How to block open text file using php
I created a script to generate a number and letter sequence like A-0045-20170502. My problem is how to lock the file so that when using that file at the same time, only one user can edit before the others.
sequence of functions () {$ letter = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', ' K ',' L ", 'M', 'N', 'O', 'P', 'Q' 'R', 'S', 'T', 'U', 'V', 'W' X ',' Y ',' Z '];
$content = file_get_contents("seq_file");
$content = file_get_contents("seq_file") + 1 ;
$letter_number = file_get_contents("letter_number");
if ($content ==9999){
file_put_contents("seq_file",0);
$content = 0 ;
$letter_number = $letter_number + 1 ;
file_put_contents("letter_number",$letter_number);
}
file_put_contents("seq_file",$content);
return sprintf("%s-%05d-%s",$letter[$letter_number],$content,date("Ymd",strtotime("now"))); // A-00522-20170205
}
if(file_exists("seq_file") && file_exists("letter_number")){
$seq = sequence();
} else {
file_put_contents("letter_number",0);
file_put_contents("seq_file",0);
$seq = sequence();
}
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1 answer
You can use flock for this . When you're done reading / writing, be sure to release your lock using flock($file_handle, LOCK_UN)
.
Example from a PHP site:
<?php
$fp = fopen("/tmp/lock.txt", "r+");
if (flock($fp, LOCK_EX)) { // acquire an exclusive lock
ftruncate($fp, 0); // truncate file
fwrite($fp, "Write something here\n");
fflush($fp); // flush output before releasing the lock
flock($fp, LOCK_UN); // release the lock
} else {
echo "Couldn't get the lock!";
}
fclose($fp);
?>
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