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Edit File: Conditional-Commands.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!-- This manual is for GNU Texinfo (version 6.8, 8 June 2021), a documentation system that can produce both online information and a printed manual from a single source using semantic markup. Copyright (C) 1988, 1990-1993, 1995-1999, 2001-2021 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". --> <title>Conditional Commands (GNU Texinfo 6.8)</title> <meta name="description" content="Conditional Commands (GNU Texinfo 6.8)"> <meta name="keywords" content="Conditional Commands (GNU Texinfo 6.8)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="texi2any"> <meta name="viewport" content="width=device-width,initial-scale=1"> <link href="index.html" rel="start" title="Top"> <link href="Command-and-Variable-Index.html" rel="index" title="Command and Variable Index"> <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> <link href="Conditionals.html" rel="up" title="Conditionals"> <link href="Conditional-Not-Commands.html" rel="next" title="Conditional Not Commands"> <style type="text/css"> <!-- a.copiable-anchor {visibility: hidden; text-decoration: none; line-height: 0em} a.summary-letter {text-decoration: none} blockquote.indentedblock {margin-right: 0em} div.display {margin-left: 3.2em} div.example {margin-left: 3.2em} kbd {font-style: oblique} pre.display {font-family: inherit} pre.format {font-family: inherit} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} span.nolinebreak {white-space: nowrap} span.roman {font-family: initial; font-weight: normal} span.sansserif {font-family: sans-serif; font-weight: normal} span:hover a.copiable-anchor {visibility: visible} ul.no-bullet {list-style: none} --> </style> </head> <body lang="en"> <div class="section" id="Conditional-Commands"> <div class="header"> <p> Next: <a href="Conditional-Not-Commands.html" accesskey="n" rel="next">Conditional Not Commands</a>, Up: <a href="Conditionals.html" accesskey="u" rel="up">Conditionally Visible Text</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p> </div> <hr> <span id="Conditional-Commands-1"></span><h3 class="section">15.1 Conditional Commands</h3> <p>Texinfo has an <code>@if<var>format</var></code> environment for each output format, to allow conditional inclusion of text for a particular output format. </p> <span id="index-ifinfo"></span> <p><code>@ifinfo</code> begins segments of text that should be ignored by TeX when it typesets the printed manual, and by <code>makeinfo</code> when not producing Info output. The segment of text appears only in the Info file and, for historical compatibility, the plain text output. </p> <span id="index-ifdocbook"></span> <span id="index-ifhtml"></span> <span id="index-ifplaintext"></span> <span id="index-iftex"></span> <span id="index-ifxml"></span> <p>The environments for the other formats are analogous: </p> <dl compact="compact"> <dt><span><code>@ifdocbook … @end ifdocbook</code></span></dt> <dd><p>Text to appear only in the DocBook output. </p> </dd> <dt><span><code>@ifhtml … @end ifhtml</code></span></dt> <dd><p>Text to appear only in the HTML output. </p> </dd> <dt><span><code>@ifplaintext … @end ifplaintext</code></span></dt> <dd><p>Text to appear only in the plain text output. </p> </dd> <dt><span><code>@iftex … @end iftex</code></span></dt> <dd><p>Text to appear only in the printed manual. </p> </dd> <dt><span><code>@ifxml … @end ifxml</code></span></dt> <dd><p>Text to appear only in the XML output. </p></dd> </dl> <p>The <code>@if…</code> and <code>@end if…</code> commands must appear on lines by themselves in your source file. The newlines following the commands are (more or less) treated as whitespace, so that the conditional text is flowed normally into a surrounding paragraph. </p> <p>The <code>@if…</code> constructs are intended to conditionalize normal Texinfo source; see <a href="Raw-Formatter-Commands.html">Raw Formatter Commands</a>, for using underlying format commands directly. </p> <p>Here is an example showing all these conditionals: </p> <div class="example"> <pre class="example">@iftex This text will appear only in the printed manual. @end iftex @ifinfo However, this text will appear only in Info and plain text. @end ifinfo @ifhtml And this text will only appear in HTML. @end ifhtml @ifplaintext Whereas this text will only appear in plain text. @end ifplaintext @ifxml Notwithstanding that this will only appear in XML. @end ifxml @ifdocbook Nevertheless, this will only appear in DocBook. @end ifdocbook </pre></div> <p>The preceding example produces the following line: </p> <p>And this text will only appear in HTML. </p> <p>Notice that you only see one of the input lines, depending on which version of the manual you are reading. </p> <span id="index-errormsg"></span> <p>In complex documents, you may want Texinfo to issue an error message in some conditionals that should not ever be processed. The <code>@errormsg{<var>text</var>}</code> command will do this; it takes one argument, the text of the error message. </p> <p>We mention <code>@errormsg{}</code> here even though it is not strictly related to conditionals, since in practice it is most likely to be useful in that context. Technically, it can be used anywhere. See <a href="External-Macro-Processors.html">External Macro Processors: Line Directives</a>, for a caveat regarding the line numbers which <code>@errormsg</code> emits in TeX. </p> </div> <hr> <div class="header"> <p> Next: <a href="Conditional-Not-Commands.html">Conditional Not Commands</a>, Up: <a href="Conditionals.html">Conditionally Visible Text</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p> </div> </body> </html>