Command-Line Cautions

The command line offers a very powerful tool for administering and troubleshooting a Mac OS X system. Using the command line, however, calls for great attention to detail and involves fewer safety nets than interacting with the system using the graphical interface.

Things to watch for when using the command line include the following:

• Shells don't provide an undo feature, and you can't retrieve deleted files from the Trash.

• The numeral 0 (zero) and the uppercase letter O, and the numeral 1 (one) and the lowercase letter l often look the same but rarely mean the same thing to a shell.

• Spaces in filenames need to be escaped from the shell.

• The man pages come in numbered sections. Sometimes you have to specify the command and also the name section number to display the page you want.

• Occasionally you might find a man page that is out-of-date.