An alias is a short command that calls a longer, more complicated command. It's also much shorter. To use any of these aliases, add them as a new line in your .login file. The .login file is a script, a list of commands that run every time you log on. And here's my favorite.
Related programs are who and w .
But these programs give you a list of the hundreds of people on line at a given time, most of whom are stangers. To use it, you need a file in your home directory named .dwrc . It's a good thing just to be able to type when you're bored. Here's a command that will return someone' s name based on their post-office box number.