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179 lines
8.9 KiB
HTML
179 lines
8.9 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2019 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Free Software" and "Free Software Needs
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Free Documentation", with the Front-Cover Texts being "A GNU Manual,"
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and with the Back-Cover Texts as in (a) below.
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(a) The FSF's Back-Cover Text is: "You are free to copy and modify
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this GNU Manual. Buying copies from GNU Press supports the FSF in
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developing GNU and promoting software freedom." -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Environment (Debugging with GDB)</title>
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<meta name="description" content="Environment (Debugging with GDB)">
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<meta name="keywords" content="Environment (Debugging with GDB)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Running.html#Running" rel="up" title="Running">
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<link href="Working-Directory.html#Working-Directory" rel="next" title="Working Directory">
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<link href="Arguments.html#Arguments" rel="prev" title="Arguments">
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<style type="text/css">
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a.summary-letter {text-decoration: none}
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blockquote.indentedblock {margin-right: 0em}
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blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
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blockquote.smallquotation {font-size: smaller}
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div.display {margin-left: 3.2em}
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div.example {margin-left: 3.2em}
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kbd {font-style: oblique}
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pre.display {font-family: inherit}
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pre.format {font-family: inherit}
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span.nolinebreak {white-space: nowrap}
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span.roman {font-family: initial; font-weight: normal}
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span.sansserif {font-family: sans-serif; font-weight: normal}
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ul.no-bullet {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<a name="Environment"></a>
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<div class="header">
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<p>
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Next: <a href="Working-Directory.html#Working-Directory" accesskey="n" rel="next">Working Directory</a>, Previous: <a href="Arguments.html#Arguments" accesskey="p" rel="prev">Arguments</a>, Up: <a href="Running.html#Running" accesskey="u" rel="up">Running</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Your-Program_0027s-Environment"></a>
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<h3 class="section">4.4 Your Program’s Environment</h3>
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<a name="index-environment-_0028of-your-program_0029"></a>
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<p>The <em>environment</em> consists of a set of environment variables and
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their values. Environment variables conventionally record such things as
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your user name, your home directory, your terminal type, and your search
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path for programs to run. Usually you set up environment variables with
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the shell and they are inherited by all the other programs you run. When
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debugging, it can be useful to try running your program with a modified
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environment without having to start <small>GDB</small> over again.
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</p>
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<dl compact="compact">
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<dd><a name="index-path"></a>
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</dd>
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<dt><code>path <var>directory</var></code></dt>
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<dd><p>Add <var>directory</var> to the front of the <code>PATH</code> environment variable
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(the search path for executables) that will be passed to your program.
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The value of <code>PATH</code> used by <small>GDB</small> does not change.
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You may specify several directory names, separated by whitespace or by a
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system-dependent separator character (‘<samp>:</samp>’ on Unix, ‘<samp>;</samp>’ on
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MS-DOS and MS-Windows). If <var>directory</var> is already in the path, it
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is moved to the front, so it is searched sooner.
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</p>
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<p>You can use the string ‘<samp>$cwd</samp>’ to refer to whatever is the current
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working directory at the time <small>GDB</small> searches the path. If you
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use ‘<samp>.</samp>’ instead, it refers to the directory where you executed the
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<code>path</code> command. <small>GDB</small> replaces ‘<samp>.</samp>’ in the
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<var>directory</var> argument (with the current path) before adding
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<var>directory</var> to the search path.
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</p>
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<a name="index-show-paths"></a>
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</dd>
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<dt><code>show paths</code></dt>
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<dd><p>Display the list of search paths for executables (the <code>PATH</code>
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environment variable).
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</p>
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<a name="index-show-environment"></a>
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</dd>
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<dt><code>show environment <span class="roman">[</span><var>varname</var><span class="roman">]</span></code></dt>
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<dd><p>Print the value of environment variable <var>varname</var> to be given to
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your program when it starts. If you do not supply <var>varname</var>,
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print the names and values of all environment variables to be given to
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your program. You can abbreviate <code>environment</code> as <code>env</code>.
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</p>
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<a name="index-set-environment"></a>
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<a name="set-environment"></a></dd>
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<dt><code>set environment <var>varname</var> <span class="roman">[</span>=<var>value</var><span class="roman">]</span></code></dt>
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<dd><p>Set environment variable <var>varname</var> to <var>value</var>. The value
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changes for your program (and the shell <small>GDB</small> uses to launch
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it), not for <small>GDB</small> itself. The <var>value</var> may be any string; the
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values of environment variables are just strings, and any
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interpretation is supplied by your program itself. The <var>value</var>
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parameter is optional; if it is eliminated, the variable is set to a
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null value.
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</p>
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<p>For example, this command:
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</p>
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<div class="smallexample">
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<pre class="smallexample">set env USER = foo
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</pre></div>
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<p>tells the debugged program, when subsequently run, that its user is named
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‘<samp>foo</samp>’. (The spaces around ‘<samp>=</samp>’ are used for clarity here; they
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are not actually required.)
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</p>
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<p>Note that on Unix systems, <small>GDB</small> runs your program via a shell,
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which also inherits the environment set with <code>set environment</code>.
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If necessary, you can avoid that by using the ‘<samp>env</samp>’ program as a
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wrapper instead of using <code>set environment</code>. See <a href="Starting.html#set-exec_002dwrapper">set exec-wrapper</a>, for an example doing just that.
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</p>
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<p>Environment variables that are set by the user are also transmitted to
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<code>gdbserver</code> to be used when starting the remote inferior.
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see <a href="General-Query-Packets.html#QEnvironmentHexEncoded">QEnvironmentHexEncoded</a>.
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</p>
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<a name="index-unset-environment"></a>
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<a name="unset-environment"></a></dd>
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<dt><code>unset environment <var>varname</var></code></dt>
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<dd><p>Remove variable <var>varname</var> from the environment to be passed to your
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program. This is different from ‘<samp>set env <var>varname</var> =</samp>’;
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<code>unset environment</code> removes the variable from the environment,
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rather than assigning it an empty value.
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</p>
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<p>Environment variables that are unset by the user are also unset on
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<code>gdbserver</code> when starting the remote inferior.
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see <a href="General-Query-Packets.html#QEnvironmentUnset">QEnvironmentUnset</a>.
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</p></dd>
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</dl>
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<p><em>Warning:</em> On Unix systems, <small>GDB</small> runs your program using
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the shell indicated by your <code>SHELL</code> environment variable if it
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exists (or <code>/bin/sh</code> if not). If your <code>SHELL</code> variable
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names a shell that runs an initialization file when started
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non-interactively—such as <samp>.cshrc</samp> for C-shell, $<samp>.zshenv</samp>
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for the Z shell, or the file specified in the ‘<samp>BASH_ENV</samp>’
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environment variable for BASH—any variables you set in that file
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affect your program. You may wish to move setting of environment
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variables to files that are only run when you sign on, such as
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<samp>.login</samp> or <samp>.profile</samp>.
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</p>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Working-Directory.html#Working-Directory" accesskey="n" rel="next">Working Directory</a>, Previous: <a href="Arguments.html#Arguments" accesskey="p" rel="prev">Arguments</a>, Up: <a href="Running.html#Running" accesskey="u" rel="up">Running</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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