NAME

getopts, getoptcvt − parse command options

SYNOPSIS

getopts optstring name [arg ...]

/usr/lib/getoptcvt [−b] file

DESCRIPTION

getopts is used by shell procedures to parse positional parameters and to check for legal options.  It supports all applicable rules of the command syntax standard (see Rules 3-10, intro(1)). It should be used in place of the getopt(1) command. (See the WARNING, below.) 

optstring must contain the option letters the command using getopts will recognize; if a letter is followed by a colon, the option is expected to have an argument, or group of arguments, which must be separated from it by white space. 

Each time it is invoked, getopts will place the next option in the shell variable name and the index of the next argument to be processed in the shell variable OPTIND.  Whenever the shell or a shell procedure is invoked, OPTIND is initialized to 1. 

When an option requires an option-argument, getopts places it in the shell variable OPTARG. 

If an illegal option is encountered, ?  will be placed in name.

When the end of options is encountered, getopts exits with a non-zero exit status.  The special option “−−” may be used to delimit the end of the options. 

By default, getopts parses the positional parameters.  If extra arguments (arg ...) are given on the getopts command line, getopts will parse them instead.  /usr/lib/getoptcvt reads the shell script in file, converts it to use getopts(1) instead of getopt(1), and writes the results on the standard output.

−b the results of running /usr/lib/getoptcvt will be portable to earlier releases of the UNIX system.  /usr/lib/getoptcvt modifies the shell script in file so that when the resulting shell script is executed, it determines at run time whether to invoke getopts(1) or getopt(1).

So all new commands will adhere to the command syntax standard described in intro(1), they should use getopts(1) or getopt(3C) to parse positional parameters and check for options that are legal for that command (see WARNINGS, below). 

EXAMPLE

The following fragment of a shell program shows how one might process the arguments for a command that can take the options a or b, as well as the option o, which requires an option-argument:

while getopts abo: c
do
case $c in
a │ b)FLAG=$c;;
o)OARG=$OPTARG;;
\?)echo $USAGE
exit 2;;
esac
done
shift `expr $OPTIND − 1`

This code will accept any of the following as equivalent:

cmd −a −b −o "xxx z yy" file
cmd −a −b −o "xxx z yy" −− file
cmd −ab −o xxx,z,yy file
cmd −ab −o "xxx z yy" file
cmd −o xxx,z,yy −b −a file

SEE ALSO

intro(1), sh(1), getopt(3C). 

WARNING

Although the following command syntax rule (see intro(1)) relaxations are permitted under the current implementation, they should not be used because they may not be supported in future releases of the system. As in the EXAMPLE section above, a and b are options, and the option o requires an option-argument:

cmd −aboxxx file  (Rule 5 violation:  options with
      option-arguments must not be grouped with other options)
cmd −ab −oxxx file  (Rule 6 violation:  there must be
      white space after an option that takes an option-argument)

Changing the value of the shell variable OPTIND or parsing different sets of arguments may lead to unexpected results. 

DIAGNOSTICS

getopts prints an error message on the standard error when it encounters an option letter not included in optstring.

September 02, 1992