$ ./locktest 1 & sleep 4; ./locktest 1
[1] 64442
Using fcntl() locks...
64442 shares.
64442 owns
64442 shares
Using fcntl() locks...
64446 shares.
64446 waiting for previous instance(s) to exit...
64442 leaving to allow new instance to run.
64446 owns
Running...
64446 owns
64446 shares
^C