set -- Command

Set shell option flags and positional parameters
set [-ceiknstuvx [name ...] ] (Bourne shell)
set [[+-]aefhkmnuvx] [[+-]o name] (Korn shell)

set changes the options of the current shell and optionally sets the values
of positional  parameters.  This  command is  used implemented by  both the
Bourne and Korn shells; however, its syntax and options vary from one shell
to the other.

Bourne Shell

The shell  variable `$-'  contains the currently  set shell flags.   If the
optional name  list is given, set assigns the  positional parameters $1, $2
... to the given shell variables.

set recognizes the following options:

-c string
   Read shell commands from string.

-e Exit  on  any error  (command  not found  or  command returning  nonzero
   status) if the shell is not interactive.

-i The shell  is interactive, even if  the terminal is not  attached to it;
   print  prompt strings.   For a  shell reading  a script,  ignore signals
   SIGTERM and SIGINT.

-k Place all  keyword arguments into the  environment.  Normally, the shell
   places  only assignments  to variables  preceding  the command  into the
   environment.

-n Read commands but do not execute them.

-s Read  commands from  the standard  input and write  shell output  to the
   standard error.

-t Read and execute one command rather than the entire file.

-u If the actual value of a shell variable is blank, report an error rather
   than substituting the null string.

-v Print each line as it is read.

-x Print each command and its arguments as it is executed.

-  Cancel the -x -v options.

The shell executes set directly.

Korn Shell

set recognizes  the following options.  Preceding an  option with `-' turns
on the option; preceding it with `+' turns it off.

-a allexport: Automatically export all new variables.

-e errexit: Exit from the shell when non-zero status is received.

-f noglob: Do  not expand file names.  This globally  turns off the special
   meaning of characters `*' and `?'.

-h trackall: Automatically add all commands to the shell's hash table.

-k keyword: Recognize variable assignments anywhere in a command.

-m monitor: Enable job control.  See the Lexicon article on ksh for details
   on job control and how to use it.

-n noexec: Compile an input command, but do not execute it.

-o option
   Set option. set recognizes the following options:

   allexport
           Same as -a option, above.
   emacs   Turn on MicroEMACS-style editing of command lines.
   errexit
           Same as -e option, above.
   ignoreeof
           Tell the  shell not  to  exit when  reading EOF:  must use  exit
           command to exit from the shell.
   keyword
           Same as -k option, above.
   monitor
           Same as -m option, above.
   noexec  Same as -n option, above.
   noglob  Same as -f option, above.
   trackall
           Same as -h option, above.
   nounset
           Same as -u option, below.
   verbose
           Same as -v option, below.
   xtrace  Same as -x option, below.

-u nounset: Treat dollar-sign expansion of an unset variable as an error.

-v verbose: When  compiling a command,  echo its compiled  (i.e., expanded)
   version on the standard output before executing it.

-x xtrace: Echo simple commands while executing.

The shells execute set directly.

See Also

commands,
ksh,
sh,
unset

© 2012 by Stephen A. Ness