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<h4 class="subsection">2.1.1 Choosing Files</h4>

<p>When <span class="sc">gdb</span> starts, it reads any arguments other than options as
specifying an executable file and core file (or process ID).  This is
the same as if the arguments were specified by the &lsquo;<samp><span class="samp">-se</span></samp>&rsquo; and
&lsquo;<samp><span class="samp">-c</span></samp>&rsquo; (or &lsquo;<samp><span class="samp">-p</span></samp>&rsquo;) options respectively.  (<span class="sc">gdb</span> reads the
first argument that does not have an associated option flag as
equivalent to the &lsquo;<samp><span class="samp">-se</span></samp>&rsquo; option followed by that argument; and the
second argument that does not have an associated option flag, if any, as
equivalent to the &lsquo;<samp><span class="samp">-c</span></samp>&rsquo;/&lsquo;<samp><span class="samp">-p</span></samp>&rsquo; option followed by that argument.) 
If the second argument begins with a decimal digit, <span class="sc">gdb</span> will
first attempt to attach to it as a process, and if that fails, attempt
to open it as a corefile.  If you have a corefile whose name begins with
a digit, you can prevent <span class="sc">gdb</span> from treating it as a pid by
prefixing it with <samp><span class="file">./</span></samp>, e.g. <samp><span class="file">./12345</span></samp>.

   <p>If <span class="sc">gdb</span> has not been configured to included core file support,
such as for most embedded targets, then it will complain about a second
argument and ignore it.

   <p>Many options have both long and short forms; both are shown in the
following list.  <span class="sc">gdb</span> also recognizes the long forms if you truncate
them, so long as enough of the option is present to be unambiguous. 
(If you prefer, you can flag option arguments with &lsquo;<samp><span class="samp">--</span></samp>&rsquo; rather
than &lsquo;<samp><span class="samp">-</span></samp>&rsquo;, though we illustrate the more usual convention.)

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     <dl>
<dt><code>-symbols </code><var>file</var><dt><code>-s </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dsymbols_007d-4"></a><a name="index-g_t_0040code_007b_002ds_007d-5"></a>Read symbol table from file <var>file</var>.

     <br><dt><code>-exec </code><var>file</var><dt><code>-e </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dexec_007d-6"></a><a name="index-g_t_0040code_007b_002de_007d-7"></a>Use file <var>file</var> as the executable file to execute when appropriate,
and for examining pure data in conjunction with a core dump.

     <br><dt><code>-se </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dse_007d-8"></a>Read symbol table from file <var>file</var> and use it as the executable
file.

     <br><dt><code>-core </code><var>file</var><dt><code>-c </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dcore_007d-9"></a><a name="index-g_t_0040code_007b_002dc_007d-10"></a>Use file <var>file</var> as a core dump to examine.

     <br><dt><code>-pid </code><var>number</var><dt><code>-p </code><var>number</var><dd><a name="index-g_t_0040code_007b_002d_002dpid_007d-11"></a><a name="index-g_t_0040code_007b_002dp_007d-12"></a>Connect to process ID <var>number</var>, as with the <code>attach</code> command.

     <br><dt><code>-command </code><var>file</var><dt><code>-x </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dcommand_007d-13"></a><a name="index-g_t_0040code_007b_002dx_007d-14"></a>Execute commands from file <var>file</var>.  The contents of this file is
evaluated exactly as the <code>source</code> command would. 
See <a href="Command-Files.html#Command-Files">Command files</a>.

     <br><dt><code>-eval-command </code><var>command</var><dt><code>-ex </code><var>command</var><dd><a name="index-g_t_0040code_007b_002d_002deval_002dcommand_007d-15"></a><a name="index-g_t_0040code_007b_002dex_007d-16"></a>Execute a single <span class="sc">gdb</span> command.

     <p>This option may be used multiple times to call multiple commands.  It may
also be interleaved with &lsquo;<samp><span class="samp">-command</span></samp>&rsquo; as required.

     <pre class="smallexample">          gdb -ex 'target sim' -ex 'load' \
             -x setbreakpoints -ex 'run' a.out
</pre>
     <br><dt><code>-init-command </code><var>file</var><dt><code>-ix </code><var>file</var><dd><a name="index-g_t_0040code_007b_002d_002dinit_002dcommand_007d-17"></a><a name="index-g_t_0040code_007b_002dix_007d-18"></a>Execute commands from file <var>file</var> before loading the inferior (but
after loading gdbinit files). 
See <a href="Startup.html#Startup">Startup</a>.

     <br><dt><code>-init-eval-command </code><var>command</var><dt><code>-iex </code><var>command</var><dd><a name="index-g_t_0040code_007b_002d_002dinit_002deval_002dcommand_007d-19"></a><a name="index-g_t_0040code_007b_002diex_007d-20"></a>Execute a single <span class="sc">gdb</span> command before loading the inferior (but
after loading gdbinit files). 
See <a href="Startup.html#Startup">Startup</a>.

     <br><dt><code>-directory </code><var>directory</var><dt><code>-d </code><var>directory</var><dd><a name="index-g_t_0040code_007b_002d_002ddirectory_007d-21"></a><a name="index-g_t_0040code_007b_002dd_007d-22"></a>Add <var>directory</var> to the path to search for source and script files.

     <br><dt><code>-r</code><dt><code>-readnow</code><dd><a name="index-g_t_0040code_007b_002d_002dreadnow_007d-23"></a><a name="index-g_t_0040code_007b_002dr_007d-24"></a>Read each symbol file's entire symbol table immediately, rather than
the default, which is to read it incrementally as it is needed. 
This makes startup slower, but makes future operations faster.

     <br><dt><code>--readnever</code><dd><a name="g_t_002d_002dreadnever"></a><a name="index-g_t_0040code_007b_002d_002dreadnever_007d_002c-command_002dline-option-25"></a>Do not read each symbol file's symbolic debug information.  This makes
startup faster but at the expense of not being able to perform
symbolic debugging.  DWARF unwind information is also not read,
meaning backtraces may become incomplete or inaccurate.  One use of
this is when a user simply wants to do the following sequence: attach,
dump core, detach.  Loading the debugging information in this case is
an unnecessary cause of delay. 
</dl>

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