Securely Remove Files

If you really want to make sure you have wiped a file from your hard drive, you are going to want to use srm instead of rm. The man page for srm gives the following description:

srm removes each specified file by overwriting, renaming, and truncating it before unlinking. This prevents other people from undeleting or recovering any information about the file from the command line.

h/t Dillon Hafer