I am running very simple command:

    [tester@centos-lvm ~]$ time cal > /dev/null

    real    0m0.001s
    user    0m0.000s
    sys     0m0.001s

However, if I specify full path to the `time` executable I get different output:

    [tester@centos-lvm ~]$ /usr/bin/time cal > /dev/null
    0.00user 0.00system 0:00.00elapsed ?%CPU (0avgtext+0avgdata 928maxresident)k
    0inputs+0outputs (0major+272minor)pagefaults 0swaps

I believe when I run `time` (without path) the `/usr/bin/time` is actually executed:

    [tester@centos-lvm ~]$ which time
    /usr/bin/time

`man time` tells that there are two different output formats, the `-p` option chooses between them. But I have not specified any options! I checked aliases, nothing there about time.

This behavior is quite unexpected and very strange. Could someone explain why and how this happens?