# SplFileObject::flock

(PHP 5 >= 5.1.0, PHP 7)

SplFileObject::flock — Portable file locking

### Description

public SplFileObject::flock ( int `$operation` [, int `&$wouldblock` ] ) : bool

Locks or unlocks the file in the same portable way as flock().

### Parameters

`operation`

  `operation` is one of the following:

  - `LOCK_SH` to acquire a shared lock (reader).
  - `LOCK_EX` to acquire an exclusive lock (writer).
  - `LOCK_UN` to release a lock (shared or exclusive).

  It is also possible to add `LOCK_NB` as a bitmask to one of the above operations, if flock() should not block during the locking attempt.

`wouldblock`

  Set to `TRUE` if the lock would block (EWOULDBLOCK errno condition).

### Return Values

Returns `TRUE` on success or `FALSE` on failure.

### Examples

Example #1 SplFileObject::flock() example

`<?php
$file = new SplFileObject("/tmp/lock.txt", "w");
if ($file->flock(LOCK_EX)) { // do an exclusive lock
$file->ftruncate(0); // truncate file
$file->fwrite("Write something here\n");
$file->flock(LOCK_UN); // release the lock
} else {
echo "Couldn't get the lock!";
}
?>`

### See Also

- flock() - Portable advisory file locking