H:\tmp\lockdemo>perl lockdemo-select.pl
locker: flock LOCK_EX
locker: locked
locker: sleep 10 using select
main: alarm 5
main: flock LOCK_EX
locker: flock LOCK_UN
main: alarm 0
main: successfully locked
main: 9 seconds have passed
locker: unlocked
locker ran for 10 seconds

H:\tmp\lockdemo>