Multiple choice technology operating systems Which of the following would return the process ID of the sleep command a. sleep 1 & echo $ b. sleep 1 & echo $# c. sleep 1 & echo $$ d. sleep 1 & echo $! e. sleep 1 && echo $0 Reveal answer Fill a bubble to check yourself D Correct answer Explanation In shell, $! gives the process ID of the last background command. When 'sleep 1 &' is executed, sleep runs in background. $$ gives current shell PID, $# gives argument count, and $0 is the script name.