136 lines
5.4 KiB
HTML
136 lines
5.4 KiB
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<html lang="en">
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<head>
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<title>open - Debugging with GDB</title>
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<meta name="description" content="Debugging with GDB">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="List-of-Supported-Calls.html#List-of-Supported-Calls" title="List of Supported Calls">
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<link rel="next" href="close.html#close" title="close">
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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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</head>
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<body>
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<div class="node">
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<a name="open"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="close.html#close">close</a>,
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Up: <a rel="up" accesskey="u" href="List-of-Supported-Calls.html#List-of-Supported-Calls">List of Supported Calls</a>
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<hr>
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</div>
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<h5 class="unnumberedsubsubsec">open</h5>
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<p><a name="index-open_002c-file_002di_002fo-system-call-3604"></a>
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<dl>
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<dt>Synopsis:<dd>
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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>
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<br><dt>Request:<dd>‘<samp><span class="samp">Fopen,</span><var>pathptr</var><span class="samp">/</span><var>len</var><span class="samp">,</span><var>flags</var><span class="samp">,</span><var>mode</var></samp>’
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<p class="noindent"><var>flags</var> is the bitwise <code>OR</code> of the following values:
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<dl>
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<dt><code>O_CREAT</code><dd>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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<br><dt><code>O_EXCL</code><dd>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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<br><dt><code>O_TRUNC</code><dd>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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<br><dt><code>O_APPEND</code><dd>The file is opened in append mode.
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<br><dt><code>O_RDONLY</code><dd>The file is opened for reading only.
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<br><dt><code>O_WRONLY</code><dd>The file is opened for writing only.
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<br><dt><code>O_RDWR</code><dd>The file is opened for reading and writing.
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</dl>
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<p class="noindent">Other bits are silently ignored.
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<p class="noindent"><var>mode</var> is the bitwise <code>OR</code> of the following values:
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<dl>
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<dt><code>S_IRUSR</code><dd>User has read permission.
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<br><dt><code>S_IWUSR</code><dd>User has write permission.
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<br><dt><code>S_IRGRP</code><dd>Group has read permission.
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<br><dt><code>S_IWGRP</code><dd>Group has write permission.
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<br><dt><code>S_IROTH</code><dd>Others have read permission.
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<br><dt><code>S_IWOTH</code><dd>Others have write permission.
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</dl>
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<p class="noindent">Other bits are silently ignored.
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<br><dt>Return value:<dd><code>open</code> returns the new file descriptor or -1 if an error
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occurred.
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<br><dt>Errors:<dd>
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<dl>
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<dt><code>EEXIST</code><dd><var>pathname</var> already exists and <code>O_CREAT</code> and <code>O_EXCL</code> were used.
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<br><dt><code>EISDIR</code><dd><var>pathname</var> refers to a directory.
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<br><dt><code>EACCES</code><dd>The requested access is not allowed.
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<br><dt><code>ENAMETOOLONG</code><dd><var>pathname</var> was too long.
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<br><dt><code>ENOENT</code><dd>A directory component in <var>pathname</var> does not exist.
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<br><dt><code>ENODEV</code><dd><var>pathname</var> refers to a device, pipe, named pipe or socket.
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<br><dt><code>EROFS</code><dd><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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<br><dt><code>EFAULT</code><dd><var>pathname</var> is an invalid pointer value.
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<br><dt><code>ENOSPC</code><dd>No space on device to create the file.
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<br><dt><code>EMFILE</code><dd>The process already has the maximum number of files open.
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<br><dt><code>ENFILE</code><dd>The limit on the total number of files open on the system
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has been reached.
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<br><dt><code>EINTR</code><dd>The call was interrupted by the user.
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</dl>
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</dl>
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</body></html>
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