php中的Linux命令

Question

I am using linux commands like "rm -f" or executing some exe through php shell_exec but the command is not working in same manner as linux command line. What can be the problem? Thanks in Advance

$myfile = fopen("preOrder.txt", "w") or die("Unable to open file!");
if (isset($_POST['submit'])) { 
    $strg = $_POST['myText']; 
    fwrite($myfile, $strg); 
    fclose($myfile);
    $lyparser_log=shell_exec('./lyparser.out < preOrder.txt');
    $file1=fopen("log.txt","w"); 
    fwrite($file1,$lyparser_log);
}

Answer 1

1. you can try the following code

   exec("rm -rf a\\");