getopt is used to break up options in command lines for easy parsing by shell procedures and to check for valid options. It recognizes supplementary code set characters in the argument given to optstring according to the locale specified in the LC_CTYPE environment variable (see LANG on environ(5)).
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 that 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.
Reset OPTIND to 1 when rescanning the options.
does not support
the part of Rule 8 of the command syntax standard
that permits groups of option-arguments following an
option to be separated by white space and quoted.
cmd -a -b -o "xxx z yy" file
is not handled correctly. To correct this deficiency, use the getopts command instead of getopt.
If an option that takes an option-argument is followed by a value that is the same as an option listed in optstring (referring to the earlier ``Examples'' section, but using the following command line: cmd -o -a file), 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 file argument.
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 file file
cmd -a -o arg file file
cmd -oarg -a file file
cmd -a -oarg -- file file