Usage statements

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Usage statements are a way to represent command syntax and consist of symbols such as brackets ([ ]), braces ({ }), and vertical bars (|).

The following is a sample of a usage statement for the unget command:

unget [ -rSID ] [ -s ] [ -n ]  File ...

The following conventions are used in the command usage statements:
  • Items that must be entered literally on the command line are in bold. These items include the command name, flags, and literal characters.
  • Items representing variables that must be replaced by a name are in italics. These items include parameters that follow flags and parameters that the command reads, such as Files and Directories.
  • Parameters enclosed in brackets are optional.
  • Parameters enclosed in braces are required.
  • Parameters not enclosed in either brackets or braces are required.
  • A vertical bar signifies that you choose only one parameter. For example, [ a | b ] indicates that you can choose a, b, or nothing. Similarly, { a | b } indicates that you must choose either a or b.
  • Ellipses ( ... ) signify the parameter can be repeated on the command line.
  • The dash ( - ) represents standard input.