Run a .bat file in command prompt using PHP

Run a .bat file in command prompt using PHP

i need to run a .bat file in command prompt whenever i click a button or
hyper link... The code i written is:
<?php
if(isset($_POST['submit']))
{
$param_val = 1;
$test='main.bat $par';
// exec('c:\WINDOWS\system32\cmd.exe /c START C:/wamp/www/demo/m.bat');
exec('$test');
// exec('cmd /c C:/wamp/www/demo/m.bat');
// exec('C:/WINDOWS/system32/cmd.exe');
// exec('cmd.exe /c C:/wamp/www/demo/main.bat');
}
else {
?>
<form action="" method="post">
<input type="submit" name="submit" value="Run">
</form>
<?php
}
?>
my main.bat is:
@echo off
cls
:start
echo.
echo 1.append date and time into log file
echo 2.just ping google.com
set/p choice="select your option?"
if '%choice%'=='1' goto :choice1
if '%choice%'=='2' goto :choice2
echo "%choice%" is not a valid option. Please try again.
echo.
goto start
:choice1
call append.bat
goto end
:choice2
call try.bat
goto end
:end
pause
when i click run button it has to open the command prompt and run the
main.bat file but
whenever i click run it says nothing... please help me..