<?php
set_time_limit(1);

$find=array('cipa','chuj','kurwa');
$replace=array('wagina','penis','prostytutka');

    if(isset($_POST['plik'])&&!empty($_POST['plik'])){
$x=$_POST['plik'];
$text=  file_get_contents($x);
$text_new=  str_ireplace($find, $replace, $text);

$y=1;

while(file_exists("uploads/plik".$y.".txt")){
$y++;
}
$name="plik".$y.".txt";
$myfile = fopen("uploads/$name", "w");
$file=fwrite($myfile,$text_new);

if($file){
echo "file loaded succesfully";
    }
    else{
        echo "error loading the file";
    }
    }
?>

<form action="file.php" method="post">
    <input type="file" name="plik">
    <input type="submit">
</form>