104 lines
2.3 KiB
Groff
104 lines
2.3 KiB
Groff
.Dd June 21, 1993
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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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.Nm set \-\- \`getopt optstring $*\`
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.Sh DESCRIPTION
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.Nm Getopt
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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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);
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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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.B \-\-
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is used to delimit the end of the options.
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.Nm Getopt
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will place
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.B \-\-
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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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(\fB$1 $2\fR ...) are reset so that each option is
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preceded by a
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.B \-
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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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.Sh EXAMPLE
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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 o ,
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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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set \-\- \`getopt abo: $*\`
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if test $? != 0
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then
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echo 'Usage: ...'
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exit 2
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fi
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for i
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do
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case "$i"
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in
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\-a|\-b)
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flag=$i; shift;;
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\-o)
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oarg=$2; shift; shift;;
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\-\-)
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shift; break;;
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esac
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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 \-aoarg file file
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cmd \-a \-o arg file file
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cmd \-oarg -a file file
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cmd \-a \-oarg \-\- file file
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.Ed
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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 DIAGNOSTICS
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.Nm Getopt
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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 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 getopt
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rather than from the shell procedure containing the invocation
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of
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.Nm getopt ;
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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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.Nm 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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