Mac OS X - Unix Hints
Many people think its very "un-Mac" to have a Unix command line in your Mac, but I think of it as having the most powerful utility program available anywhere as a backup if the GUI (standard graphical) utilities and tools can't do the job. You definitely don't have to use Unix to use Mac OS X but if you know a bit of Unix its really useful, especially if you do support, programming, etc.
I should have mentioned that Unix is the operating system that Mac OS X is built on top of. Traditionally Unix has been used for large multi-user machines, servers, super-computers and high-end workstations. A variant of Unix, called Linux, is also quite popular for servers and as a workstation OS, but Apple is the first company to make the power of Unix available to everyone. I haven't used Unix for years so I'm gradually re-building my skills. Below are a few really simple Unix commands and tricks that non-Unix experts might find useful.
Go to the first section for an introduction to using the terminal for entering basic Unix commands.