4.3.7 Command line options

Some commands take arguments. The arguments starting with - or -- are called options and control the behavior of the command.

     $ date
     Mon Oct 27 23:02:09 CET 2003
     $ date -R
     Mon, 27 Oct 2003 23:02:40 +0100

Here the command-line argument -R changes the date command behavior to output RFC-2822 compliant date string.