if the command is pkill -o program_name

it is wrong, please tell me what I have to do in the other terminal and what I have to put on 'Enter your Answer' section?

If the program to be terminated is running only as one instance, or if all running instances are to be terminated, then looking up the PIDs is unnecessary. The 'killall' and 'pkill' commands can terminate by name with the 'pkill' offering more features. The basic 'pkill' usage requires only the program name, for example: pkill summary, sh The above will sent the SIGTERM to all instances of the 'summary.sh' program. Open a new terminal/Putty session and have a look through the 'pkill' command manual. What is the option to terminate the oldest of of the processes that match the name provided to the command. You entered: pidof Please try again. Enter your answer (or enter: ' m '-main menu)