Linux

Since I keep forgetting this shortcut, here it is for posterity. Activating GNU Screen's scrollback feature can be done by pressing CTRL + a + [. This is especially handy when you are using Screen from within PuTTY.

While a number of sites provide additional Vim-esque shortcuts to navigate within the buffer, I've been able to get by fine with just the navigational arrow keys on my keyboard.

This is my week of playing around with mail servers and I have been keeping an eye on the logs on a regular basis. I noticed that the auth.log was riddled with millions of these pointless (from my POV anyhow) log entries:

CRON: pam_unix(cron:session): session opened for user root by (uid=0)
CRON: pam_unix(cron:session): session closed for user root

While trying to debug a postfix authentication issue in Debian 6, I had to use testsaslauthd to test things out:
testsaslauthd -s smtp -u foo@example.com -p test

only to get the following error:
connect() : No such file or directory 0

This is apparently because a lot of people (and authors) follow the same guide for configuring postfix and saslauthd. One of the steps missing is to symlink and saslauthd directory to a location within postfix. To fix:

If you've ever worked with Debian or Ubuntu servers, you've very likely had to set up a firewall at some point or the other. However, any changes that are made are not saved and loaded if the server is ever rebooted. The following is a quick guide on how to get this happening:

(root or sudo access is required)

My upgrade from Lucid to Precise did not go well and I've been battling errors ever since. I ran into the following error when trying to reinstall the php5-gd extension for PHP:
No apport report written because MaxReports is reached already

After my upgrade from Lucid to Precise (and thereby, from MySQL 5.1 to 5.5), I found that my MySQL instance was not running. When I tried to start the service all I got back was that it had failed to start.

After an upgrade from Lucid to Precise, my PHP install started complaining about a library:

While I've got a hunch that the actual problem is related to issues I had during the upgrade, turning this error (and other similar ones) off is as simple as going into /etc/php5/conf.d and renaming the file, in this case gd.ini to something like gd.ini.bak.

I needed to upload the contents of a lengthy log file to a site earlier today. There was no option to simply attach the file. I was instead asked to just paste its contents. I suppose that I could have opened the file in an editor like Kate and copied its contents to the clipboard. But I became curious as to the possibility of accomplishing this from within the terminal. A little googling revealed the existence of a utility named xsel for this very purpose.

So I tried updating one of my boxen running the Lucid Kubuntu LTS to the new Precise Pangolin beta. During the upgrade, I received an error message stating that adobe-flashplugin could not be upgraded. I ignored it and continued with the upgrade and all went swimmingly. Once the upgrade was completed and I had rebooted, when I tried to run an apt-get update, I ran into an error with respect to the adobe-flashplugin package. When I tried to remove it, it did not work. As a stop-gap measure, I removed a number of packages that depended on it including Firefox and sun-java6.

If you've been working with Linux terminals for a while, you've invariably found that viewing a binary file tends to output a lot of hieroglyphic nonsense (when all you want to do is check its header) and for some petty collateral damage, rapes your screen by changing your command prompt and window title to more of the same gibberish. While a lot of people (*raises hand*) simply accept such rowdy behaviour as one of the vagaries of life and simple open a new terminal window or similar, this - as I found out a few minutes ago - can be fixed.