Filesystem 函数
在线手册：中文 英文
PHP手册

rename

(PHP 4, PHP 5)

rename — 重命名一个文件或目录

说明

bool rename ( string $oldname , string $newname [, resource $context ] )

尝试把 oldname 重命名为 newname。

成功时返回 TRUE， 或者在失败时返回 FALSE.

Example #1 rename() 例子

<?php
rename("/tmp/tmp_file.txt", "/home/user/login/docs/my_file.txt");
?>

Note:

在 PHP 4.3.3 之前，rename() 不能在基于 *nix 的系统中跨磁盘分区重命名文件。

Note: 自 PHP 5.0.0 起 rename() 也可用于某些 URL 封装协议。参见Supported Protocols and Wrappers 的列表看看 rename() 支持哪些 URL 封装协议。

Note: 用于 oldname 中的封装协议必须和用于 newname 中的相匹配。

Note: 在 PHP 5.0.0 中增加了 对上下文(Context)的支持。 有关 上下文(Context) 的说明参见 Streams。

参见 copy()，unlink() 和 move_uploaded_file()。

参数

oldname

Note:

The old name. The wrapper used in oldname must match the wrapper used in newname.

newname

The new name.

context

Note: 在 PHP 5.0.0 中增加了 对上下文(Context)的支持。 有关 上下文(Context) 的说明参见 Streams。

返回值

成功时返回 TRUE， 或者在失败时返回 FALSE.

更新日志

版本 说明
5.3.1 rename() can now rename files across drives in Windows.
5.0.0 rename() can now also be used with some URL wrappers. Refer to Supported Protocols and Wrappers for a listing of which wrappers support rename().
4.3.3 rename() may now be able to rename files across partitions on *nix based systems, provided the appropriate permissions are held. Warnings may be generated if the destination filesystem doesn't permit chown() or chmod() system calls to be made on files — for example, if the destination filesystem is a FAT filesystem.

范例

Example #2 Example with rename()

<?php
rename("/tmp/tmp_file.txt", "/home/user/login/docs/my_file.txt");
?>

参见

Filesystem 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: 重命名一个文件或目录

用户评论:

Andy at txtNation dot com (22-Jan-2012 07:46)

On Linux, I observe that rename retains the original ownership of the file.

I tried rename as root, a file owned by 'Andy' and the newly renamed file was still owned by 'Andy'

I tried rename as 'Bob', a file owned by 'Andy', but writeable by 'Bob', and the newly renamed file was still owned by 'Andy'

thomas dot hebinck at digionline dot de (10-Nov-2011 06:06)

As defined by the underlying protocol, rename() does not overwrite existing files when being used with some wrappers (like SSH2.SFTP).

Martin Pelletier (05-Feb-2011 06:01)

rename() is working on Linux/UNIX but not working on Windows on a directory containing a file formerly opened within the same script. The problem persists even after properly closing the file and flushing the buffer.

<?php
$fp = fopen ("./dir/ex.txt" , "r+");
$text = fread($fp, filesize("../dir/ex.txt"));
ftruncate($fp, 0);
$text2 = "some value";
fwrite ($fp,  $text2 );
fflush($fp);
fclose ($fp);
if (is_resource($fp))
    fclose($fp);
rename ("./dir", ".dir2"); // will give a ?permission denied? error
?>

Strangely it seem that the rename command is  executed BEFORE the handle closing on Windows.

Inserting a sleep() command before the renaming cures the problem.

<?php
$fp = fopen ("./dir/ex.txt" , "r+");
$text = fread($fp, filesize("../dir/ex.txt"));
ftruncate($fp, 0);
$text2 = "some value";
fwrite ($fp,  $text2 );
fflush($fp);
fclose ($fp);
if (is_resource($fp))
    fclose($fp);
sleep(1);    // this does the trick
rename ("./dir", ".dir2"); //no error
?>

andrew at 21cv dot co dot uk (15-Apr-2010 01:19)

Code first, then explanation.

<?php

 rename ("/folder/file.ext", "newfile.ext");

?>

That doesn't rename the file within the folder, as you might assume, instead, it moves the file to whatever the PHP working directory is... Chances are you'll not find it in your FTP tree. Instead, use the following:

<?php

 rename ("/folder/file.ext", "/folder/newfile.ext");

?>

Morteza (10-Apr-2010 08:04)

This code renames all  files and folders in a specific directory to lower case:

<?php
$path = "my_doc";

function getDirectory( $path = '.', $level = 0 ){

    $ignore = array( 'cgi-bin', '.', '..' );

    $dh = @opendir( $path );
   
    while( false !== ( $file = readdir( $dh ) ) )
    {
        if( !in_array( $file, $ignore ) )
        {
            $spaces = str_repeat( '&nbsp;', ( $level * 4 ) );
            if( is_dir( "$path/$file" ) )
            {
                echo "<strong>$spaces $file</strong><br />";
                rename($path."\\".$file, strtolower($path."\\".$file));
                getDirectory( "$path/$file", ($level+1) );
               
            }
            else {
                echo "$spaces $file<br />";
                rename($path."\\".$file, strtolower($path."\\".$file));
            }
        }  
    }
    closedir( $dh );
}

getDirectory( $path , 0 )

?>

pcdinh at phpvietnam dot net (30-Jul-2009 05:10)

For those who are still confused about the behavior of rename() in Linux and Windows (Windows XP) when target destination exists:

I have tested rename($oldName, $targetName) in PHP 5.3.0 and PHP 5.2.9 on both OS and find that if a file named $targetName does exist before, it will be overwritten with the content of $oldName

php-page at mailfilter dot com dot ar (04-Jul-2009 05:06)

In Windows, on FAT32, rename will fail with "bad file descriptor" if the underlying short (8.3) file name of the file to rename is the same as the new file name. For example, attempting to rename "Oxygène.m3u" to "Oxygene.m3u" will fail if the 8.3 name of "Oxygène.m3u" is "OXYGENE.M3U" (which is very likely), as Windows will take both names as belonging to the same file. To solve this you must first rename the file to an intermediate name and then rename it to the intended name. To see the short (8.3) file names in a directory you can type DIR /X on a cmd box.

sudhir dot vis at gmail dot com (27-Apr-2009 10:19)

Rename all the files at one. :)

<?php
$path = "E:\\SERVER\\sudhir\\songs";
$dh = opendir($path);
$i=1;
while (($file = readdir($dh)) !== false) {
    if($file != "." && $file != "..") {
        echo "<br/>".substr($path."\\".$file, 0,-3)."_mysongs_mp3";
        rename($path."\\".$file, substr($path."\\".$file, 0,-3)."_mysongs_mp3");
        $i++;
    }
}
closedir($dh);
?>

andrew at iwebsolutions dot co dot uk (02-Apr-2009 09:36)

Note that this WILL NOT WORK if trying to rename a directory to a network share.

e.g.
rename('/home/user/me/dir1', '/mnt/shares/nfsmount/dir2')

will create a file called 'dir2' on the share and not a directory.

This caught me out and my (quickest) solution was to use an exec and mv command:

<?php
$cmd = 'mv "/home/user/me/dir1" "/mnt/shares/nfsmount/dir2"';
exec($cmd, $output, $return_val);

if ($return_val == 0) {
   echo "success";
} else {
   echo "failed";
}
?>

brent at brenthugh dot com (09-Jan-2009 06:31)

This is an update to the code provided by dev at islam-soft dot com, which renames all files in a directory with a given extension to have a different extension.

I updated four things: Most important, added a check to make sure the extension matched ONLY the end of the filename (the original caused me a number of headaches when it started matching things in the middle of filenames instead of at the end where a proper extension belongs), 2nd added some feedback about what is going on, if you choose verbose mode=TRUE, 3rd added the "testing" parameter so you can do a test run before committing for real, 4th added an error message if a rename fails.

parameter 1 :  the directory name
parameter 2 :  the first extension which we want to replace
parameter 3 :  the new extension of files
parameter 4 :  verbose? (true/false)
parameter 5 :  testing? (true/false)--if true, won't actually rename anything; if you do verbose=TRUE and testing=TRUE you can see what will happen before committing to it with testing=FALSE.

Return is the number of files renamed.

for a simple usage call the function :
changeext('my/directory', 'html', 'php',  false, false);

This changes every file name with extension html  into php  in the directory  my/directory

<?PHP

//changes files in $directory with extension $ext1 to have extension $ext2
//note that if file.ext2 already exists it will simply be over-written
function changeext($directory, $ext1, $ext2, $verbose = false, $testing=true) {
  if ($verbose && $testing) { echo "Testing only . . . <br />";}
  $num = 0;
  if($curdir = opendir($directory)) {
   if ($verbose) echo "Opening $directory . . .<br />";
   while($file = readdir($curdir)) {
     if($file != '.' && $file != '..') {

       $srcfile = $directory . '/' . $file;
       $string  = "$file";
       $str     = strlen($ext1);
       $str++;
       $newfile = substr($string, 0, -$str);
       $newfile = $newfile.'.'.$ext2;
       $dstfile = $directory . '/' . $newfile;

       if (eregi("\.$ext1". '$' ,$file)) { # Look at only files with a pre-defined extension, '$' ensures the ext is only at they end of the filename

         //I think the next two lines are unnecessary but they
         //don't hurt anything so I'm leaving them
         $fileHand = fopen($srcfile, 'r');
         fclose($fileHand);

         if (!$testing) {
            $result=rename($srcfile, $dstfile );
            if (!$result) echo "ERROR renaming $srcfile -> $dstfile<br />";
         }
      

         if ($verbose) echo "$srcfile -> $dstfile<br />";
       }

       if(is_dir($srcfile)) {
         $num += changeext($srcfile, $ext1, $ext2, $verbose, $testing);
       }
     }
   }
   closedir($curdir);
  }
  return $num;
}

$testing=true;
$verbose=true;

//example usages, first run with $testing set to false, then change $testing to true to do them for real:
//changeext('your/directory', 'php', 'html', $verbose,  $testing);
//changeext('your/directory', 'html', 'php',  $verbose, $testing);

garagod at gmail dot com (06-Oct-2008 06:36)

When I'm using unlink() or rename() with a SSH2.SFTP wrapper, both functions always return FALSE (but without a warning) even on success.

Example:

$connection = ssh2_connect(SERVER_NAME, PORT);
ssh2_auth_password($connection, USERNAME, PASSWORD);
$sftp = ssh2_sftp($connection);

unlink("ssh2.sftp://$sftp/" . REMOTE_DIRECTORY . FILENAME); // returns FALSE on success and on failure

rename("ssh2.sftp://$sftp/" . REMOTE_DIRECTORY . OLD_FILENAME, "ssh2.sftp://$sftp/" . REMOTE_DIRECTORY . NEW_FILENAME); // returns FALSE on success and on failure

Francois Hill (17-Sep-2008 05:26)

In response to
treshugart at gmail dot com
(06-Feb-2008 02:09)

"Apparently rename() will fail on filenames that are too large and emit an E_WARNING."

This may not necessarily be php's rename's fault. (well ...)

On Windows systems for example you have a file name limit at 255 caracters. Since rename relies on the system's underlying layer, it will fail if that happens, leaving your directory and files 'in limbo' ... (I haven't looked into the details but I don't think rename incorporates a rollback strategy).
One could think of other reasons too (rights, etc.), I'm not sure how rename would react then.

Hence, as a general rule, when working on folders or sensible data where no rollback support is provided, it is a good idea to always work on a copy. (or make a backup)

Whooptydoo (08-Jul-2008 05:11)

If by any chance you end up with something equivalent to this:

<?php
rename('/foo/bar','/foo/bar');
?>

It returns true. It's not documented.

chris at no_email_is_relevant dot com (23-Jun-2008 02:39)

If you want a quick alternative to rename folders with php under Windows:

Open a dos command prompt and use the REN (rename) command of Windows.

$output = pclose(popen("start /B cmd /C REN C:\folder\to\rename newName 2>&1", "r"));

Remark: This command needs \ in the path name.

treshugart at gmail dot com (06-Feb-2008 01:09)

This might be a similar problem to what happened to:

jmalinsky at gmail dot com
10-Dec-2005 08:41

Apparently rename() will fail on filenames that are too large and emit an E_WARNING.

I was using rename() 'batch-move' a bunch of images. These files were lost in translation; in other words: deleted. One file, however, was moved but the filename was truncated. Weird. Why one or two files while the rest were deleted. This was being attempted on a Windows box.

I hope this helps anyone. If anyone has an explanation please feel free to email me. But if you're one of those idiots who *thinks* they're better than everyone and you *think* you know everything, don't bother.

surfchen at gmail dot com (13-Dec-2007 02:52)

It will not work if rename the dir on partitionA to the dir on partitionB.
Because if source and target on different partition,rename() will firstly call the copy().

jeppe at bundsgaard dot net (12-Jan-2007 09:50)

Until recently you could end the dirname your wanted to rename to with a slash:

rename("mydir/my2nddir/","mydir/my3nddir/")

But now it doesn't work (php warns that it is unable to access mydir/my3nddir/).

So always leave out a final slash in your dirname:

rename("mydir/my2nddir","mydir/my3nddir")

The same goes for mkdir().

dev at islam-soft dot com (05-Jan-2007 12:52)

- rename extension of files

changeext($directory, $ext1, $ext2, $verbose)

i wrote this function to rename the extention of some files in a folder and sub-folders inside it ..

parameter 1 :  the directory name
parameter 2 :  the first extention wich we want to replace
parameter 3 :  the new extention of files

for a simple usage call the function :
changeext('dir', 'html', 'php',  'false');

to change evry file name with extention html  into php  in the directory  dir

<?php

function changeext($directory, $ext1, $ext2, $verbose = false) {
  $num = 0;
  if($curdir = opendir($directory)) {
   while($file = readdir($curdir)) {
     if($file != '.' && $file != '..') {

       $srcfile = $directory . '/' . $file;
       $string  = "$file";
       $str     = strlen($ext1);
       $str++;
       $newfile = substr($string, 0, -$str);
       $newfile = $newfile.'.'.$ext2;
       $dstfile = $directory . '/' . $newfile;

       if (eregi("\.$ext1",$file)) { # Look at only files with a pre-defined extension
       $fileHand = fopen($srcfile, 'r');
       fclose($fileHand);
       rename($srcfile, $dstfile );
       }

       if(is_dir($srcfile)) {
         $num += changeext($srcfile, $ext1, $ext2, $verbose);
       }
     }
   }
   closedir($curdir);
  }
  return $num;
}

changeext('dir', 'html', 'php',  'false');

?>

to remove the extention of files , just leave the parameter $ext2 blank ''

Eric (Themepark.com) (03-Nov-2006 06:31)

This was a fun one-- on Win XP, rename throws a "permission deined" if you try to rename across volumes.. i.e. rename("c:\windows\temp\x.txt", "g:\destination") will fail.

David Thole (root at thedarktrumpet.com) (22-Oct-2006 08:20)

As of PHP 5.1.4 compiled on a mac, using rename with spaces one should just use the space.   Take for example:

rename("/tmp/somefile.tar", "/mnt/laptop storage/somefile.tar");

If you use the backslash, like if you were cd-ing to the directory, rename will fail.  Example:

rename("/tmp/somefile.tar", "/mnt/laptop\ storage/somefile.tar");

While not really a bug, it did confuse me for a little bit while working on a backup script.

PHP at Drarok dot com (08-Aug-2006 09:57)

As described from the unlink() page:
You have to release any handles to the file before you can rename it (True on Windows, at least).
This will NOT work, you'll receive permission denied errors:
<?php
    $fileHand = fopen('tempFile.txt', 'r');
    rename( 'tempFile.txt', 'tempFile2.txt' ); // Permission Denied!
?>

Simply close the handle to fix this:
<?php
    $fileHand = fopen('tempFile.txt', 'r');
    fclose($fileHand);
    rename( 'tempFile.txt', 'tempFile2.txt' );
?>

This has me scratching my head for some time, as the handle was opened at the top of a marge function, and the rename was at the bottom.

kitty_zoso at NOSPAMyahoo dot com (01-Feb-2006 07:45)

Beware of rename if you're interested in preserving the case of filenames.  I'm writing a backup application using the command line version of php 5 on Windows XP and wanted to detect when the case of a source dir entry changed so I could rename it on the backup drive.

For instance, \common\kathy has been renamed to \common\Kathy on the source drive, so I wanted to rename the target directory, so a restore operation will have the new name to use.  The rename function didn't return false, but didn't change the case of the entry!  As a workaround (ugh) I change it to "something else" then do the final rename: instead of

rename('kathy','Kathy');

I use

rename('kathy', '~kathy~');
rename('~kathy~', 'Kathy');

bobbfwed at comcast dot net (26-Jan-2006 08:30)

I have programmed a really nice program that remotely lets you manage files as if you have direct access to them (http://sourceforge.net/projects/filemanage/). I have a bunch of really handy functions to do just about anything to files or directories. In it I just finished redevloping the directory move function to utilize PHP's rename() since it is way more efficient than a copy/delete process. It goes through (recursivly) and renames all the files to a new location instead of copying them. It recreates the directory structure in the new location. It also allows you to overwrite the existing files, or not.
Here is the function I made; it will likely need tweaking to work as a standalone script, since it relies of variables set by my program (eg: loc1 -- which dynamically changes in my program):

<?PHP
  // loc1 is the path on the computer to the base directory that may be moved
define('loc1', 'C:/Program Files/Apache Group/Apache/htdocs', true);

  // move a directory and all subdirectories and files (recursive)
  // void dirmv( str 'source directory', str 'destination directory' [, bool 'overwrite existing files' [, str 'location within the directory (for recurse)']] )
function dirmv($source, $dest, $overwrite = false, $funcloc = NULL){

  if(is_null($funcloc)){
    $dest .= '/' . strrev(substr(strrev($source), 0, strpos(strrev($source), '/')));
    $funcloc = '/';
  }

  if(!is_dir(loc1 . $dest . $funcloc))
    mkdir(loc1 . $dest . $funcloc); // make subdirectory before subdirectory is copied

  if($handle = opendir(loc1 . $source . $funcloc)){ // if the folder exploration is sucsessful, continue
    while(false !== ($file = readdir($handle))){ // as long as storing the next file to $file is successful, continue
      if($file != '.' && $file != '..'){
        $path  = $source . $funcloc . $file;
        $path2 = $dest . $funcloc . $file;

        if(is_file(loc1 . $path)){
          if(!is_file(loc1 . $path2)){
            if(!@rename(loc1 . $path, loc1 . $path2)){
              echo '<font color="red">File ('.$path.') could not be moved, likely a permissions problem.</font>';
            }
          } elseif($overwrite){
            if(!@unlink(loc1 . $path2)){
              echo 'Unable to overwrite file ("'.$path2.'"), likely to be a permissions problem.';
            } else
              if(!@rename(loc1 . $path, loc1 . $path2)){
                echo '<font color="red">File ('.$path.') could not be moved while overwritting, likely a permissions problem.</font>';
              }
          }
        } elseif(is_dir(loc1 . $path)){
          dirmv($source, $dest, $overwrite, $funcloc . $file . '/'); //recurse!
          rmdir(loc1 . $path);
        }
      }
    }
    closedir($handle);
  }
} // end of dirmv()
?>

This new function will be in 0.9.7 (the next release of File Manage) which should release sometime early February.
Hope this helps some people.

php at froghh dot de (19-Jan-2006 11:00)

Remark for "php at stock-consulting dot com"'s note:
This depends on the operating system.
On windows-systems you can't rename a file to an existing destination (ok, with tools you can - but they unlink the exisiting one before).

php at stock-consulting dot com (04-Jan-2006 10:36)

rename() fails with PHP4 and PHP5 under Windows if the destination file exists, regardless of file permission settings. I now use a function similar to that of ddoyle [at] canadalawbook [dot] ca, which first tries rename(), checks if it returned FALSE and then uses copy()/unlink() if it failed.

However, copy() is, unlike rename(), NOT useable for "atomic updates". Another process may actually access the destination file while copy() is working. In such a case, the other process with perceive the file as empty or with incomplete content ("half written").

php-public at macfreek dot nl (18-Dec-2005 07:33)

It is unclear what encoding the arguments of rename should have; For PHP 4.3, on a HFS+ filesystems, rename() did not handle UTF-8 strings, and returned an error.

jmalinsky at gmail dot com (09-Dec-2005 09:41)

On WinXP/PHP 5+, not only does rename()  not follow the *nix rename as noted below, but other things (do not) happen.  If you're trying to rename a directory, files within the directory will NOT be present in the renamed directory, though sub-directories WILL be present.  Ultra-strange.  And as noted, your 'old' directory will remain on the server totally intact, which can be very confusing.

To try and rename a folder on XP via PHP, I wound up using a workaround: first i used the copydirr() function posted by makarenkoa at ukrpost dot net on the "copy" page of the online manual to copy all folders and files within the original directory to the new one... and then to delete the original directory (and all files/folders beneath it), i used the delDir() function corrected by czambran at gmail dot com on the "rmdir" page of the online manual.  Why didn't I use unlink()?  Because, unlink does NOT work on Windows systems either (and even if it did work, its not recursive without extra coding).

So, all in all, rename() is pretty much a useless function if you are intending to rename a folder on an XP box.

tbrillon at gmail dot com (14-Sep-2005 09:27)

I needed to move a file to another folder regardless if that file existed in the target already so I wrote a small piece to append a unique number to each file.

$rem = $_GET['file'];
$ticket = uniqid(rand(), true);

rename("$rem", "www/home/storefile/$ticket$rem");

the output looks like this - 6881432893ad4925a1.70147481filename.txt

This also helps if you want different versions of the file stored.

ddoyle [at] canadalawbook [dot] ca (07-Sep-2005 11:35)

rename() definitely does not follow the *nix rename convention on WinXP with PHP 5.  If the $newname exists, it will return FALSE and $oldname and $newname will remain in their original state.  You can do something like this instead:

function rename_win($oldfile,$newfile) {
   if (!rename($oldfile,$newfile)) {
      if (copy ($oldfile,$newfile)) {
         unlink($oldfile);
         return TRUE;
      }
      return FALSE;
   }
   return TRUE;
}

tomfelker at gmail dot com (11-Aug-2005 10:51)

Actually, I'm pretty sure that rename follows the convention of *nix rename(2) in overwriting the destination if it exists atomically (meaning that no other process will see the destination cease to exist, even for an instant).  This is useful because it allows you to build a file as a temp file, then rename it to where you want it to be, and nobody sees the file when it's half done.

Probably rename($old, $new) with an existing new was caused by permission problems.  I bet the other problems you had were the result of not calling clearstatcache(), which can cause PHP to act like a file exists though it has since been deleted.

JRog (27-May-2005 07:44)

To anyone wondering, rename($old, $new) returns FALSE if $new already exists.  My script called for overwriting the file if it existed so I did this:

if(file_exists($new)) { unlink($new); }
$ok = rename($old, $new);

This did not work as expected.  If $new actually existed then it worked fine.  That is the file found at path $new was deleted and replaced with the file found at path $old.  However, if $new did NOT exist then the result was the file at  path $old vanished into oblivion.  After debugging a bit, it seems that rename() was getting executed before the if-statement.  So rename() moved $old to $new, THEN the if-statement evaluated to true and deleted the file I just moved.  Anyway, this fixed it:

if(file_exists($new)) {
    unlink($new);
    $ok = rename($old, $new);
} else { $ok = rename($old, $new); }

Very strange ... I hope this helps somebody

sophie at sitadelle dot com (14-Nov-2003 04:22)

Hello!
For unix/linux users: it is usefull to know that if you use rename() for a directory, the new one will be created with the current umask!

blujay (08-Feb-2002 09:32)

You can always chdir() to the parent directory of what you're renaming, and rename the directory or file directly.  For example:

$oldWD = getcwd();
chdir($dirWhereRenameeIs);
rename($oldFilename, $newFilename);
chdir($oldWD);

pearcec at commnav dot com (15-Jun-2001 09:17)

If you rename one directory to another where the second directory exists as an empty directory it will not complain.

Not what I expected.

[pearcec@abe tmp]$ mkdir test1
[pearcec@abe tmp]$ mkdir test2
[pearcec@abe tmp]$ touch test1/test
[pearcec@abe tmp]$ php
<?php
rename("test1","test2");
?>
X-Powered-By: PHP/4.0.5
Content-type: text/html

[pearcec@abe tmp]$ ls -al
total 12
drwxr-xr-x    3 pearcec  commnav      4096 Jun 15 13:17 .
drwxr-xr-x   18 pearcec  commnav      4096 Jun 15 13:15 ..
drwxr-xr-x    2 pearcec  commnav      4096 Jun 15 13:16 test2
[pearcec@abe tmp]$ ls -la test2/
total 8
drwxr-xr-x    2 pearcec  commnav      4096 Jun 15 13:16 .
drwxr-xr-x    3 pearcec  commnav      4096 Jun 15 13:17 ..
-rw-r--r--    1 pearcec  commnav         0 Jun 15 13:16 test
[pearcec@abe tmp]$

michael-nospam at sal dot mik dot hyperlink dot net dot au (25-Nov-1999 07:43)

Note, that on Unix, a rename is a beautiful way of getting atomic updates to files.

Just copy the old contents (if necessary), and write the new contents into a new file, then rename over the original file.

Any processes reading from the file will continue to do so, any processes trying to open the file while you're writing to it will get the old file (because you'll be writing to a temp file), and there is no "intermediate" time between there being a file, and there not being a file (or there being half a file).

Oh, and this only works if you have the temp file and the destination file on the same filesystem (eg. partition/hard-disk).