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| <h3 class="section">4.4 Your Program's Environment</h3> |
| |
| <p><a name="index-environment-_0028of-your-program_0029-129"></a>The <dfn>environment</dfn> consists of a set of environment variables and |
| their values. Environment variables conventionally record such things as |
| your user name, your home directory, your terminal type, and your search |
| path for programs to run. Usually you set up environment variables with |
| the shell and they are inherited by all the other programs you run. When |
| debugging, it can be useful to try running your program with a modified |
| environment without having to start <span class="sc">gdb</span> over again. |
| |
| |
| <a name="index-path-130"></a> |
| <dl><dt><code>path </code><var>directory</var><dd>Add <var>directory</var> to the front of the <code>PATH</code> environment variable |
| (the search path for executables) that will be passed to your program. |
| The value of <code>PATH</code> used by <span class="sc">gdb</span> does not change. |
| You may specify several directory names, separated by whitespace or by a |
| system-dependent separator character (‘<samp><span class="samp">:</span></samp>’ on Unix, ‘<samp><span class="samp">;</span></samp>’ on |
| MS-DOS and MS-Windows). If <var>directory</var> is already in the path, it |
| is moved to the front, so it is searched sooner. |
| |
| <p>You can use the string ‘<samp><span class="samp">$cwd</span></samp>’ to refer to whatever is the current |
| working directory at the time <span class="sc">gdb</span> searches the path. If you |
| use ‘<samp><span class="samp">.</span></samp>’ instead, it refers to the directory where you executed the |
| <code>path</code> command. <span class="sc">gdb</span> replaces ‘<samp><span class="samp">.</span></samp>’ in the |
| <var>directory</var> argument (with the current path) before adding |
| <var>directory</var> to the search path. |
| <!-- 'path' is explicitly nonrepeatable, but RMS points out it is silly to --> |
| <!-- document that, since repeating it would be a no-op. --> |
| |
| <p><a name="index-show-paths-131"></a><br><dt><code>show paths</code><dd>Display the list of search paths for executables (the <code>PATH</code> |
| environment variable). |
| |
| <p><a name="index-show-environment-132"></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 |
| your program when it starts. If you do not supply <var>varname</var>, |
| print the names and values of all environment variables to be given to |
| your program. You can abbreviate <code>environment</code> as <code>env</code>. |
| |
| <p><a name="index-set-environment-133"></a><a name="set-environment"></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 |
| changes for your program (and the shell <span class="sc">gdb</span> uses to launch |
| it), not for <span class="sc">gdb</span> itself. The <var>value</var> may be any string; the |
| values of environment variables are just strings, and any |
| interpretation is supplied by your program itself. The <var>value</var> |
| parameter is optional; if it is eliminated, the variable is set to a |
| null value. |
| <!-- "any string" here does not include leading, trailing --> |
| <!-- blanks. Gnu asks: does anyone care? --> |
| |
| <p>For example, this command: |
| |
| <pre class="smallexample"> set env USER = foo |
| </pre> |
| <p class="noindent">tells the debugged program, when subsequently run, that its user is named |
| ‘<samp><span class="samp">foo</span></samp>’. (The spaces around ‘<samp><span class="samp">=</span></samp>’ are used for clarity here; they |
| are not actually required.) |
| |
| <p>Note that on Unix systems, <span class="sc">gdb</span> runs your program via a shell, |
| which also inherits the environment set with <code>set environment</code>. |
| If necessary, you can avoid that by using the ‘<samp><span class="samp">env</span></samp>’ program as a |
| wrapper instead of using <code>set environment</code>. See <a href="set-exec_002dwrapper.html#set-exec_002dwrapper">set exec-wrapper</a>, for an example doing just that. |
| |
| <p>Environment variables that are set by the user are also transmitted to |
| <samp><span class="command">gdbserver</span></samp> to be used when starting the remote inferior. |
| see <a href="QEnvironmentHexEncoded.html#QEnvironmentHexEncoded">QEnvironmentHexEncoded</a>. |
| |
| <p><a name="index-unset-environment-134"></a><a name="unset-environment"></a><br><dt><code>unset environment </code><var>varname</var><dd>Remove variable <var>varname</var> from the environment to be passed to your |
| program. This is different from ‘<samp><span class="samp">set env </span><var>varname</var><span class="samp"> =</span></samp>’; |
| <code>unset environment</code> removes the variable from the environment, |
| rather than assigning it an empty value. |
| |
| <p>Environment variables that are unset by the user are also unset on |
| <samp><span class="command">gdbserver</span></samp> when starting the remote inferior. |
| see <a href="QEnvironmentUnset.html#QEnvironmentUnset">QEnvironmentUnset</a>. |
| </dl> |
| |
| <p><em>Warning:</em> On Unix systems, <span class="sc">gdb</span> runs your program using |
| the shell indicated by your <code>SHELL</code> environment variable if it |
| exists (or <code>/bin/sh</code> if not). If your <code>SHELL</code> variable |
| names a shell that runs an initialization file when started |
| non-interactively—such as <samp><span class="file">.cshrc</span></samp> for C-shell, $<samp><span class="file">.zshenv</span></samp> |
| for the Z shell, or the file specified in the ‘<samp><span class="samp">BASH_ENV</span></samp>’ |
| environment variable for BASH—any variables you set in that file |
| affect your program. You may wish to move setting of environment |
| variables to files that are only run when you sign on, such as |
| <samp><span class="file">.login</span></samp> or <samp><span class="file">.profile</span></samp>. |
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