Redirect both stderr and stdout to somewhere (/dev/null perhaps?)
[command] > /dev/null 2>&1

If you hit ctrl-s in a terminal, it will not display anything you type.  
To get the terminal back to normal, hit ctrl-q

command line sequence:
for i in `seq -w 1 10`; do echo $i; done

to filter out text in a list:
ls * | grep -v 'ignorethis\|andthis\|thistoo'

To get color in the terminal add the following to your environment 
(this was in FreeBSD)
alias ls="ls -G"
export TERM=xterm-color

To avoid having duplicates in your command history, add the following to a 
bash configuration file:
export HISTIGNORE=\&
That way it will only store one copy of the command.

If you get error messages like "./script 16: unbalanced [" when you're using an 
if statement in your shell script, make sure there is a space after the [ 
and before the ] in the conditional.

To execute multiple commands with the find -exec option, use escaped ampersands:
find . -name '*.txt' -exec ls -l {} \&\& touch {} \;

Updated Nov 18, 2006