Bash

http://ss64.com/bash/

http://www.nixp.ru/forum/%D0%9A%D0%BE%D0%BD%D1%81%D0%BE%D0%BB%D1%8C%D0%BD%D1%8B%D0%B5-%D0%B8%D0%BD%D1%81%D1%82%D1%80%D1%83%D0%BC%D0%B5%D0%BD%D1%82%D1%8B/Bash-If-then

http://www.opennet.ru/openforum/vsluhforumID1/9933.html

http://www.linuxconfig.org/bash-scripting-tutorial#9-bash-if--else--fi-statements

http://poplinux.ru/adv-bash/chapter-8.1.html