mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-15 10:17:20 +00:00
132 lines
3.2 KiB
Groff
132 lines
3.2 KiB
Groff
.\" $FreeBSD$
|
|
.\"
|
|
.Dd April 3, 1999
|
|
.Dt GETOPT 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm getopt
|
|
.Nd parse command options
|
|
.Sh SYNOPSIS
|
|
.Nm args=\`getopt Ar optstring $*\`
|
|
; errcode=$?; set \-\- $args
|
|
.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.
|
|
.Ar 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
|
|
.Ql \-\-
|
|
is used to delimit the end of the options.
|
|
.Nm Getopt
|
|
will place
|
|
.Ql \-\-
|
|
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
|
|
.Ql \-
|
|
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
|
|
.Fl a
|
|
and
|
|
.Fl b ,
|
|
and the option
|
|
.Fl o ,
|
|
which requires an argument.
|
|
.Pp
|
|
.Bd -literal -offset indent
|
|
args=\`getopt abo: $*\`
|
|
# you should not use \`getopt abo: "$@"\` since that would parse
|
|
# the arguments differently from what the set command below does.
|
|
if [ $? != 0 ]
|
|
then
|
|
echo 'Usage: ...'
|
|
exit 2
|
|
fi
|
|
set \-\- $args
|
|
# You cannot use the set command with a backquoted getopt directly,
|
|
# since the exit code from getopt would be shadowed by those of set,
|
|
# which is zero by definition.
|
|
for i
|
|
do
|
|
case "$i"
|
|
in
|
|
\-a|\-b)
|
|
echo flag $i set; sflags="${i#-}$sflags";
|
|
shift;;
|
|
\-o)
|
|
echo oarg is "'"$2"'"; oarg="$2"; shift;
|
|
shift;;
|
|
\-\-)
|
|
shift; break;;
|
|
esac
|
|
done
|
|
echo single-char flags: "'"$sflags"'"
|
|
echo oarg is "'"$oarg"'"
|
|
.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
|
|
.Pp
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr sh 1 ,
|
|
.Xr getopt 3
|
|
.Sh DIAGNOSTICS
|
|
.Nm Getopt
|
|
prints an error message on the standard error output and exits with
|
|
status > 0 when it encounters an option letter not included in
|
|
.Ar optstring .
|
|
.Sh HISTORY
|
|
Written by
|
|
.An Henry Spencer ,
|
|
working from a Bell Labs manual page.
|
|
Behavior believed identical to the Bell version. Example changed in
|
|
.Fx
|
|
version 3.2 and 4.0.
|
|
.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. People trying to fix
|
|
.Nm getopt
|
|
or the example in this manpage should check the history of this file
|
|
in
|
|
.Fx .
|
|
.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.
|
|
.Pp
|
|
Each shellscript has to carry complex code to parse arguments halfway
|
|
correcty (like the example presented here). A better getopt-like tool
|
|
would move much of the complexity into the tool and keep the client
|
|
shell scripts simpler.
|