<html lang="en"> <head> <title>Environment - Untitled</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="Untitled"> <meta name="generator" content="makeinfo 4.7"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Invocation.html#Invocation" title="Invocation"> <link rel="prev" href="Options.html#Options" title="Options"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <!-- This file documents the GNU linker LD (GNU Binutils) version 2.19. Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 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 1.1 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''.--> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family: serif; font-weight: normal; } --></style> </head> <body> <div class="node"> <p> <a name="Environment"></a>Previous: <a rel="previous" accesskey="p" href="Options.html#Options">Options</a>, Up: <a rel="up" accesskey="u" href="Invocation.html#Invocation">Invocation</a> <hr><br> </div> <h3 class="section">2.2 Environment Variables</h3> <!-- man begin ENVIRONMENT --> <p>You can change the behaviour of <span class="command">ld</span> with the environment variables <code>GNUTARGET</code>, <code>LDEMULATION</code> and <code>COLLECT_NO_DEMANGLE</code>. <p><a name="index-GNUTARGET-300"></a><a name="index-default-input-format-301"></a><code>GNUTARGET</code> determines the input-file object format if you don't use <span class="samp">-b</span> (or its synonym <span class="samp">--format</span>). Its value should be one of the BFD names for an input format (see <a href="BFD.html#BFD">BFD</a>). If there is no <code>GNUTARGET</code> in the environment, <span class="command">ld</span> uses the natural format of the target. If <code>GNUTARGET</code> is set to <code>default</code> then BFD attempts to discover the input format by examining binary input files; this method often succeeds, but there are potential ambiguities, since there is no method of ensuring that the magic number used to specify object-file formats is unique. However, the configuration procedure for BFD on each system places the conventional format for that system first in the search-list, so ambiguities are resolved in favor of convention. <p><a name="index-LDEMULATION-302"></a><a name="index-default-emulation-303"></a><a name="index-emulation_002c-default-304"></a><code>LDEMULATION</code> determines the default emulation if you don't use the <span class="samp">-m</span> option. The emulation can affect various aspects of linker behaviour, particularly the default linker script. You can list the available emulations with the <span class="samp">--verbose</span> or <span class="samp">-V</span> options. If the <span class="samp">-m</span> option is not used, and the <code>LDEMULATION</code> environment variable is not defined, the default emulation depends upon how the linker was configured. <p><a name="index-COLLECT_005fNO_005fDEMANGLE-305"></a><a name="index-demangling_002c-default-306"></a>Normally, the linker will default to demangling symbols. However, if <code>COLLECT_NO_DEMANGLE</code> is set in the environment, then it will default to not demangling symbols. This environment variable is used in a similar fashion by the <code>gcc</code> linker wrapper program. The default may be overridden by the <span class="samp">--demangle</span> and <span class="samp">--no-demangle</span> options. <!-- man end --> </body></html>