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PHP Quiz PHP CertificatePHP flock() Function
Complete PHP Filesystem Reference
Definition and Usage
The flock() function locks or releases a file.
This function returns TRUE on success or FALSE on failure.
Syntax
flock(file,lock,block)
| Parameter | Description |
|---|---|
| file | Required. Specifies an open file to lock or release |
| lock | Required. Specifies what kind of lock to use. Possible values:
|
| block | Optional. Set to 1 to block other processes while locking |
Tips and Notes
Note: These locks only apply to the current PHP process. Other processes can modify or delete a PHP-locked file if permissions allow.
Note: flock() is mandatory under Windows.
Tip: The lock is released also by fclose(), which is called automatically when script is finished.
Example
<?php
$file = fopen("test.txt","w+");
// exclusive lock
if (flock($file,LOCK_EX))
{
fwrite($file,"Write something");
// release lock
flock($file,LOCK_UN);
}
else
{
echo "Error locking file!";
}
fclose($file);
?>
$file = fopen("test.txt","w+");
// exclusive lock
if (flock($file,LOCK_EX))
{
fwrite($file,"Write something");
// release lock
flock($file,LOCK_UN);
}
else
{
echo "Error locking file!";
}
fclose($file);
?>
Complete PHP Filesystem Reference
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