Tips

If you make a change to a configuration file that needs to be reflected in your Linux boot process (such as mdadm.conf), you'll need to add it to your initramfs image.
This process varies by distribution (although most that I have used share the method I describe for Debian).

To update initramfs for Debian, run the command:
update-initramfs -u

In Fedora, run the command
dracut -f /boot/initramfs-currentimage
where initramfs-currentimage is replaced with the name of the image you are currently using.

Having recently moved my desktop to Fedora 15 I am now using Gnome Shell (more on this later). However, as with many of the configuration settings for Gnome, having focus follow mouse is no longer something you can set using installed graphical programs.
Fortunately, a one line command can rectify this for those of us who have become accustomed to using focus follows mouse (if you've never tried out focus follows, you should give it a shot for a week or so - you might be suprised out how nice it is).

You read that right. Today I had a partition with over 150 gigabytes of space left on it and a drive error reporting that said partition was full. Not only that, but this was an important partition for me, the one that I keep in a mirrored RAID because it stores the main copy of all my school work, programming and more, so I was very concerned about disk errors.

Sometimes when you are working in your Bash terminal, something goes wrong.
It might have been a program that output strange symbols, or maybe you ran the cat command on a binary file. But, no matter how it happened, it can make your terminal essentially useless until you restart it.
Fortunately, these problems were anticipated by the creators of Bash, and a command exists to set the terminal right.
Simply run reset and all should be well once more, returning you to the joy of the command line interface.

Now that you've set up APG and K9 to allow you to send and receive encrypted and signed emails from your Android phone, you've probably found that you need to import OpenPGP keys. Fortunately, if the keys you need can be found on keyservers, APG can download and import them for you.

If you are setting up a static IP address for a computer and need the gateway, finding the gateway address is simple, if you have a computer already setup on the network.
Below is a command which you can run on the configured computer to find the IP address of your gateway.

route -n

You should see at least one entry. If you see several, pick the entry under Gateway that is not 0.0.0.0
This number should be the IP address for your gateway.

In a home network, this is likely the same address as your router.

Last night as I was upgrading my new server, I ran the command
shutdown -h 00:10. Before the shutdown could complete, something interrupted my ssh session. As a result, when I tried to log back in, I received the following message:
The system is going down on Thu Jun 2 00:10:36 2011
and was immediately disconnect.
The problem was, it was already half an hour after the time in the message, and I had rebooted the server already.

I keep most of my files on my server because I've around a terabyte of space available. In order to access directories that I regularly need, I use NFS to share out the drives.

With a CPU or RAM intensive program running in terminal, sometimes you need to be able to pause the program in order work on something else for a bit, like browsing the web.