Installing Counter Strike Source is relatively painless on Ubuntu server or any linux distro that you decide to use. You can follow the commands that are in bold exactly as they are written below and Counter Strike should be installed in no time.
1) mkdir srcds
2) cd srcds
3) wget http://www.steampowered.com/download/hldsupdatetool.bin
4) chmod +x hldsupdatetool.bin
5) ./hldsupdatetool.bin
6) ./steam –command update –game “Counter-Strike Source” – dir .
a. Make sure to have the period after the dir
b. You need to do this command until you start downloading content from the Valve repository. It took me about 3 tries for it to start connecting and updating.
7) This should download and update everything needed to run the server. The time it takes depends on the connection of the download, typically between 30 minutes to 3 hours.
8) Success!