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<html><head><title>Macros (UNIX in a Nutshell: System V Edition)</title><link rel="stylesheet" type="text/css" href="../style/style1.css" /><meta name="DC.Creator" content="Arnold Robbins" /><meta name="DC.Format" content="text/xml" scheme="MIME" /><meta name="DC.Language" content="en-US" /><meta name="DC.Publisher" content="O'Reilly & Associates, Inc." /><meta name="DC.Source" scheme="ISBN" content="1-56592-427-4" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="UNIX in a Nutshell: System V Edition" /><meta name="DC.Type" content="Text.Monograph" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" usemap="#banner-map" border="0" alt="Book Home" /><map name="banner-map"><area shape="rect" coords="1,-2,616,66" href="index.htm" alt="Book Title" /><area shape="rect" coords="629,-11,726,25" href="jobjects/fsearch.htm" alt="Search this book" /></map><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch20_03.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228" /><td align="right" valign="top" width="228"><a href="ch20_05.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><h2 class="sect1">20.4. Macros</h2><p><a name="IXT-20-123608" /><a name="unut-ch-20-ix-macros-for-make-utility" />This section summarizes internal macros, modifiers, string substitution, and special macros.</p><a name="unut-ch-20-sect-4.1" /><div class="sect2"><h3 class="sect2">20.4.1. Internal Macros</h3><table border="1" cellpadding="3"><tr><td><tt class="literal">$?</tt></td><td><p>The list of prerequisites that have been changed more recently than the current target. Can be used only in normal description file entries--not suffix rules.</p></td></tr><tr><td><tt class="literal">$@</tt></td><td><p>The name of the current target, except in description file entries for making libraries, where it becomes the library name. Can be usedboth in normal description file entries and in suffix rules.</p></td></tr><tr><td><tt class="literal">$$@</tt></td><td><p>The name of the current target. Can be used only to the right of the colon in dependency lines.(May not work on all versions of <tt class="literal">make</tt>.)</p></td></tr><tr><td><tt class="literal">$<</tt></td><td><p>The name of the current prerequisite that has been modified more recentlythan the current target. Can be used only in suffix rules and in the <tt class="literal">.DEFAULT:</tt> entry.</p></td></tr><tr><td><tt class="literal">$*</tt></td><td><p>The name--without the suffix--of the current prerequisite that hasbeen modified more recently than the current target. Can be used only insuffix rules.</p></td></tr><tr><td><tt class="literal">$%</tt></td><td><p>The name of the corresponding <tt class="literal">.o</tt> file when the current target is a library module. Can be used both in normal description file entriesand in suffix rules.</p></td></tr></table><p></div><a name="unut-ch-20-sect-4.2" /><div class="sect2"><h3 class="sect2">20.4.2. Macro Modifiers</h3><p>Macro modifiers are not available in all variants of <tt class="literal">make</tt>.</p><dl><dt><tt class="literal">D</tt></dt><dd>The directory portion of any internal macro name except <tt class="literal">$?</tt>. Valid uses are: </p><blockquote><pre class="code">$(*D) $$(@D)$(<D) $(%D)$(@D)</pre></blockquote></dd><dt><tt class="literal">F</tt></dt><dd>The file portion of any internal macro name except <tt class="literal">$?</tt>.Valid uses are:</p><blockquote><pre class="code">$(*F) $$(@F)$(<F) $(%F)$(@F)</pre></blockquote></dd></dl></div><a name="unut-ch-20-sect-4.3" /><div class="sect2"><h3 class="sect2">20.4.3. Macro String Substitution</h3><p>String substitution is not available in all variants of <tt class="literal">make</tt>.</p><dl><dt><tt class="literal">$(</tt><tt><em class="replaceable">macro</em></tt><tt class="literal">:</tt><tt><em class="replaceable">s1</em></tt><tt class="literal">=</tt><tt><em class="replaceable">s2</em></tt><tt class="literal">)</tt></dt><dd>Evaluates to the current definitionof <tt class="literal">$(</tt><em class="emphasis">macro</em></tt><tt class="literal">)</tt>,after substituting the string <em class="emphasis">s2</em></tt> for every occurrenceof <em class="emphasis">s1</em></tt>that occurs either immediately before a blank or tab, or at the end ofthe macro definition.</p></dd></dl></div><a name="unut-ch-20-sect-4.4" /><div class="sect2"><h3 class="sect2">20.4.4. Macros with Special Handling</h3><table border="1" cellpadding="3"><tr><td><tt class="literal">MAKEFLAGS</tt></td><td><p>Contains the flags inherited in the environment variable<a name="IXT-20-123609" />MAKEFLAGS, plus any command-line options.Used to pass the flags to subsequent invocations of <tt class="literal">make</tt>,usually via command lines in a <tt class="literal">makefile</tt> thatcontain <tt class="literal">$(MAKE)</tt>.</p></td></tr><tr><td><tt class="literal">SHELL</tt></td><td><p>Sets the shell that interprets commands.<a name="IXT-20-123610" />If this macro isn't defined in thedescription file, the value depends on your system.Some Unix implementations use the shell from the user's environment (as withother macros). Other implementations (including SVR4) set the default <tt class="literal">SHELL</tt> to <tt class="literal">/bin/sh</tt>.</p></td></tr><tr><td><tt class="literal">VPATH</tt></td><td><p>(Not available in all variants of <tt class="literal">make</tt>.)<a name="IXT-20-123611" />Specifies a list of directories to search for prerequisiteswhen not found in the current directory.</p></td></tr></table><p></div><hr width="684" align="left" /><div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch20_03.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch20_05.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">20.3. Description File Lines</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">20.5. Special Target Names</td></tr></table></div><hr width="684" align="left" /><img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" /><p><p><font size="-1"><a href="copyrght.htm">Copyright © 2003</a> O'Reilly & Associates. 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