PHP: stat - Manual

Description

array stat ( string filename )

Gathers the statistics of the file named by filename. If filename is a symbolic link, statistics are from the file itself, not the symlink. lstat() is identical to stat() except it would instead be based off the symlinks status.

In case of error, stat() returns FALSE. It also will throw a warning.

Returns an array with the statistics of the file with the following elements. This array is zero-based. In addition to returning these attributes in a numeric array, they can be accessed with associative indices, as noted next to each parameter; this is available since PHP 4.0.6:

Tabela 1. stat() and fstat() result format

Numeric	Associative (since PHP 4.0.6)	Description
0	dev	device number
1	ino	inode number
2	mode	inode protection mode
3	nlink	number of links
4	uid	userid of owner
5	gid	groupid of owner
6	rdev	device type, if inode device *
7	size	size in bytes
8	atime	time of last access (Unix timestamp)
9	mtime	time of last modification (Unix timestamp)
10	ctime	time of last inode change (Unix timestamp)
11	blksize	blocksize of filesystem IO *
12	blocks	number of blocks allocated

* - only valid on systems supporting the st_blksize type--other systems (i.e. Windows) return -1.

Notatka: Wyniki działania tej funkcji są buforowane. Zobacz opis funkcji clearstatcache() aby uzyskać więcej informacji.

Podpowiedź: Od wersji 5.0.0 PHP ta funkcja może być użyta także z niektórymi wrapperami URL. Zobacz Dodatek L aby uzyskać listę wrapperów które obsługują funkcjonalność z rodziny stat().

User Contributed Notes


If you want to know a directory size, this function will help you:



<?

function dir_size($dir)

{

    $handle = opendir($dir);

    

    while ($file = readdir($handle)) {

        if ($file != '..' && $file != '.' && !is_dir($dir.'/'.$file)) {

            $mas += filesize($dir.'/'.$file);

            } else if (is_dir($dir.'/'.$file) && $file != '..' && $file != '.') {

            $mas += dir_size($dir.'/'.$file);

        }

    }

    return $mas;

}

echo dir_size('DIRECTORIO').' Bytes';

?>


There's an important (yet little-known) problem with file dates on Windows and Daylight Savings. This affects the 'atime' and 'mtime' elements returned by stat(), and it also affects other filesystem-related functions such as fileatime() and filemtime().



During the winter months (when Daylight Savings isn't in effect), Windows will report a certain timestamp for a given file. However, when summer comes and Daylight Savings starts, Windows will report a DIFFERENT timestamp! Even if the file hasn't been altered at all, Windows will shift every timestamp it reads forward one full hour during Daylight Savings.



This all stems from the fact that M$ decided to use a hackneyed method of tracking file dates to make sure there are no ambiguous times during the "repeated hour" when DST ends in October, maintain compatibility with older FAT partitions, etc. An excellent description of what/why this is can be found at http://www.codeproject.com/datetime/dstbugs.asp



This is noteworthy because *nix platforms don't have this problem. This could introduce some hard-to-track bugs if you're trying to move scripts that track file timestamps between platforms.



I spent a fair amount of time trying to debug one of my own scripts that was suffering from this problem. I was storing file modification times in a MySQL table, then using that information to see which files had been altered since the last run of the script. After each Daylight Savings change, every single file the script saw was considered "changed" since the last run, since all the timestamps were off by +/- 3600 seconds.



This one-liner is probably one of the most incorrect fixes that could ever be devised, but it's worked flawlessly in production-grade environments... Assuming $file_date is a Unix timestamp you've just read from a file:



<?php

    if (date('I') == 1) $file_date -= 3600;

?>



That will ensure that the timestamp you're working with is always consistently reported, regardless of whether the machine is in Daylight Savings or not.


Re note posted by "salisbm at hotmail dot com":



S_IFDIR is not a single-bit flag. It is a constant that relies on the "S_IFMT" bitmask. This bitmask should be applied to the "mode" parameter before comparing with any of the other "S_IF..." constants, as indicated by stat.h:



#define S_ISDIR(m)  (((m) & S_IFMT) == S_IFDIR)



That is, this approach is incorrect:



<?php

define('S_IFDIR',040000);

if ($mode & S_IFDIR)

{

  /*

    incorrect!

    format could be S_IFDIR, but also

    S_IFBLK, S_IFSOCK, or S_IFWHT.

  */

}

?>



...and should instead be:



<?php

define('S_IFMT',0170000);

define('S_IFDIR',040000);

if (S_IFDIR == ($mode & S_IFMT)) {  /* ... */  }

?>



As pointed out by "svend at svendtofte dot com", however, there is also the "is_dir" function for this purpose, along with "is_file" and "is_link" to cover the most common format types...


If you are working with files larger than 2GB (and PHP's integer type is only 32 bits on your system) then you can try the following to get floating point sizes:



On FreeBSD:



$size = (float) exec ('stat -f %z '. escapeshellarg ($path));



On Linux:



$size = (float) exec ('stat -c %s '. escapeshellarg ($path));



(The other example that uses "ls" and "awk" does not properly escape the filename, but should work otherwise.)


If you have ftp (and the related sftp) protocols disabled on your remote server, it can be hard figuring out how to 'stat' a remote file. The following works for me:



<?php  



$conn = ssh2_connect($host, 22);

ssh2_auth_password($conn, $user, $password);

$stream = ssh2_exec($conn, "stat $fileName > $remotedest");

ssh2_scp_recv($conn, $remotedest, $localdest);

$farray = file($localdest);

print_r($farray);

?>


I was curious how I could tell if a file was a directory... so I found on http://www.hmug.org/man/2/stat.html the following information about the mode bits:

#define S_IFMT 0170000           /* type of file */

#define        S_IFIFO  0010000  /* named pipe (fifo) */

#define        S_IFCHR  0020000  /* character special */

#define        S_IFDIR  0040000  /* directory */

#define        S_IFBLK  0060000  /* block special */

#define        S_IFREG  0100000  /* regular */

#define        S_IFLNK  0120000  /* symbolic link */

#define        S_IFSOCK 0140000  /* socket */

#define        S_IFWHT  0160000  /* whiteout */

#define S_ISUID 0004000  /* set user id on execution */

#define S_ISGID 0002000  /* set group id on execution */

#define S_ISVTX 0001000  /* save swapped text even after use */

#define S_IRUSR 0000400  /* read permission, owner */

#define S_IWUSR 0000200  /* write permission, owner */

#define S_IXUSR 0000100  /* execute/search permission, owner */



Note that these numbers are in octal format.  Then, to check to see if the file is a directory, after calling fstat, I do:



if ($fstats[mode] & 040000)

  ... this must be a directory


Here's what the UNIX man page on stat has to say about the difference between a file change and  a file modification:





st_mtime  Time when data was last modified.  Changed by  the following  functions:   creat(),  mknod(), pipe(), utime(), and write(2).





st_ctime  Time when file status was last  changed.   Changed by  the  following  functions: chmod(), chown(), creat(), link(2), mknod(), pipe(), unlink(2), utime(), and write().





So a modification is a change in the data, whereas a change also happens if you modify file permissions and so on.