1<html lang="en"> 2<head> 3<title>Environment - Debugging with GDB</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Debugging with GDB"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Running.html#Running" title="Running"> 9<link rel="prev" href="Arguments.html#Arguments" title="Arguments"> 10<link rel="next" href="Working-Directory.html#Working-Directory" title="Working Directory"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988-2013 Free Software Foundation, Inc. 14 15Permission is granted to copy, distribute and/or modify this document 16under the terms of the GNU Free Documentation License, Version 1.3 or 17any later version published by the Free Software Foundation; with the 18Invariant Sections being ``Free Software'' and ``Free Software Needs 19Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' 20and with the Back-Cover Texts as in (a) below. 21 22(a) The FSF's Back-Cover Text is: ``You are free to copy and modify 23this GNU Manual. 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Environment variables conventionally record such things as 54your user name, your home directory, your terminal type, and your search 55path for programs to run. Usually you set up environment variables with 56the shell and they are inherited by all the other programs you run. When 57debugging, it can be useful to try running your program with a modified 58environment without having to start <span class="sc">gdb</span> over again. 59 60 61<a name="index-path-122"></a> 62<dl><dt><code>path </code><var>directory</var><dd>Add <var>directory</var> to the front of the <code>PATH</code> environment variable 63(the search path for executables) that will be passed to your program. 64The value of <code>PATH</code> used by <span class="sc">gdb</span> does not change. 65You may specify several directory names, separated by whitespace or by a 66system-dependent separator character (‘<samp><span class="samp">:</span></samp>’ on Unix, ‘<samp><span class="samp">;</span></samp>’ on 67MS-DOS and MS-Windows). If <var>directory</var> is already in the path, it 68is moved to the front, so it is searched sooner. 69 70 <p>You can use the string ‘<samp><span class="samp">$cwd</span></samp>’ to refer to whatever is the current 71working directory at the time <span class="sc">gdb</span> searches the path. If you 72use ‘<samp><span class="samp">.</span></samp>’ instead, it refers to the directory where you executed the 73<code>path</code> command. <span class="sc">gdb</span> replaces ‘<samp><span class="samp">.</span></samp>’ in the 74<var>directory</var> argument (with the current path) before adding 75<var>directory</var> to the search path. 76<!-- 'path' is explicitly nonrepeatable, but RMS points out it is silly to --> 77<!-- document that, since repeating it would be a no-op. --> 78 79 <p><a name="index-show-paths-123"></a><br><dt><code>show paths</code><dd>Display the list of search paths for executables (the <code>PATH</code> 80environment variable). 81 82 <p><a name="index-show-environment-124"></a><br><dt><code>show environment </code><span class="roman">[</span><var>varname</var><span class="roman">]</span><dd>Print the value of environment variable <var>varname</var> to be given to 83your program when it starts. If you do not supply <var>varname</var>, 84print the names and values of all environment variables to be given to 85your program. You can abbreviate <code>environment</code> as <code>env</code>. 86 87 <p><a name="index-set-environment-125"></a><br><dt><code>set environment </code><var>varname</var> <span class="roman">[</span><code>=</code><var>value</var><span class="roman">]</span><dd>Set environment variable <var>varname</var> to <var>value</var>. The value 88changes for your program only, not for <span class="sc">gdb</span> itself. <var>value</var> may 89be any string; the values of environment variables are just strings, and 90any interpretation is supplied by your program itself. The <var>value</var> 91parameter is optional; if it is eliminated, the variable is set to a 92null value. 93<!-- "any string" here does not include leading, trailing --> 94<!-- blanks. Gnu asks: does anyone care? --> 95 96 <p>For example, this command: 97 98 <pre class="smallexample"> set env USER = foo 99</pre> 100 <p class="noindent">tells the debugged program, when subsequently run, that its user is named 101‘<samp><span class="samp">foo</span></samp>’. (The spaces around ‘<samp><span class="samp">=</span></samp>’ are used for clarity here; they 102are not actually required.) 103 104 <p><a name="index-unset-environment-126"></a><br><dt><code>unset environment </code><var>varname</var><dd>Remove variable <var>varname</var> from the environment to be passed to your 105program. This is different from ‘<samp><span class="samp">set env </span><var>varname</var><span class="samp"> =</span></samp>’; 106<code>unset environment</code> removes the variable from the environment, 107rather than assigning it an empty value. 108</dl> 109 110 <p><em>Warning:</em> On Unix systems, <span class="sc">gdb</span> runs your program using 111the shell indicated 112by your <code>SHELL</code> environment variable if it exists (or 113<code>/bin/sh</code> if not). If your <code>SHELL</code> variable names a shell 114that runs an initialization file—such as <samp><span class="file">.cshrc</span></samp> for C-shell, or 115<samp><span class="file">.bashrc</span></samp> for BASH—any variables you set in that file affect 116your program. You may wish to move setting of environment variables to 117files that are only run when you sign on, such as <samp><span class="file">.login</span></samp> or 118<samp><span class="file">.profile</span></samp>. 119 120 </body></html> 121 122