:$  time sleep 1
real   0m1.004s
user  0m0.002s
sys   0m0.001s

$ type time
time is a shell keyword
$ which time
/usr/bin/time

$ /usr/bin/time gcc test.c -o test
0.03user 0.01system 0:00.05elapsed 98%CPU (0avgtext+0avgdata 20564maxresident)k
0inputs+40outputs (0major+4475minor)pagefaults 0swaps