2.2.4 Adding Command Options

Many commands have options that invoke special features of the command. For example, the date command has the option -u, which expresses the date in Greenwich Mean Time instead of local time:

$ date -u
Mon Feb 3 11:06:51 GMT 1993
$

Most options are expressed as a single character preceded by a dash (-). Not all commands have options. Some commands have more than one. If you use more than one option for a command, you can either type the options separately (-a -b) or together (-ab).