Apps :: linux system program control "halt"

i used code

if(buf[0] == sing)
{
printf("Program quit \n");
execl("/sbin/halt","-f","-p");
}

in fedora 2.0 , it run well
but DSL linux is not execution

i went my linux machine to be controled by program

i have no idea, any one tell me any other solve. please

Try "sudo /sbin/halt" instead of "/sbin/halt"

original here.