GETOPT(1) BSD Reference Manual GETOPT(1)NAMEgetopt - parse command options
SYNOPSIS
set -- `getopt optstring $*`
DESCRIPTIONgetopt 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.
EXAMPLES
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
DIAGNOSTICSgetopt prints an error message on the standard error output when it en-
counters an option letter not included in [optstring].
SEE ALSOsh(1), getopt(3)HISTORY
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.
CAVEATS
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.
BUGS
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
