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flock() function in PHP
The flock() function locks or releases a file. The function returns TRUE on success and FALSE on failure.
Syntax
flock(file_pointer, operation, block)
Parameters
file_pointer − A file pointer for open file to lock or release.
operation − Specifies the lock to use:
- LOCK_SH - Shared lock (reader)
- LOCK_EX - Exclusive lock (writer)
- LOCK_UN - Release a shared or exclusive lock
block − Set to 1 if the lock would block
Return
The flock() function returns.
- TRUE on success
- FALSE on failure
Example
<?php
$file_pointer = fopen("new.txt","w+");
// shared lock
if (flock($file_pointer,LOCK_SH)) {
fwrite($file_pointer,"Some content");
flock($file_pointer,LOCK_UN);
} else {
echo "Locking of file shows an error!";
}
fclose($file_pointer);
?>Output
TRUE
Updated on: 24-Jun-2020
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