-backup, you may have run into the situation where the partition you're backing up to has no more space available. This is a very annoying situation, because rdiff-backup needs space to be able to roll back the session, so you're kind of stuck. You might think: "doesn't a decent file system have a reserved amount of space for the super user?" Yes, decent file systems do, but you'll often be running rdiff-backup as root, so that won't do any good. Read More »

Getting your terminal unstuck

Have you ever had your terminal freezing on you for a reason you can't identify? Fret no more, because this post will save your future login session. Read More »