Martin Michlmayr
A NSLU2 from the front

Tips and tricks for Debian on the Linksys NSLU2

Controlling the LEDs and beeper

You can use the tool leds to control the LEDs and beeper. Typing leds without any arguments will show a help screen.

To control the beeper, you can also install the beep package and then run:

beep -e /dev/input/event0

beep can do a lot of things. For example, the following command will result in three beeps:

beep -e /dev/input/event0 -f 220 -l 500 -d 500 -r 3

Use power button to shut down system

By default, Debian will reboot the NSLU2 when you press the power button. If you want your NSLU2 to shut down when you press the button, you have to edit /etc/inittab. Look for a line like this:

ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -r now

and replace -r now with -h now. Make sure to run the following command to reload the file:

telinit q

Upgrading from Debian 6.0 (squeeze) to 7 (wheezy)

Here are some notes regarding upgrades from Debian 6.0 to 7:

Using UUIDs to reference disks

Debian 5.0 (lenny) uses names like /dev/sda1 to refer to your disk but there is no guarantee for device ordering with USB devices. This means that when you connect a second drive, your sda device might (or might not) become sdb, causing Debian to fail to boot because it's trying to access the wrong drive.

The solution for this problem is to disconnect the second drive, boot into Debian and convert /etc/fstab to use UUID (a unique ID for each partition) or LABEL (a name for each partition) instead of device names. To use UUID, do the following to find out the UUID for each partition (we'll use sda1 in the example):

cd /dev/disk/by-uuid
ls -l | grep sda1
[...] 683dbecd-1669-4210-bf29-fde6187261ba -> ../../sda1

Now edit /etc/fstab and replace the entry for sda1 with the UUID:

UUID=683dbecd-1669-4210-bf29-fde6187261ba /boot ext2 defaults 0 2

You have to do the same for all partitions listed in /etc/fstab. Finally, make a backup of your flash and then generate the initramfs. This is necessary because the name of the root device is stored in the initramfs.

cat /dev/mtdblock* > nslu2-backup
update-initramfs -u

Make sure you do this with only one disk connected. When Debian boots successfully with one disk using UUID, you can go ahead and add the second drive.

By the way, when upgrading from Debian 5.0 to 6.0, the upgrade process will automatically convert your /etc/fstab to UUIDs. However, the tar ball of Debian provided here still use /dev/sda1-style names.