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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>stat</title></head><body bgcolor="white"><basefont size="3"> <a name="stat"></a> <a name="tag_03_716"></a><!-- stat --> <!--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_716_01"></a>NAME</h4><blockquote>stat - get file status</blockquote><h4><a name="tag_03_716_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/sys/stat.h.html">sys/stat.h</a>><br><br> int stat(const char *restrict</tt> <i>path</i><tt>, struct stat *restrict</tt> <i>buf</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_716_03"></a>DESCRIPTION</h4><blockquote><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>argument. The <i>path</i> argument points to a pathname naming a file. Read, write, or execute permission of the named file is notrequired. An implementation that provides additional or alternate file access control mechanisms may, under implementation-definedconditions, cause <i>stat</i>() to fail. In particular, the system may deny the existence of the file specified by <i>path</i>.</p><p>If the named file is a symbolic link, the <i>stat</i>() function shall continue pathname resolution using the contents of thesymbolic link, and shall return information pertaining to the resulting file if the file exists.</p><p>The <i>buf</i> argument is a pointer to a <b>stat</b> structure, as defined in the <a href="../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a> header, into which information is placed concerning the file.</p><p>The <i>stat</i>() function shall update any time-related fields (as described in the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap04.html#tag_04_07">Section 4.7, File Times Update</a>), before writinginto the <b>stat</b> structure.</p><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>,<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 ofIEEE 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></blockquote><h4><a name="tag_03_716_04"></a>RETURN VALUE</h4><blockquote><p>Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and <i>errno</i> set to indicate the error.</p></blockquote><h4><a name="tag_03_716_05"></a>ERRORS</h4><blockquote><p>The <i>stat</i>() function shall fail if:</p><dl compact><dt>[EACCES]</dt><dd>Search permission is denied for a component of the path prefix.</dd><dt>[EIO]</dt><dd>An error occurred while reading from 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 the <i>path</i> argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.</dd><dt>[ENOENT]</dt><dd>A component of <i>path</i> does not name an existing file or <i>path</i> is an empty string.</dd><dt>[ENOTDIR]</dt><dd>A component of the path prefix is not a directory.</dd><dt>[EOVERFLOW]</dt><dd>The file size in bytes or the number of blocks allocated to the file or the file serial number cannot be represented correctlyin the structure pointed to by <i>buf</i>.</dd></dl><p>The <i>stat</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>As a result of encountering a symbolic link in resolution of the <i>path</i> argument, the length of the substituted pathnamestring exceeded {PATH_MAX}.</dd><dt>[EOVERFLOW]</dt><dd>A value to be stored would overflow one of the members of the <b>stat</b> structure.</dd></dl></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_716_06"></a>EXAMPLES</h4><blockquote><h5><a name="tag_03_716_06_01"></a>Obtaining File Status Information</h5><p>The following example shows how to obtain file status information for a file named <b>/home/cnd/mod1</b>. The structure variable<i>buffer</i> is defined for the <b>stat</b> structure.</p><pre><tt>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h><br>struct stat buffer;int status;...status = stat("/home/cnd/mod1", &buffer);</tt></pre><h5><a name="tag_03_716_06_02"></a>Getting Directory Information</h5><p>The following example fragment gets status information for each entry in a directory. The call to the <i>stat</i>() functionstores file information in the <b>stat</b> structure pointed to by <i>statbuf</i>. The lines that follow the <i>stat</i>() callformat the fields in the <b>stat</b> structure for presentation to the user of the program.</p><pre><tt>#include <sys/types.h>#include <sys/stat.h>#include <dirent.h>#include <pwd.h>#include <grp.h>#include <time.h>#include <locale.h>#include <langinfo.h>#include <stdio.h>#include <stdint.h><br>struct dirent *dp;struct stat statbuf;struct passwd *pwd;struct group *grp;struct tm *tm;char datestring[256];.../* Loop through directory entries. */while ((dp = readdir(dir)) != NULL) {<br> /* Get entry's information. */ if (stat(dp->d_name, &statbuf) == -1) continue;<br> /* Print out type, permissions, and number of links. */ printf("%10.10s", sperm (statbuf.st_mode)); printf("%4d", statbuf.st_nlink);<br> /* Print out owner's name if it is found using getpwuid(). */ if ((pwd = getpwuid(statbuf.st_uid)) != NULL) printf(" %-8.8s", pwd->pw_name); else printf(" %-8d", statbuf.st_uid);<br> /* Print out group name if it is found using getgrgid(). */ if ((grp = getgrgid(statbuf.st_gid)) != NULL) printf(" %-8.8s", grp->gr_name); else printf(" %-8d", statbuf.st_gid);<br> /* Print size of file. */ printf(" %9jd", (intmax_t)statbuf.st_size);<br> tm = localtime(&statbuf.st_mtime);<br> /* Get localized date string. */ strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);<br> printf(" %s %s\n", datestring, dp->d_name);}</tt></pre></blockquote><h4><a name="tag_03_716_07"></a>APPLICATION USAGE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_716_08"></a>RATIONALE</h4><blockquote><p>The intent of the paragraph describing "additional or alternate file access control mechanisms" is to allow a secureimplementation where a process with a label that does not dominate the file's label cannot perform a <i>stat</i>() function. Thisis not related to read permission; a process with a label that dominates the file's label does not need read permission. Animplementation that supports write-up operations could fail <a href="../functions/fstat.html"><i>fstat</i>()</a> function callseven though it has a valid file descriptor open for writing.</p></blockquote><h4><a name="tag_03_716_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_716_10"></a>SEE ALSO</h4><blockquote><p><a href="fstat.html"><i>fstat</i>()</a> , <a href="lstat.html"><i>lstat</i>()</a> , <a href="readlink.html"><i>readlink</i>()</a> , <a href="symlink.html"><i>symlink</i>()</a> , the Base Definitions volume ofIEEE Std 1003.1-2001, <a href="../basedefs/sys/stat.h.html"><i><sys/stat.h></i></a>, <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a></p></blockquote><h4><a name="tag_03_716_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_716_12"></a>Issue 5</h4><blockquote><p>Large File Summit extensions are added.</p></blockquote><h4><a name="tag_03_716_13"></a>Issue 6</h4><blockquote><p>In the SYNOPSIS, the optional include of the <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> header isremoved.</p><p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p><ul><li><p>The requirement to include <a href="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> has been removed. Although <ahref="../basedefs/sys/types.h.html"><i><sys/types.h></i></a> was required for conforming implementations of previous POSIXspecifications, it was not required for UNIX applications.</p></li><li><p>The [EIO] mandatory error condition is added.</p></li><li><p>The [ELOOP] mandatory error condition is added.</p></li><li><p>The [EOVERFLOW] mandatory error condition is added. This change is to support large files.</p></li><li><p>The [ENAMETOOLONG] and the second [EOVERFLOW] optional error conditions are added.</p></li></ul><p>The following changes were made to align with the IEEE P1003.1a draft standard:</p><ul><li><p>Details are added regarding the treatment of symbolic links.</p></li><li><p>The [ELOOP] optional error condition is added.</p></li></ul><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p><p>The <b>restrict</b> keyword is added to the <i>stat</i>() prototype for alignment with the ISO/IEC 9899:1999 standard.</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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