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311 lines
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>stat</title>
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<basefont size="3"> <a name="stat"></a> <a name="tag_03_716"></a><!-- stat -->
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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_716_01"></a>NAME</h4>
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<blockquote>stat - get file status</blockquote>
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<h4><a name="tag_03_716_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 stat(const char *restrict</tt> <i>path</i><tt>, struct stat *restrict</tt> <i>buf</i><tt>);<br>
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</tt></code></p>
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</blockquote>
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<h4><a name="tag_03_716_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>The <i>stat</i>() function shall obtain information about the named file and write it to the area pointed to by the <i>buf</i>
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argument. The <i>path</i> argument points to a pathname naming a file. Read, write, or execute permission of the named file is not
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required. An implementation that provides additional or alternate file access control mechanisms may, under implementation-defined
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conditions, cause <i>stat</i>() to fail. In particular, the system may deny the existence of the file specified by <i>path</i>.</p>
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<p>If the named file is a symbolic link, the <i>stat</i>() function shall continue pathname resolution using the contents of the
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symbolic link, and shall return information pertaining to the resulting file if the file exists.</p>
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<p>The <i>buf</i> argument is a pointer to a <b>stat</b> structure, as defined in the <a href=
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"../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a> header, into which information is placed concerning the file.</p>
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<p>The <i>stat</i>() function shall update any time-related fields (as described in the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap04.html#tag_04_07">Section 4.7, File Times Update</a>), before writing
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into the <b>stat</b> structure.</p>
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<p>Unless otherwise specified, the structure members <i>st_mode</i>, <i>st_ino</i>, <i>st_dev</i>, <i>st_uid</i>, <i>st_gid</i>,
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<i>st_atime</i>, <i>st_ctime</i>, and <i>st_mtime</i> shall have meaningful values for all file types defined in this volume of
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IEEE Std 1003.1-2001. The value of the member <i>st_nlink</i> shall be set to the number of links to the file.</p>
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</blockquote>
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<h4><a name="tag_03_716_04"></a>RETURN VALUE</h4>
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<blockquote>
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<p>Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and <i>errno</i> set to indicate the error.</p>
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</blockquote>
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<h4><a name="tag_03_716_05"></a>ERRORS</h4>
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<blockquote>
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<p>The <i>stat</i>() function shall fail if:</p>
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<dl compact>
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<dt>[EACCES]</dt>
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<dd>Search permission is denied for a component of the path prefix.</dd>
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<dt>[EIO]</dt>
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<dd>An error occurred while reading from the file system.</dd>
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<dt>[ELOOP]</dt>
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<dd>A loop exists in symbolic links encountered during resolution of the <i>path</i> argument.</dd>
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<dt>[ENAMETOOLONG]</dt>
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<dd>
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The length of the <i>path</i> argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.</dd>
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<dt>[ENOENT]</dt>
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<dd>A component of <i>path</i> does not name an existing file or <i>path</i> is an empty string.</dd>
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<dt>[ENOTDIR]</dt>
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<dd>A component of the path prefix is not a directory.</dd>
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<dt>[EOVERFLOW]</dt>
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<dd>The file size in bytes or the number of blocks allocated to the file or the file serial number cannot be represented correctly
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in the structure pointed to by <i>buf</i>.</dd>
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</dl>
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<p>The <i>stat</i>() function may fail if:</p>
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<dl compact>
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<dt>[ELOOP]</dt>
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<dd>More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the <i>path</i> argument.</dd>
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<dt>[ENAMETOOLONG]</dt>
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<dd>
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As a result of encountering a symbolic link in resolution of the <i>path</i> argument, the length of the substituted pathname
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string exceeded {PATH_MAX}.</dd>
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<dt>[EOVERFLOW]</dt>
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<dd>A value to be stored would overflow one of the members of the <b>stat</b> structure.</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_716_06"></a>EXAMPLES</h4>
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<blockquote>
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<h5><a name="tag_03_716_06_01"></a>Obtaining File Status Information</h5>
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<p>The following example shows how to obtain file status information for a file named <b>/home/cnd/mod1</b>. The structure variable
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<i>buffer</i> is defined for the <b>stat</b> structure.</p>
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<pre>
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<tt>#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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<br>
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struct stat buffer;
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int status;
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...
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status = stat("/home/cnd/mod1", &buffer);
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</tt>
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</pre>
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<h5><a name="tag_03_716_06_02"></a>Getting Directory Information</h5>
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<p>The following example fragment gets status information for each entry in a directory. The call to the <i>stat</i>() function
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stores file information in the <b>stat</b> structure pointed to by <i>statbuf</i>. The lines that follow the <i>stat</i>() call
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format the fields in the <b>stat</b> structure for presentation to the user of the program.</p>
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<pre>
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<tt>#include <sys/types.h>
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#include <sys/stat.h>
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#include <dirent.h>
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#include <pwd.h>
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#include <grp.h>
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#include <time.h>
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#include <locale.h>
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#include <langinfo.h>
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#include <stdio.h>
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#include <stdint.h>
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<br>
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struct dirent *dp;
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struct stat statbuf;
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struct passwd *pwd;
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struct group *grp;
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struct tm *tm;
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char datestring[256];
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...
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/* Loop through directory entries. */
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while ((dp = readdir(dir)) != NULL) {
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<br>
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/* Get entry's information. */
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if (stat(dp->d_name, &statbuf) == -1)
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continue;
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<br>
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/* Print out type, permissions, and number of links. */
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printf("%10.10s", sperm (statbuf.st_mode));
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printf("%4d", statbuf.st_nlink);
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<br>
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/* Print out owner's name if it is found using getpwuid(). */
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if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
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printf(" %-8.8s", pwd->pw_name);
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else
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printf(" %-8d", statbuf.st_uid);
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<br>
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/* Print out group name if it is found using getgrgid(). */
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if ((grp = getgrgid(statbuf.st_gid)) != NULL)
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printf(" %-8.8s", grp->gr_name);
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else
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printf(" %-8d", statbuf.st_gid);
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<br>
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/* Print size of file. */
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printf(" %9jd", (intmax_t)statbuf.st_size);
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<br>
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tm = localtime(&statbuf.st_mtime);
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<br>
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/* Get localized date string. */
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strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);
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<br>
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printf(" %s %s\n", datestring, dp->d_name);
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}
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_03_716_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_716_08"></a>RATIONALE</h4>
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<blockquote>
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<p>The intent of the paragraph describing "additional or alternate file access control mechanisms" is to allow a secure
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implementation where a process with a label that does not dominate the file's label cannot perform a <i>stat</i>() function. This
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is not related to read permission; a process with a label that dominates the file's label does not need read permission. An
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implementation that supports write-up operations could fail <a href="../functions/fstat.html"><i>fstat</i>()</a> function calls
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even though it has a valid file descriptor open for writing.</p>
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</blockquote>
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<h4><a name="tag_03_716_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_716_10"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="fstat.html"><i>fstat</i>()</a> , <a href="lstat.html"><i>lstat</i>()</a> , <a href=
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"readlink.html"><i>readlink</i>()</a> , <a href="symlink.html"><i>symlink</i>()</a> , the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a>, <a href=
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"../basedefs/sys/types.h.html"><i><sys/types.h></i></a></p>
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</blockquote>
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<h4><a name="tag_03_716_11"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
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</blockquote>
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<h4><a name="tag_03_716_12"></a>Issue 5</h4>
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<blockquote>
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<p>Large File Summit extensions are added.</p>
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</blockquote>
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<h4><a name="tag_03_716_13"></a>Issue 6</h4>
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<blockquote>
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<p>In the SYNOPSIS, the optional include of the <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> header is
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removed.</p>
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<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>
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<ul>
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<li>
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<p>The requirement to include <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> has been removed. Although <a
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href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> was required for conforming implementations of previous POSIX
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specifications, it was not required for UNIX applications.</p>
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</li>
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<li>
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<p>The [EIO] mandatory error condition is added.</p>
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</li>
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<li>
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<p>The [ELOOP] mandatory error condition is added.</p>
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</li>
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<li>
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<p>The [EOVERFLOW] mandatory error condition is added. This change is to support large files.</p>
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</li>
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<li>
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<p>The [ENAMETOOLONG] and the second [EOVERFLOW] optional error conditions are added.</p>
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</li>
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</ul>
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<p>The following changes were made to align with the IEEE P1003.1a draft standard:</p>
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<ul>
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<li>
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<p>Details are added regarding the treatment of symbolic links.</p>
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</li>
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<li>
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<p>The [ELOOP] optional error condition is added.</p>
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</li>
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</ul>
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<p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p>
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<p>The <b>restrict</b> keyword is added to the <i>stat</i>() prototype for alignment with the ISO/IEC 9899:1999 standard.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<hr size="2" noshade>
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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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