189 lines
6.8 KiB
HTML
189 lines
6.8 KiB
HTML
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<title>fchmod</title>
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<basefont size="3"> <a name="fchmod"></a> <a name="tag_03_138"></a><!-- fchmod -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_03_138_01"></a>NAME</h4>
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<blockquote>fchmod - change mode of a file</blockquote>
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<h4><a name="tag_03_138_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<p><code><tt>#include <<a href="../basedefs/sys/stat.h.html">sys/stat.h</a>><br>
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<br>
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int fchmod(int</tt> <i>fildes</i><tt>, mode_t</tt> <i>mode</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_138_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>fchmod</i>() function shall be equivalent to <a href="../functions/chmod.html"><i>chmod</i>()</a> except that the file
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whose permissions are changed is specified by the file descriptor <i>fildes</i>.</p>
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<p><sup>[<a href="javascript:open_code('SHM')">SHM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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If <i>fildes</i> references a shared memory object, the <i>fchmod</i>() function need only affect the S_IRUSR, S_IWUSR, S_IRGRP,
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S_IWGRP, S_IROTH, and S_IWOTH file permission bits. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
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<p><sup>[<a href="javascript:open_code('TYM')">TYM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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If <i>fildes</i> references a typed memory object, the behavior of <i>fchmod</i>() is unspecified. <img src="../images/opt-end.gif"
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alt="[Option End]" border="0"></p>
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<p>If <i>fildes</i> refers to a socket, the behavior of <i>fchmod</i>() is unspecified.</p>
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<p><sup>[<a href="javascript:open_code('XSR')">XSR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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If <i>fildes</i> refers to a STREAM (which is <a href="../functions/fattach.html"><i>fattach</i>()</a>-ed into the file system name
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space) the call returns successfully, doing nothing. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></p>
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</blockquote>
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<h4><a name="tag_03_138_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, <i>fchmod</i>() shall return 0. Otherwise, it shall return -1 and set <i>errno</i> to indicate the
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error.</p>
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</blockquote>
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<h4><a name="tag_03_138_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>fchmod</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EBADF]</dt>
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<dd>The <i>fildes</i> argument is not an open file descriptor.</dd>
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<dt>[EPERM]</dt>
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<dd>The effective user ID does not match the owner of the file and the process does not have appropriate privilege.</dd>
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<dt>[EROFS]</dt>
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<dd>The file referred to by <i>fildes</i> resides on a read-only file system.</dd>
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</dl>
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<p>The <i>fchmod</i>() function may fail if:</p>
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<dl compact>
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<dt>[EINTR]</dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The <i>fchmod</i>() function was interrupted by a signal. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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<dt>[EINVAL]</dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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The value of the <i>mode</i> argument is invalid. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
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<dt>[EINVAL]</dt>
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<dd>The <i>fildes</i> argument refers to a pipe and the implementation disallows execution of <i>fchmod</i>() on a pipe.</dd>
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</dl>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_03_138_06"></a>EXAMPLES</h4>
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<blockquote>
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<h5><a name="tag_03_138_06_01"></a>Changing the Current Permissions for a File</h5>
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<p>The following example shows how to change the permissions for a file named <b>/home/cnd/mod1</b> so that the owner and group
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have read/write/execute permissions, but the world only has read/write permissions.</p>
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<pre>
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<tt>#include <sys/stat.h>
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#include <fcntl.h>
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<br>
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mode_t mode;
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int fildes;
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...
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fildes = open("/home/cnd/mod1", O_RDWR);
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fchmod(fildes, S_IRWXU | S_IRWXG | S_IROTH | S_IWOTH);
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_138_07"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_138_08"></a>RATIONALE</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_138_09"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_03_138_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="chmod.html"><i>chmod</i>()</a> , <a href="chown.html"><i>chown</i>()</a> , <a href="creat.html"><i>creat</i>()</a> , <a
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href="fcntl.html"><i>fcntl</i>()</a> , <a href="fstatvfs.html"><i>fstatvfs</i>()</a> , <a href="mknod.html"><i>mknod</i>()</a> , <a
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href="open.html"><i>open</i>()</a> , <a href="read.html"><i>read</i>()</a> , <a href="stat.html"><i>stat</i>()</a> , <a href=
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"write.html"><i>write</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_138_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4, Version 2.</p>
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</blockquote>
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<h4><a name="tag_03_138_12"></a>Issue 5</h4>
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<blockquote>
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<p>Moved from X/OPEN UNIX extension to BASE and aligned with <i>fchmod</i>() in the POSIX Realtime Extension. Specifically, the
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second paragraph of the DESCRIPTION is added and a second instance of [EINVAL] is defined in the list of optional errors.</p>
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</blockquote>
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<h4><a name="tag_03_138_13"></a>Issue 6</h4>
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<blockquote>
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<p>The DESCRIPTION is updated for alignment with IEEE Std 1003.1j-2000 by stating that <i>fchmod</i>() behavior is
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unspecified for typed memory objects.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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