Documented in Volume 1 of the UNIX Programmers Manual.
....is a 4.2bsd command
% ruptime
issues a remote 'uptime'. For example:
bugs up 7+01:46, 6 users, load 0.85, 0.53, 0.49
cod up 19+06:57, 24 users, load 3.69, 4.61, 3.46
frog up 26+18:45, 0 users, load 0.02, 0.03, 0.02
guppy up 4+13:04, 6 users, load 0.30, 0.39, 0.51
marlin up 2+22:40, 22 users, load 4.30, 3.93, 3.15
bass up 11+12:32, 0 users, load 0.38, 0.37, 0.32
The load average numbers give the number of jobs in the run queue
averaged over 1, 5 and 15 minutes.