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