\" $NetBSD: getopt.1,v 1.19 2010/01/24 20:13:28 dholland Exp $
Dd November 28, 2009
Dt GETOPT 1
Os
Sh NAME
Nm getopt
Nd parse command options
Sh SYNOPSIS
Li args=\`getopt optstring $*\`
Pp
Li set \-\- \`getopt optstring $*\`
Sh DESCRIPTION
Nm
is used to break up options in command lines for easy parsing by
shell procedures, and to check for legal options.
Op Optstring
is a string of recognized option letters (see
Xr 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 white space.
The special option
Dq \-\-
is used to delimit the end of the options.
Nm
will place
Dq \-\-
in the arguments at the end of the options,
or recognize it if used explicitly.
The shell arguments
Pq Ev $1 , Ev $2 , ...
are reset so that each option is
preceded by a
Dq \-
and in its own shell argument;
each option argument is also in its own shell argument.
Pp
Nm
should not be used in new scripts; use the shell builtin
Nm getopts
instead.
Sh EXAMPLES
The following code fragment shows how one might process the arguments
for a command that can take the options
Op a
and
Op b ,
and the option
Op c ,
which requires an argument.
Pp
Bd -literal -offset indent
args=\`getopt abc: $*\`
if [ $? \-ne 0 ]; then
echo 'Usage: ...'
exit 2
fi
set \-\- $args
while [ $# \-gt 0 ]; do
case "$1" in
\-a|\-b)
flag=$1
;;
\-c)
carg=$2; shift
;;
\-\-)
shift; break
;;
esac
shift
done
Ed
Pp
This code will accept any of the following as equivalent:
Pp
Bd -literal -offset indent
cmd \-acarg file file
cmd \-a \-c arg file file
cmd \-carg -a file file
cmd \-a \-carg \-\- file file
Ed
Pp
St -p1003.2
mandates that the
Xr sh 1
set command return the value of 0 for the exit status.
Therefore, the exit status of the
Nm
command is lost when
Nm
and the
Xr sh 1
set command are used on the same line.
The example given is one way to detect errors found by
Nm .
Sh DIAGNOSTICS
Nm
prints an error message on the standard error output when it
encounters an option letter not included in
Op optstring .
Sh SEE ALSO
Xr sh 1 ,
Xr getopt 3
Sh HISTORY
Written by Henry Spencer, working from a Bell Labs manual page.
Behavior believed identical to the Bell version.
Sh BUGS
Whatever
Xr getopt 3
has.
Pp
Arguments containing white space or embedded shell metacharacters
generally will not survive intact; this looks easy to fix but isn't.
Pp
The error message for an invalid option is identified as coming
from
Nm
rather than from the shell procedure containing the invocation
of
Nm ;
this again is hard to fix.
Pp
The precise best way to use the
Ic set
command to set the arguments without disrupting the value(s) of
shell options varies from one shell version to another.
