Linux

In Linux, replacing all instances of a string with another string is easy thanks to sed. A simple example is as follows:

To replace the string foo with the string bar in all .txt files:

While trying to edit a menu on a Drupal site, I found that none of my changes were being saved. Looking at the logs led me to the following error message:

Simply restarting MySQL did not fix things and it looked like I had to get my hands a li'l dirty.

Attempting to update flashplugin on Ubuntu Precise resulted in an error. Removing the package and reinstalling it resulted in the following:

After a recent server migration, I found that my MySQL instance was not starting up (on Debian Squeeze). A look in the logs revealed that MySQL was having issues with corrupt InnoDB tables and therefore refusing to start. A number of forums informed me to do the following.

In Linux, you can simplify some of your SSH commands using an SSH config file. For example, create a file named config in your ~/.ssh directory with something like the following:

I ran into this issue a couple of days ago and cannot recall the exact error message. However, the problem was effectively that aptitude could not install the new kernel update because my partition had apparently run out of space. An interrupted update to Klipper is one thing and the Linux kernel a whole 'nother kettle of fishies. Thinking that I simply needed to free up some space on my partition, I checked the current status via df.

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)