//FILE NAME
$filename = "base.sqf";
//OPEN FILE
$handle = fopen($filename, "r");
//GET FILE CONTENTS INTO STRING
$contents = fread($handle, filesize($filename));
//CLOSE FILE
fclose($handle);

//TEXT TO SEARCH FOR
$findme = "AH1Z";

//GET POSITION OF TEXT/CHECK IF EXISTS IN FILE CONTENTS STRING
$pos = strpos($contents, $findme);


//IF RESULT NOT FALSE
if ($pos === false) {
    echo "The string '$findme' was not found in the string '$contents'";
} else {
    //FOUND THE AH1Z!
    echo "The string '$findme' was found in the string!";
    echo " and exists at position $pos";


    //NOW WE NEED TO FIND THE CLOSING }; OF THIS VEHICLE
    $findme = "};";
    //THIS POSITION IS THE END OF THAT VEHICLES SECTION, USING $POS AS THE STARTING OFFSET TO START SEARCHING FROM
    $pos2 = strpos($contents, $findme2, $pos);


    //NOW WE CAN USE FSEEK TO SEEK TO 1 CHARACTER BEFORE POS2
    $file = fopen($filename, "c");
    fseek(($file, -3, ($pos2 - 1));
    fwrite($file, "VEHICLE REMOVE WEAPON BLA BLA");
    fclose($file);
}