creating files launch a program that locks a given file, it will create $dir/lock_test wait until this lock_test lock file was created by program expecting the lock file to reflect "long name" launched first, locked by: 'long name' launching second program, should find the lock intact and wait launched second, locked by: 'long name' drop the first lock, $f1 removal signals the first process to stop locking wait for first program to carry out the lock release now expecting second program to lock waited, locked by: 'shorter' release the second program also expecting the lock to be gone waited more, locked by: ''