⊕ Usage

set
set -- [ arguments ... ]
set [ -short-options ] [ -o long-option ] [ arguments ... ]
set [ +short-options ] [ +o long-option ] [ arguments ... ]
set -o
set +o

⊕ Purpose

 

To print the names and values of all current shell variables; to set or unset the value of shell options (which change the way that the shell behaves); and to change the values of the positional parameters.

⊕ Major options

 

See text.

⊕ Behavior

 

With no options or arguments, print the names and values of all shell variables in a form that can later be reread by the shell.

 

With -- and arguments, replace the positional parameters with the supplied arguments.

 

With short-form options that begin with a -, or long-form options that begin with -o, enable particular shell options. Additional nonoption arguments set the positional parameters. See text for details.

 

With short-form options that begin with a +, or long-form options that begin with +o, disable particular shell options. See text for details.

 

A single -o prints the current settings of the shell options "in an unspecified format." ksh93 and bash both print a sorted list, where each line is an option name and the word on or off:

$ set -o From bash
allexport off

 

A single +o prints the current settings of the shell options in a way that they may be later reread by the shell to achieve the same set of option settings.

⊕ Caveats

 

Real shells have additional short and long options, above and beyond the ones described in Table 7-10. Details are given in Chapter 14. Don't use them if portability is a major concern.