bash shell
After many years of using bash - I found some handy tips/reminders here:
http://www.catonmat.net/blog/bash-one-liners-explained-part-one/
http://www.catonmat.net/blog/bash-one-liners-explained-part-two/
http://www.catonmat.net/blog/bash-one-liners-explained-part-three/
http://www.catonmat.net/blog/bash-one-liners-explained-part-four/
http://www.catonmat.net/blog/bash-one-liners-explained-part-five/
http://www.catonmat.net/blog/bash-one-liners-explained-part-six/