GETOPT(1) BSD Reference Manual GETOPT(1)
getopt - parse command options
set -- `getopt optstring $*`
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(3)); 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 whitespace. The special option "--" is used to delimit the end of the options. getopt will place "--" in the arguments at the end of the options, or recognize it if used explicitly. The shell arguments ($1 $2 ...) are reset so that each option is preceded by a "-" and in its own shell argument; each option argument is also in its own shell argument.
The following code fragment shows how one might process the arguments for a command that can take the options -a and -b, and the option -o, which requires an argument. # make the errorlevel test in the two lines below work with mksh set -o sh set -- `getopt abo: $*` if test $? != 0 then echo 'Usage: ...' exit 2 fi for i do case "$i" in -a|-b) flag=$i; shift;; -o) oarg=$2; shift; shift;; --) shift; break;; esac done This code will accept 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
getopt prints an error message on the standard error output when it en- counters an option letter not included in [optstring].
Written by Henry Spencer, working from a Bell Labs manual page. Behavior believed identical to the Bell version. Please do not use getopt in new scripts, use the getopts builtin in mksh(1) instead. See also the CAVEATS below for more reasons.
The return value of set -- `getopt abo: $*` will be 0 in POSIX-conformant shells, such as mksh(1). Only the Bourne shell and AT&T UNIX ksh88 have the historic behaviour of returning the exit code of getopt there.
Whatever getopt(3) has. Arguments containing whitespace or embedded shell metacharacters general- ly will not survive intact; this looks easy to fix but isn't. The error message for an invalid option is identified as coming from getopt rather than from the shell procedure containing the invocation of getopt; this again is hard to fix. The precise best way to use the set command to set the arguments without disrupting the value(s) of shell options varies from one shell version to another. MirOS BSD #10-current June 21, 1993 1
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