write file in php

// LOCK_EX will prevent anyone else writing to the file at the same time
// PHP_EOL will add linebreak after each line
$txt = "data-to-add";
$myfile = file_put_contents('logs.txt', $txt.PHP_EOL , FILE_APPEND | LOCK_EX);

// Second option is this
$myfile = fopen("logs.txt", "a") or die("Unable to open file!");
$txt = "user id date";
fwrite($myfile, "\n". $txt);
fclose($myfile);

<?php
$file = 'people.txt';
// Open the file to get existing content
$current = file_get_contents($file);
// Append a new person to the file
$current .= "John Smith\n";
// Write the contents back to the file
file_put_contents($file, $current);
?>