getopt is used to break up options in command lines for easy parsing by shell procedures and to check for legal options. optstring is a string of recognized option letters; see getopt.3c If a letter is followed by a colon, the option is expected to have an argument which may or may not be separated from it by white space. The special option -- is used to delimit the end of the options. If it is used explicitly, getopt recognizes it; otherwise, getopt generates it; in either case, getopt places it at the end of the options. The positional parameters ($1 $2 ...) of the shell are reset so that each option is preceded by a - and is in its own positional parameter; each option argument is also parsed into its own positional parameter.
set -- `getopt abo: $*` if [ $? != 0 ] then echo $USAGE exit 2 fi for i in $* do case $i in -a | -b) FLAG=$i; shift;; -o) OARG=$2; shift 2;; --) shift; break;; esac done
This code accepts any of the following as equivalent:
cmd -aoarg filename1 filename2 cmd -a -o arg filename1 filename2 cmd -oarg -a filename1 filename2 cmd -a -oarg -- filename1 filename2
Reset optind to 1 when rescanning the options.
getopt does not support the part of Rule 8 of the command syntax standard (see intro.1 that permits groups of option-arguments following an option to be separated by white space and quoted. For example,
is not handled correctly. To correct this deficiency, use the getopts command in place of getopt.
If an option that takes an option-argument is followed by a value that is the same as one of the options listed in optstring (referring to the earlier EXAMPLES section, but using the following command line: cmd -o -a filename, getopt always treats -a as an option-argument to -o; it never recognizes -a as an option. For this case, the for loop in the example shifts past the filename argument.
Created by unroff & hp-tools. © by Hans-Peter Bischof. All Rights Reserved (1997).
Last modified 21/April/97