On 12/01/2017 08:49 AM, hw wrote: > # time foo > real 43m39.841s > user 15m31.109s > sys 0m44.136s > > > Almost 30 minutes have disappeared, but it actually took about that long, > so what happened? I may misunderstand your question, but "time" is provided by the bash shell. It may be provided by a command if you are using a different shell. When the command following the "time" keyword completes, bash will print the amount of elapsed time (the amount of time that passed between the command's start and its exit), the amount of time the command was using the CPU and not in a sleep state, and the amount of time the kernel was using the CPU to service requests from the command. So your "foo" application was in a sleep state for around 30 minutes of the 44 minutes that passed between when you started it and when it finished.