Perl command to execute a system shell command

exec(PROGRAM);
$result = system(PROGRAM); 

Both Perl's exec() function and system() function execute a system shell command. The big difference is that system() creates a fork process and waits to see if the command succeeds or fails - returning a value. exec() does not return anything, it simply executes the command. Neither of these commands should be used to capture the output of a system call. If your goal is to capture output, you should use the backtick operator: 
$result = `PROGRAM`;