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| <a name="Patching-Programs"></a> |
| <h3 class="section">17.6 Patching Programs</h3> |
| |
| <a name="index-patching-binaries"></a> |
| <a name="index-writing-into-executables"></a> |
| <a name="index-writing-into-corefiles"></a> |
| |
| <p>By default, <small>GDB</small> opens the file containing your program’s |
| executable code (or the corefile) read-only. This prevents accidental |
| alterations to machine code; but it also prevents you from intentionally |
| patching your program’s binary. |
| </p> |
| <p>If you’d like to be able to patch the binary, you can specify that |
| explicitly with the <code>set write</code> command. For example, you might |
| want to turn on internal debugging flags, or even to make emergency |
| repairs. |
| </p> |
| <dl compact="compact"> |
| <dd><a name="index-set-write"></a> |
| </dd> |
| <dt><code>set write on</code></dt> |
| <dt><code>set write off</code></dt> |
| <dd><p>If you specify ‘<samp>set write on</samp>’, <small>GDB</small> opens executable and |
| core files for both reading and writing; if you specify <kbd>set write |
| off</kbd> (the default), <small>GDB</small> opens them read-only. |
| </p> |
| <p>If you have already loaded a file, you must load it again (using the |
| <code>exec-file</code> or <code>core-file</code> command) after changing <code>set |
| write</code>, for your new setting to take effect. |
| </p> |
| </dd> |
| <dt><code>show write</code></dt> |
| <dd><a name="index-show-write"></a> |
| <p>Display whether executable files and core files are opened for writing |
| as well as reading. |
| </p></dd> |
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