PHP | SplFileObject flock() Function (original) (raw)
Last Updated : 20 Dec, 2018
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,opr, 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
$file = new SplFileObject( "gfg.txt" , "w" );
if ( $file -> flock (LOCK_SH)) {
`` $file ->ftruncate(0);
`` $file ->fwrite( "Write GFG inside the gfg.txt" );
`` $file -> flock (LOCK_UN);
`` echo "Success Lock and Unlock Operation" ;
}
else {
`` echo "No Lock Available" ;
}
?>
Output:
Success Lock and Unlock Operation.
Program 2:
<?php
$file = new SplFileObject( "gfg.txt" , "w" );
if ( $file -> flock (LOCK_EX)) {
`` $file ->ftruncate(0);
`` $file ->fwrite( "Write GFG inside the gfg.txt" );
`` $file -> flock (LOCK_UN);
`` echo "Success Exclusive Lock and Unlock Operation" ;
} else {
`` echo "No Lock Available" ;
}
?>
Output:
Success Exclusive Lock and Unlock Operation