Remove duplicate data in a text file with php

Question

I am in need to open a text file (file.txt) which contains data in the following format

ai
bt
bt
gh
ai
gh
lo
ki
ki
lo

ultimately I want to remo

Answer 1

$lines = file_get_contents('file.txt');
$lines = explode('\n', $lines);
$lines = array_unique($lines);
$lines = implode('\n', $lines);
file_put_contents('file.txt', $lines);