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<title>Debugging with GDB: open</title>
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<a name="open"></a>
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<div class="header">
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<p>
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Next: <a href="close.html#close" accesskey="n" rel="next">close</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</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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<hr>
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<a name="open-1"></a>
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<h4 class="unnumberedsubsubsec">open</h4>
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<a name="index-open_002c-file_002di_002fo-system-call"></a>
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<dl compact="compact">
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<dt>Synopsis:</dt>
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<dd><div class="smallexample">
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<pre class="smallexample">int open(const char *pathname, int flags);
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int open(const char *pathname, int flags, mode_t mode);
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</pre></div>
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</dd>
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<dt>Request:</dt>
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<dd><p>‘<samp>Fopen,<var>pathptr</var>/<var>len</var>,<var>flags</var>,<var>mode</var></samp>’
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</p>
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<p><var>flags</var> is the bitwise <code>OR</code> of the following values:
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</p>
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<dl compact="compact">
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<dt><code>O_CREAT</code></dt>
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<dd><p>If the file does not exist it will be created. The host
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rules apply as far as file ownership and time stamps
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are concerned.
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</p>
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</dd>
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<dt><code>O_EXCL</code></dt>
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<dd><p>When used with <code>O_CREAT</code>, if the file already exists it is
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an error and open() fails.
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</p>
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</dd>
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<dt><code>O_TRUNC</code></dt>
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<dd><p>If the file already exists and the open mode allows
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writing (<code>O_RDWR</code> or <code>O_WRONLY</code> is given) it will be
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truncated to zero length.
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</p>
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</dd>
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<dt><code>O_APPEND</code></dt>
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<dd><p>The file is opened in append mode.
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</p>
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</dd>
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<dt><code>O_RDONLY</code></dt>
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<dd><p>The file is opened for reading only.
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</p>
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</dd>
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<dt><code>O_WRONLY</code></dt>
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<dd><p>The file is opened for writing only.
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</p>
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</dd>
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<dt><code>O_RDWR</code></dt>
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<dd><p>The file is opened for reading and writing.
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</p></dd>
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</dl>
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<p>Other bits are silently ignored.
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</p>
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<p><var>mode</var> is the bitwise <code>OR</code> of the following values:
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</p>
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<dl compact="compact">
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<dt><code>S_IRUSR</code></dt>
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<dd><p>User has read permission.
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</p>
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</dd>
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<dt><code>S_IWUSR</code></dt>
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<dd><p>User has write permission.
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</p>
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</dd>
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<dt><code>S_IRGRP</code></dt>
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<dd><p>Group has read permission.
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</p>
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</dd>
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<dt><code>S_IWGRP</code></dt>
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<dd><p>Group has write permission.
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</p>
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</dd>
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<dt><code>S_IROTH</code></dt>
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<dd><p>Others have read permission.
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</p>
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</dd>
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<dt><code>S_IWOTH</code></dt>
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<dd><p>Others have write permission.
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</p></dd>
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</dl>
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<p>Other bits are silently ignored.
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</p>
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</dd>
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<dt>Return value:</dt>
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<dd><p><code>open</code> returns the new file descriptor or -1 if an error
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occurred.
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</p>
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</dd>
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<dt>Errors:</dt>
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<dd>
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<dl compact="compact">
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<dt><code>EEXIST</code></dt>
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<dd><p><var>pathname</var> already exists and <code>O_CREAT</code> and <code>O_EXCL</code> were used.
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</p>
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</dd>
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<dt><code>EISDIR</code></dt>
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<dd><p><var>pathname</var> refers to a directory.
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</p>
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</dd>
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<dt><code>EACCES</code></dt>
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<dd><p>The requested access is not allowed.
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</p>
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</dd>
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<dt><code>ENAMETOOLONG</code></dt>
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<dd><p><var>pathname</var> was too long.
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</p>
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</dd>
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<dt><code>ENOENT</code></dt>
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<dd><p>A directory component in <var>pathname</var> does not exist.
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</p>
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</dd>
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<dt><code>ENODEV</code></dt>
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<dd><p><var>pathname</var> refers to a device, pipe, named pipe or socket.
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</p>
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</dd>
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<dt><code>EROFS</code></dt>
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<dd><p><var>pathname</var> refers to a file on a read-only filesystem and
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write access was requested.
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</p>
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</dd>
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<dt><code>EFAULT</code></dt>
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<dd><p><var>pathname</var> is an invalid pointer value.
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</p>
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</dd>
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<dt><code>ENOSPC</code></dt>
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<dd><p>No space on device to create the file.
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</p>
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</dd>
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<dt><code>EMFILE</code></dt>
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<dd><p>The process already has the maximum number of files open.
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</p>
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</dd>
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<dt><code>ENFILE</code></dt>
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<dd><p>The limit on the total number of files open on the system
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has been reached.
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</p>
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</dd>
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<dt><code>EINTR</code></dt>
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<dd><p>The call was interrupted by the user.
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</p></dd>
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</dl>
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</dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="close.html#close" accesskey="n" rel="next">close</a>, Up: <a href="List-of-Supported-Calls.html#List-of-Supported-Calls" accesskey="u" rel="up">List of Supported Calls</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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