Linux/Unix Programming

Limits of handles etc:
http://www.moythreads.com/wordpress/2009/12/22/select-system-call-limitation/
Commands:
Touching all files in a directory including subdirectories :
find ./ -type f -exec touch "{}" \;

Viewing system name
uname
Setting environment variable:
export ENV_VAR=
Unsetting environment variable:
unset ENV_VAR
Viewing environment variables
env
Viewing processes running on the system
ps -a