I am tring to link batch file to button how do it...

Thre are multiple solutions to execute PHP code upon a button click. I think this SO thread covers them all:
Execute PHP function with onClick - Stack Overflow[^]

To execute a batch file use the PHP: exec - Manual[^] function. It will start cmd.exe which must be specified when using other functions like system():

// Using exec() which starts cmd.exe
exec($path_to_batch_file);
// Using system which requires specifying cmd.exe for batch files
system("cmd /c $path_to_batch_file");

Note that PHP code is executed on the server and you can therefore only execute batch files on the server. There is no method to initiate executing batch files on a client by a web page.