getopts(1)
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getopts, getoptcvt Command
parse command options
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SYNTAX
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 the option letter 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 in optstring.
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 obtained by running /usr/lib/getoptcvt will be
portable to earlier releases of the DG/UX system.
/usr/lib/getoptcvt modifies the shell script in file so that
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getopts(1)
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) in the Programmer's Reference for the DG/UX System.
WARNING
Although the following command syntax rule (see intro(1))
exceptions are permitted under the current implementation, they
should not be used because they may not be supported in future
releases of the operating 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
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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.
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