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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>mknod</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="mknod"></a> <a name="tag_03_373"></a><!-- mknod --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_373_01"></a>NAME</h4><blockquote>mknod - make a directory, a special file, or a regular file</blockquote><h4><a name="tag_03_373_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><div class="box"><code><tt><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> #include <<a href="../basedefs/sys/stat.h.html">sys/stat.h</a>><br><br> int mknod(const char *</tt><i>path</i><tt>, mode_t</tt> <i>mode</i><tt>, dev_t</tt> <i>dev</i><tt>); <img src="../images/opt-end.gif" alt="[Option End]" border="0"></tt></code></div><tt><br></tt></blockquote><h4><a name="tag_03_373_03"></a>DESCRIPTION</h4><blockquote><p>The <i>mknod</i>() function shall create a new file named by the pathname to which the argument <i>path</i> points.</p><p>The file type for <i>path</i> is OR'ed into the <i>mode</i> argument, and the application shall select one of the followingsymbolic constants:</p><center><table border="1" cellpadding="3" align="center"><tr valign="top"><th align="center"><p class="tent"><b>Name</b></p></th><th align="center"><p class="tent"><b>Description</b></p></th></tr><tr valign="top"><td align="left"><p class="tent">S_IFIFO</p></td><td align="left"><p class="tent">FIFO-special</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IFCHR</p></td><td align="left"><p class="tent">Character-special (non-portable)</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IFDIR</p></td><td align="left"><p class="tent">Directory (non-portable)</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IFBLK</p></td><td align="left"><p class="tent">Block-special (non-portable)</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IFREG</p></td><td align="left"><p class="tent">Regular (non-portable)</p></td></tr></table></center><p>The only portable use of <i>mknod</i>() is to create a FIFO-special file. If <i>mode</i> is not S_IFIFO or <i>dev</i> is not 0,the behavior of <i>mknod</i>() is unspecified.</p><p>The permissions for the new file are OR'ed into the <i>mode</i> argument, and may be selected from any combination of thefollowing symbolic constants:</p><center><table border="1" cellpadding="3" align="center"><tr valign="top"><th align="center"><p class="tent"><b>Name</b></p></th><th align="center"><p class="tent"><b>Description</b></p></th></tr><tr valign="top"><td align="left"><p class="tent">S_ISUID</p></td><td align="left"><p class="tent">Set user ID on execution.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_ISGID</p></td><td align="left"><p class="tent">Set group ID on execution.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IRWXU</p></td><td align="left"><p class="tent">Read, write, or execute (search) by owner.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IRUSR</p></td><td align="left"><p class="tent">Read by owner.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IWUSR</p></td><td align="left"><p class="tent">Write by owner.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IXUSR</p></td><td align="left"><p class="tent">Execute (search) by owner.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IRWXG</p></td><td align="left"><p class="tent">Read, write, or execute (search) by group.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IRGRP</p></td><td align="left"><p class="tent">Read by group.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IWGRP</p></td><td align="left"><p class="tent">Write by group.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IXGRP</p></td><td align="left"><p class="tent">Execute (search) by group.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IRWXO</p></td><td align="left"><p class="tent">Read, write, or execute (search) by others.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IROTH</p></td><td align="left"><p class="tent">Read by others.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IWOTH</p></td><td align="left"><p class="tent">Write by others.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_IXOTH</p></td><td align="left"><p class="tent">Execute (search) by others.</p></td></tr><tr valign="top"><td align="left"><p class="tent">S_ISVTX</p></td><td align="left"><p class="tent">On directories, restricted deletion flag.</p></td></tr></table></center><p>The user ID of the file shall be initialized to the effective user ID of the process. The group ID of the file shall beinitialized to either the effective group ID of the process or the group ID of the parent directory. Implementations shall providea way to initialize the file's group ID to the group ID of the parent directory. Implementations may, but need not, provide animplementation-defined way to initialize the file's group ID to the effective group ID of the calling process. The owner, group,and other permission bits of <i>mode</i> shall be modified by the file mode creation mask of the process. The <i>mknod</i>()function shall clear each bit whose corresponding bit in the file mode creation mask of the process is set.</p><p>If <i>path</i> names a symbolic link, <i>mknod</i>() shall fail and set <i>errno</i> to [EEXIST].</p><p>Upon successful completion, <i>mknod</i>() shall mark for update the <i>st_atime</i>, <i>st_ctime</i>, and <i>st_mtime</i>fields of the file. Also, the <i>st_ctime</i> and <i>st_mtime</i> fields of the directory that contains the new entry shall bemarked for update.</p><p>Only a process with appropriate privileges may invoke <i>mknod</i>() for file types other than FIFO-special.</p></blockquote><h4><a name="tag_03_373_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, <i>mknod</i>() shall return 0. Otherwise, it shall return -1, the new file shall not be created, and<i>errno</i> shall be set to indicate the error.</p></blockquote><h4><a name="tag_03_373_05"></a>ERRORS</h4><blockquote><p>The <i>mknod</i>() function shall fail if:</p><dl compact><dt>[EACCES]</dt><dd>A component of the path prefix denies search permission, or write permission is denied on the parent directory.</dd><dt>[EEXIST]</dt><dd>The named file exists.</dd><dt>[EINVAL]</dt><dd>An invalid argument exists.</dd><dt>[EIO]</dt><dd>An I/O error occurred while accessing the file system.</dd><dt>[ELOOP]</dt><dd>A loop exists in symbolic links encountered during resolution of the <i>path</i> argument.</dd><dt>[ENAMETOOLONG]</dt><dd>The length of a pathname exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.</dd><dt>[ENOENT]</dt><dd>A component of the path prefix specified by <i>path</i> does not name an existing directory or <i>path</i> is an emptystring.</dd><dt>[ENOSPC]</dt><dd>The directory that would contain the new file cannot be extended or the file system is out of file allocation resources.</dd><dt>[ENOTDIR]</dt><dd>A component of the path prefix is not a directory.</dd><dt>[EPERM]</dt><dd>The invoking process does not have appropriate privileges and the file type is not FIFO-special.</dd><dt>[EROFS]</dt><dd>The directory in which the file is to be created is located on a read-only file system.</dd></dl><p>The <i>mknod</i>() function may fail if:</p><dl compact><dt>[ELOOP]</dt><dd>More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the <i>path</i> argument.</dd><dt>[ENAMETOOLONG]</dt><dd>Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_373_06"></a>EXAMPLES</h4><blockquote><h5><a name="tag_03_373_06_01"></a>Creating a FIFO Special File</h5><p>The following example shows how to create a FIFO special file named <b>/home/cnd/mod_done</b>, with read/write permissions forowner, and with read permissions for group and others.</p><pre><tt>#include <sys/types.h>#include <sys/stat.h><br>dev_t dev;int status;...status = mknod("/home/cnd/mod_done", S_IFIFO | S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH, dev);</tt></pre></blockquote><h4><a name="tag_03_373_07"></a>APPLICATION USAGE</h4><blockquote><p>The <a href="../functions/mkfifo.html"><i>mkfifo</i>()</a> function is preferred over this function for making FIFO specialfiles.</p></blockquote><h4><a name="tag_03_373_08"></a>RATIONALE</h4><blockquote><p>The POSIX.1-1990 standard required that the group ID of a newly created file be set to the group ID of its parent directory orto the effective group ID of the creating process. FIPS 151-2 required that implementations provide a way to have the group ID beset to the group ID of the containing directory, but did not prohibit implementations also supporting a way to set the group ID tothe effective group ID of the creating process. Conforming applications should not assume which group ID will be used. If itmatters, an application can use <a href="../functions/chown.html"><i>chown</i>()</a> to set the group ID after the file is created,or determine under what conditions the implementation will set the desired group ID.</p></blockquote><h4><a name="tag_03_373_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_373_10"></a>SEE ALSO</h4><blockquote><p><a href="chmod.html"><i>chmod</i>()</a> , <a href="creat.html"><i>creat</i>()</a> , <a href="exec.html"><i><a href="../functions/exec.html">exec</a></i>()</a> , <a href="mkdir.html"><i>mkdir</i>()</a> , <a href="mkfifo.html"><i>mkfifo</i>()</a> ,<a href="open.html"><i>open</i>()</a> , <a href="stat.html"><i>stat</i>()</a> , <a href="umask.html"><i>umask</i>()</a> , the BaseDefinitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a></p></blockquote><h4><a name="tag_03_373_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 4, Version 2.</p></blockquote><h4><a name="tag_03_373_12"></a>Issue 5</h4><blockquote><p>Moved from X/OPEN UNIX extension to BASE.</p></blockquote><h4><a name="tag_03_373_13"></a>Issue 6</h4><blockquote><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p><p>The wording of the mandatory [ELOOP] error condition is updated, and a second optional [ELOOP] error condition is added.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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