Swap file automatic loading in Linux
Solution 1:
As root in the command line:
echo "/dev/sda5 swap swap defaults 0 0" >> /etc/fstab
To have the change above take effect, run this command (still as root):
swapon -a
Alternatively: You can also open the file /etc/fstab in your favorite text editor (also as root) and add the following line to a new line at the bottom of that file:
/dev/sda5 swap swap defaults 0 0
Explanation
See this documentation on fstab.