Command options

You can invoke commands with one or more options or with none at all. Options modify the
way in which a command functions. They generally consist of a single letter. In the
command syntax they are either shown exactly as you have to enter them (in bold type) or
are collectively identified as "option" (in normal type).

The following rules generally apply when you enter more than one option:

• The order in which you list the options is immaterial.

• Options without arguments can be entered in two ways:

  • singly, e.g.: cmd -a -b -c

  • grouped, e.g.: cmd -abc

• Options that require an argument, for example -dargument or -f argument, cannot be combined with those that do not. Such options must be entered individually, with blanks (' ') to separate them:

  cmd -abc -dargument -f argument

• Options and option combinations are introduced by a minus sign (-): -abc.

• Two hyphens (--) may be used to indicate the end of the options. You need to use -- if the first argument begins with -.

Most commands output a usage message if they are called with an incorrect option. The usage message tells you which options and operands can be used in conjunction with a command call.

Example: Output of a usage message when an incorrect option is specified

$ ls -y
ls: Illegal option -- y

ls: Usage: ls -1RadCxmnlogrtucpFbqisfLe [files]