<?xml version="1.0" encoding="ISO8859-1"?>
<fpdoc-descriptions>
<!--  

   $Id: getopts.xml,v 1.2 2004/09/13 19:27:49 michael Exp $ 
   This file is part of the FPC documentation. 
   Copyright (C) 1997, by Michael Van Canneyt 
 
   The FPC documentation is free text; you can redistribute it and/or 
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 -->
<package name="rtl">
<module name="getopts">
<short>GNU compatible access to command-line options.</short>
<!-- \FPCexampledir{optex} -->
<descr>
<p>
This document describes the GETOPTS unit for Free Pascal. It was written for
linux by Michael Van Canneyt. It now also works for all supported platforms.
</p>
<p>
The getopts unit provides a mechanism to handle command-line options in
a structured way, much like the GNU getopts mechanism. It allows you to
define the valid options for you program, and the unit will then parse the
command-line options for you, and inform you of any errors.
</p>
</descr>

<element name="OptSpecifier">
<short>Character indicating an option on the command-line.</short>
</element>

<element name="Orderings">
<short>Command-line ordering options.</short>
</element>
<element name="Orderings.require_order">
<short>Don't touch the ordering of the command-line options</short>
</element>
<element name="Orderings.permute">
<short>Change command-line options.</short>
</element>
<element name="Orderings.return_in_order">
<short>Return options in the correct order.</short>
</element>


<element name="No_Argument">
<short>Specifies that a long option does not take an argument.</short>
</element>

<element name="Required_Argument">
<short>Specifies that a long option needs an argument.</short>
</element>

<element name="Optional_Argument">
<short>Specifies that a long option optionally takes an argument.</short>
</element>

<element name="EndOfOptions">
<short>Returned by <link id="getopt"/>,<link id="getlongopts"/> to indicate that
there are no more options.</short>
</element>

<element name="TOption">
<short>Long option description record</short>
<descr>
The <var>TOption</var> type is used to communicate the long options to
<link id="GetLongOpts"/>.
The <var>Name</var> field is the name of the option. <var>Has_arg</var>
specifies if the option
wants an argument, <var>Flag</var> is a pointer to a <var>char</var>, which
is set to
<var>Value</var>, if it is non-<var>nil</var>.
</descr>
</element>

<element name="TOption.Name">
<short>Long option name</short>
</element>
<element name="TOption.Has_arg">
<short>Does the option have arguments (values)</short>
</element>
<element name="TOption.Flag">
<short>Flag</short>
</element>
<element name="TOption.Value">
<short>Value to return when option is encountered</short>
</element>

<element name="POption">
<short>Pointer to <link id="TOption"/> record.</short>
</element>

<element name="OptArg">
<short>Set to the argument of an option, if the option needs one.</short>
</element>

<element name="Optind">
<short>Index of the current <var>paramstr()</var>.</short>
<descr>
when all options have been processed, <var>optind</var> is the index of the first
non-option parameter. This is a read-only variable. Note that it can become
equal to <var>paramcount+1</var>.
</descr>
</element>

<element name="OptErr">
<short>Indicates whether <var>getopt()</var> prints error messages.</short>
</element>

<element name="OptOpt">
<short>In case of an error, contains the character causing the error.</short>
</element>

<element name="GetLongOpts">
<short>Return next long option.</short>
<descr>
<p>
Returns the next option found on the command-line, taking into account long
options as well. If no more options are
found, returns <var>EndOfOptions</var>. If the option requires an argument, it is
returned in the <var>OptArg</var> variable.
</p>
<p>
<var>ShortOptions</var> is a string containing all possible one-letter options.
(see <link id="Getopt"/> for its description and use)
<var>LongOpts</var> is a pointer to the first element of an array of <var>Option</var> 
records, the last of which needs a name of zero length.  
</p>
<p>
The function tries to match the names even partially (i.e. <var>--app</var> 
will match e.g. the <var>append</var> option), but will report an error in case of
ambiguity.
If the option needs an argument, set <var>Has_arg</var> to
<var>Required_argument</var>, if the option optionally has an argument, set
<var>Has_arg</var> to <var>Optional_argument</var>. If the option needs no argument,
set <var>Has_arg</var> to zero.
</p>
<p>
Required arguments can be specified in two ways : 
</p>
<ol>
<li>Pasted to the option : <var>--option=value</var></li>
<li>As a separate argument : <var>--option value</var></li>
</ol>
<p>
Optional arguments can only be specified through the first method.
</p>
</descr>
<errors>
see <link id="Getopt"/>.
</errors>
<seealso>
<link id="Getopt"/>
</seealso>
</element>

<element name="Getopt">
<short>Get next short option.</short>
<descr>
<p>
Returns the next option found on the command-line. If no more options are
found, returns <var>EndOfOptions</var>. If the option requires an argument, it is
returned in the <var>OptArg</var> variable.
</p>
<p>
<var>ShortOptions</var> is a string containing all possible one-letter options.
If a letter is followed by a colon (:), then that option needs an argument.
If a letter is followed by 2 colons, the option has an optional argument.
If the first character of <var>shortoptions</var> is a <var>'+'</var> then options following a non-option are
regarded as non-options (standard Unix behavior). If it is a <var>'-'</var>,
then all non-options are treated as arguments of a option with character
<var>#0</var>. This is useful for applications that require their options in
the exact order as they appear on the command-line.
If the first character of <var>shortoptions</var> is none of the above, options
and non-options are permuted, so all non-options are behind all options.
This allows options and non-options to be in random order on the command
line.
</p>
</descr>
<errors>
 Errors are reported through giving back a <var>'?'</var> character. <var>OptOpt</var>
then gives the character which caused the error. If <var>OptErr</var> is
<var>True</var> then getopt prints an error-message to <var>stdout</var>.
</errors>
<seealso>
<link id="GetLongOpts"/>
</seealso>
<example file="optex/optex"/>
</element>

</module>
</package>
</fpdoc-descriptions>