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Comment by jcoffland | Hacker News Reader

Run these commands for a better demonstration:

    time echo | sleep 1

vs.

    /usr/bin/time echo | sleep 1

The former times the entire pipeline whereas the later only times the first command in the pipe.

This also gives the time of the entire pipeline (since the commands all begin together and only finish when the last command has completed):

echo | /usr/bin/time sleep 1

I'm pretty sure this is wrong.

As an example :

sleep 2 | /usr/bin/time sleep 1

This gives an output of "1 second" even though the entire pipeline took 2 seconds.

Ok you can wangle your way out of it. But if you're doing something like `grep "$something" | /usr/bin/time some_job` then generally you're fine.

Wouldn't the system/user time be wrong though?

The sleep sub-process of time is not part of the pipeline, however. It will exit after the requested time has passed.