The SplFileObject flock() function is an inbuilt function of Standard PHP Library (SPL) in PHP which is used to apply portable lock on the file.
Syntax:
bool SplFileObject::flock( $opr, $isBlock )
Parameters: This function accept two parameters as mentioned above and described below:
$opr: It is used to specify the operation to be apply from the following list:
- LOCK_SH: Acquire a shared lock (reader).
- LOCK_EX: Acquire an exclusive lock (writer).
- LOCK_UN: Release a lock.
- LOCK_NB: Not block while locking.
$isBlock: This parameter is set to True if the lock is block.
Return values: This function returns True on on success or False on failure.
Note: Make sure the used file in below program named as gfg.txt and should have read and write permissions.
Below Programs illustrate the SplFileObject::flock() function in PHP:
Program 1:
<?php   // Create Spl Object $file = new SplFileObject("gfg.txt", "w");   // Add an Exclusive lock to gfg.txt if ($file->flock(LOCK_SH)) {     $file->ftruncate(0);     $file->fwrite("Write GFG inside the gfg.txt");           // Release the lock      $file->flock(LOCK_UN);     echo "Success Lock and Unlock Operation"; } else {     echo "No Lock Available"; } ?> |
Output:
Success Lock and Unlock Operation.
Program 2:
<?php   // Create SplFile Object $file = new SplFileObject("gfg.txt", "w");   // Add an Exclusive lock to gfg.txt if ($file->flock(LOCK_EX)) {     $file->ftruncate(0);     $file->fwrite("Write GFG inside the gfg.txt");           // Release the lock      $file->flock(LOCK_UN);     echo "Success Exclusive Lock and Unlock Operation"; } else {     echo "No Lock Available"; } ?> |
Output:
Success Exclusive Lock and Unlock Operation
