148 lines
6.4 KiB
HTML
148 lines
6.4 KiB
HTML
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<!DOCTYPE html>
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<html>
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<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>Command Line Handling (Guile Reference Manual)</title>
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<meta name="description" content="Command Line Handling (Guile Reference Manual)">
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<meta name="keywords" content="Command Line Handling (Guile Reference Manual)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content=".texi2any-real">
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<meta name="viewport" content="width=device-width,initial-scale=1">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Guile-Scripting.html" rel="up" title="Guile Scripting">
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<link href="Scripting-Examples.html" rel="next" title="Scripting Examples">
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<link href="The-Meta-Switch.html" rel="prev" title="The Meta Switch">
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<style type="text/css">
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a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em}
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</style>
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<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css">
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</head>
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<body lang="en">
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<div class="subsection-level-extent" id="Command-Line-Handling">
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<div class="nav-panel">
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<p>
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Next: <a href="Scripting-Examples.html" accesskey="n" rel="next">Scripting Examples</a>, Previous: <a href="The-Meta-Switch.html" accesskey="p" rel="prev">The Meta Switch</a>, Up: <a href="Guile-Scripting.html" accesskey="u" rel="up">Guile Scripting</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h4 class="subsection" id="Command-Line-Handling-1"><span>4.3.3 Command Line Handling<a class="copiable-link" href="#Command-Line-Handling-1"> ¶</a></span></h4>
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<p>The ability to accept and handle command line arguments is very
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important when writing Guile scripts to solve particular problems, such
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as extracting information from text files or interfacing with existing
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command line applications. This chapter describes how Guile makes
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command line arguments available to a Guile script, and the utilities
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that Guile provides to help with the processing of command line
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arguments.
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</p>
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<p>When a Guile script is invoked, Guile makes the command line arguments
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accessible via the procedure <code class="code">command-line</code>, which returns the
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arguments as a list of strings.
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</p>
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<p>For example, if the script
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</p>
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<div class="example">
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<pre class="example-preformatted">#! /usr/local/bin/guile -s
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!#
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(write (command-line))
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(newline)
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</pre></div>
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<p>is saved in a file <samp class="file">cmdline-test.scm</samp> and invoked using the command
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line <code class="code">./cmdline-test.scm bar.txt -o foo -frumple grob</code>, the output
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is
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</p>
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<div class="example">
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<pre class="example-preformatted">("./cmdline-test.scm" "bar.txt" "-o" "foo" "-frumple" "grob")
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</pre></div>
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<p>If the script invocation includes a <code class="code">-e</code> option, specifying a
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procedure to call after loading the script, Guile will call that
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procedure with <code class="code">(command-line)</code> as its argument. So a script that
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uses <code class="code">-e</code> doesn’t need to refer explicitly to <code class="code">command-line</code>
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in its code. For example, the script above would have identical
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behavior if it was written instead like this:
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</p>
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<div class="example">
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<pre class="example-preformatted">#! /usr/local/bin/guile \
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-e main -s
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!#
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(define (main args)
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(write args)
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(newline))
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</pre></div>
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<p>(Note the use of the meta switch <code class="code">\</code> so that the script invocation
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can include more than one Guile option: See <a class="xref" href="The-Meta-Switch.html">The Meta Switch</a>.)
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</p>
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<p>These scripts use the <code class="code">#!</code> POSIX convention so that they can be
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executed using their own file names directly, as in the example command
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line <code class="code">./cmdline-test.scm bar.txt -o foo -frumple grob</code>. But they
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can also be executed by typing out the implied Guile command line in
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full, as in:
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</p>
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<div class="example">
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<pre class="example-preformatted">$ guile -s ./cmdline-test.scm bar.txt -o foo -frumple grob
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</pre></div>
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<p>or
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</p>
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<div class="example">
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<pre class="example-preformatted">$ guile -e main -s ./cmdline-test2.scm bar.txt -o foo -frumple grob
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</pre></div>
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<p>Even when a script is invoked using this longer form, the arguments that
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the script receives are the same as if it had been invoked using the
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short form. Guile ensures that the <code class="code">(command-line)</code> or <code class="code">-e</code>
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arguments are independent of how the script is invoked, by stripping off
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the arguments that Guile itself processes.
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</p>
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<p>A script is free to parse and handle its command line arguments in any
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way that it chooses. Where the set of possible options and arguments is
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complex, however, it can get tricky to extract all the options, check
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the validity of given arguments, and so on. This task can be greatly
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simplified by taking advantage of the module <code class="code">(ice-9 getopt-long)</code>,
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which is distributed with Guile, See <a class="xref" href="getopt_002dlong.html">The (ice-9 getopt-long) Module</a>.
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</p>
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</div>
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<hr>
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<div class="nav-panel">
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<p>
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Next: <a href="Scripting-Examples.html">Scripting Examples</a>, Previous: <a href="The-Meta-Switch.html">The Meta Switch</a>, Up: <a href="Guile-Scripting.html">Guile Scripting</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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