1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<!-- This file documents the GNU linker LD 4(GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29)) 5version 2.36.1. 6 7Copyright (C) 1991-2021 Free Software Foundation, Inc. 8 9Permission is granted to copy, distribute and/or modify this document 10under the terms of the GNU Free Documentation License, Version 1.3 11or any later version published by the Free Software Foundation; 12with no Invariant Sections, with no Front-Cover Texts, and with no 13Back-Cover Texts. A copy of the license is included in the 14section entitled "GNU Free Documentation License". --> 15<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> 16<head> 17<title>LD: Environment</title> 18 19<meta name="description" content="LD: Environment"> 20<meta name="keywords" content="LD: Environment"> 21<meta name="resource-type" content="document"> 22<meta name="distribution" content="global"> 23<meta name="Generator" content="makeinfo"> 24<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 25<link href="index.html#Top" rel="start" title="Top"> 26<link href="LD-Index.html#LD-Index" rel="index" title="LD Index"> 27<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> 28<link href="Invocation.html#Invocation" rel="up" title="Invocation"> 29<link href="Scripts.html#Scripts" rel="next" title="Scripts"> 30<link href="Options.html#Options" rel="previous" title="Options"> 31<style type="text/css"> 32<!-- 33a.summary-letter {text-decoration: none} 34blockquote.smallquotation {font-size: smaller} 35div.display {margin-left: 3.2em} 36div.example {margin-left: 3.2em} 37div.indentedblock {margin-left: 3.2em} 38div.lisp {margin-left: 3.2em} 39div.smalldisplay {margin-left: 3.2em} 40div.smallexample {margin-left: 3.2em} 41div.smallindentedblock {margin-left: 3.2em; font-size: smaller} 42div.smalllisp {margin-left: 3.2em} 43kbd {font-style:oblique} 44pre.display {font-family: inherit} 45pre.format {font-family: inherit} 46pre.menu-comment {font-family: serif} 47pre.menu-preformatted {font-family: serif} 48pre.smalldisplay {font-family: inherit; font-size: smaller} 49pre.smallexample {font-size: smaller} 50pre.smallformat {font-family: inherit; font-size: smaller} 51pre.smalllisp {font-size: smaller} 52span.nocodebreak {white-space:nowrap} 53span.nolinebreak {white-space:nowrap} 54span.roman {font-family:serif; font-weight:normal} 55span.sansserif {font-family:sans-serif; font-weight:normal} 56ul.no-bullet {list-style: none} 57--> 58</style> 59 60 61</head> 62 63<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> 64<a name="Environment"></a> 65<div class="header"> 66<p> 67Previous: <a href="Options.html#Options" accesskey="p" rel="previous">Options</a>, Up: <a href="Invocation.html#Invocation" accesskey="u" rel="up">Invocation</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> 68</div> 69<hr> 70<a name="Environment-Variables"></a> 71<h3 class="section">2.2 Environment Variables</h3> 72 73 74<p>You can change the behaviour of <code>ld</code> with the environment variables 75<code>GNUTARGET</code>, 76<code>LDEMULATION</code> and <code>COLLECT_NO_DEMANGLE</code>. 77</p> 78<a name="index-GNUTARGET"></a> 79<a name="index-default-input-format"></a> 80<p><code>GNUTARGET</code> determines the input-file object format if you don’t 81use ‘<samp>-b</samp>’ (or its synonym ‘<samp>--format</samp>’). Its value should be one 82of the BFD names for an input format (see <a href="BFD.html#BFD">BFD</a>). If there is no 83<code>GNUTARGET</code> in the environment, <code>ld</code> uses the natural format 84of the target. If <code>GNUTARGET</code> is set to <code>default</code> then BFD 85attempts to discover the input format by examining binary input files; 86this method often succeeds, but there are potential ambiguities, since 87there is no method of ensuring that the magic number used to specify 88object-file formats is unique. However, the configuration procedure for 89BFD on each system places the conventional format for that system first 90in the search-list, so ambiguities are resolved in favor of convention. 91</p> 92<a name="index-LDEMULATION"></a> 93<a name="index-default-emulation"></a> 94<a name="index-emulation_002c-default"></a> 95<p><code>LDEMULATION</code> determines the default emulation if you don’t use the 96‘<samp>-m</samp>’ option. The emulation can affect various aspects of linker 97behaviour, particularly the default linker script. You can list the 98available emulations with the ‘<samp>--verbose</samp>’ or ‘<samp>-V</samp>’ options. If 99the ‘<samp>-m</samp>’ option is not used, and the <code>LDEMULATION</code> environment 100variable is not defined, the default emulation depends upon how the 101linker was configured. 102</p> 103<a name="index-COLLECT_005fNO_005fDEMANGLE"></a> 104<a name="index-demangling_002c-default"></a> 105<p>Normally, the linker will default to demangling symbols. However, if 106<code>COLLECT_NO_DEMANGLE</code> is set in the environment, then it will 107default to not demangling symbols. This environment variable is used in 108a similar fashion by the <code>gcc</code> linker wrapper program. The default 109may be overridden by the ‘<samp>--demangle</samp>’ and ‘<samp>--no-demangle</samp>’ 110options. 111</p> 112 113<hr> 114<div class="header"> 115<p> 116Previous: <a href="Options.html#Options" accesskey="p" rel="previous">Options</a>, Up: <a href="Invocation.html#Invocation" accesskey="u" rel="up">Invocation</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="LD-Index.html#LD-Index" title="Index" rel="index">Index</a>]</p> 117</div> 118 119 120 121</body> 122</html> 123