Useful One Off Recipes
List directories from largest to smallest at the top level only. On older system h will not work and you must use k.
Long Running Processes
Look for long running processes,
Last searches back through the file /var/log/wtmp (or the file designated by the -f flag) and displays a list of all users logged in (and out) since that file was created.
Lastb is the same as last, except that by default it shows a log of the file /var/log/btmp, which contains all the bad login attempts.
Quck String Manipulation
Quick reference of manipulating standout,
Check if a file is corrupt,