e285bfacc1
to the fact that the /bin/sh set command always sets the exit status to 0, so testing $? will not help discover if getopt found an error if getopt is used via "set -- `getopt ....`". (POSIX 1003.2 D11 draft says that the sh set command must return 0 as the exit status.) I think that POSIX is wrong or that is is not well enough specified to allow the result of the set to be the exit status of the getopt. But considering the sequential nature of execution, the set is done last and is the "last command" and therefore must be the one to set the exit status. At least there is a work-around for shell scripts.
120 lines
2.7 KiB
Groff
120 lines
2.7 KiB
Groff
.\" $NetBSD: getopt.1,v 1.7 1997/07/18 00:18:26 phil Exp $
|
|
.Dd June 21, 1993
|
|
.Dt GETOPT 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm getopt
|
|
.Nd parse command options
|
|
.Sh SYNOPSIS
|
|
.Nm args=\`getopt optstring $*\`
|
|
.Nm set \-\- \`getopt optstring $*\`
|
|
.Sh DESCRIPTION
|
|
.Nm Getopt
|
|
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 Getopt
|
|
will place
|
|
.Dq \-\-
|
|
in the arguments at the end of the options,
|
|
or recognize it if used explicitly.
|
|
The shell arguments
|
|
(\fB$1 $2\fR ...) 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.
|
|
.Sh EXAMPLE
|
|
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 o ,
|
|
which requires an argument.
|
|
.Pp
|
|
.Bd -literal -offset indent
|
|
args=\`getopt abo: $*\`
|
|
if test $? != 0
|
|
then
|
|
echo 'Usage: ...'
|
|
exit 2
|
|
fi
|
|
set \-\- $args
|
|
for i
|
|
do
|
|
case "$i"
|
|
in
|
|
\-a|\-b)
|
|
flag=$i; shift;;
|
|
\-o)
|
|
oarg=$2; shift; shift;;
|
|
\-\-)
|
|
shift; break;;
|
|
esac
|
|
done
|
|
.Ed
|
|
.Pp
|
|
This code will accept any of the following as equivalent:
|
|
.Pp
|
|
.Bd -literal -offset indent
|
|
cmd \-aoarg file file
|
|
cmd \-a \-o arg file file
|
|
cmd \-oarg -a file file
|
|
cmd \-a \-oarg \-\- file file
|
|
.Ed
|
|
.Pp
|
|
.St -p1003.2
|
|
mandates that the
|
|
.Nm sh
|
|
set command return the value of 0 for the exit status. Therefore,
|
|
the exit status of the
|
|
.Nm getopt
|
|
command is lost when
|
|
.Nm getopt
|
|
and the
|
|
.Nm sh
|
|
set command are used on the same line. The example given
|
|
is one way to detect errors found by
|
|
.Nm getopt .
|
|
.Sh SEE ALSO
|
|
.Xr sh 1 ,
|
|
.Xr getopt 3
|
|
.Sh DIAGNOSTICS
|
|
.Nm Getopt
|
|
prints an error message on the standard error output when it
|
|
encounters an option letter not included in
|
|
.Op optstring .
|
|
.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 getopt
|
|
rather than from the shell procedure containing the invocation
|
|
of
|
|
.Nm getopt ;
|
|
this again is hard to fix.
|
|
.Pp
|
|
The precise best way to use the
|
|
.Nm set
|
|
command to set the arguments without disrupting the value(s) of
|
|
shell options varies from one shell version to another. |