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Command: getopt | Section: 1 | Source: OpenBSD | File: getopt.1
GETOPT(1) FreeBSD General Commands Manual GETOPT(1)
NAME
getopt - parse command options
SYNOPSIS
getopt optstring $*
DESCRIPTION
The getopt utility cannot handle option arguments containing whitespace;
consider using the standard getopts shell built-in instead.
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. However, if a letter is followed by
two colons, the argument is optional and may not be separated by
whitespace - this is an extension not covered by POSIX. 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.
args=`getopt abo: $*`
if [ $? -ne 0 ]
then
echo 'Usage: ...'
exit 2
fi
set -- $args
while [ $# -ne 0 ]
do
case "$1"
in
-a|-b)
flag="$1"; 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
DIAGNOSTICS
getopt prints an error message on the standard error output when it
encounters an option letter not included in optstring.
SEE ALSO
sh(1), getopt(3)
HISTORY
Written by Henry Spencer, working from a Bell Labs manual page. Behavior
believed identical to the Bell version.
CAVEATS
Note that the construction
set -- `getopt optstring $*`
is not recommended, as the exit value from set will prevent the exit
value from getopt from being determined.
BUGS
Whatever getopt(3) has.
Arguments containing whitespace or embedded shell metacharacters
generally 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.
FreeBSD 14.1-RELEASE-p8 May 4, 2021 FreeBSD 14.1-RELEASE-p8