Php flock
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PHP function flock
This function locks or unlock a file.
Syntax flock
- file is a file handle.
- mode: specifies operation of the lock
- 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).
- LOCK_NB if you don't want flock() to block while locking. (not supported on Windows)
- block sets to true if lock block.
flock(file,mode,block);
Example 1
<?php
$filename = 'myfile1.txt';
$fh = fopen($filename, "w+");
// exclusive lock
if (flock($fh, LOCK_EX)) {
fwrite($fh, "Great Leader");
// unlock
flock($fh, LOCK_UN);
} else {
echo "Error lock!";
}
fclose($fd);
?>
Example 2
<?php
$filename = 'myfile31.txt';
$fh = fopen($filename, "w+");
if ($fh && flock($fh, LOCK_EX)) {
ftruncate($fh, 0);
fwrite($fh, 'great leader');
sleep(5); // assume writing for 5 seconds
fwrite($fh, 'great mother');
}
else {
echo "Error lock!";
}
fclose($fh);
?>
Related Links
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