Ever wonder how to copy something from the command line into the Mac OS clipboard? If you want to copy/paste a files content (perhaps a log file or a conf file, etc) into the clipboard to use outside of the CLI, you can use the commands pbcopy and pbpaste. Example: I want to copy the contents of my public key to the clipboard (so I can send it to a server admin who will use it in allowing me to access their subversion repository).

All I would need to do is:
cat id_dsa.pub | pbcopy

(cat writes out the content and then it is piped (|) into the clipboard) This comes in handy!

A few simple commands to help make your life working with UNIX a little easier:

If you are looking for a certain programs, use:whereis. Example. You want to find out where ipfw is located. In the command line type whereis ipfw and whereis will spit out the location (/sbin/ipfw).
If you need to find a program or a file and you know what it is called, use:locate. Example. I know I want to uninstall MySQL, and I want to see every file that has mysql in the file path. In the command line, type locate MySQL and locate will spit out every file with MySQL in the file path. (Note, locate is case sensitive).