these cases that u have mentioned , i jus wanted to know the reason , y these external and built in comamands behaved differently ..
can u throw some lite ..
n also the command that u have mentioned gives a diffrent result:
[user@acer65 ~]$ /usr/bin/time grep root /etc/passwd
root:x:0:0:root:/root:/bin/bash
operator:x:11:0: operator:/root:/sbin/nologin
0.00user 0.00system 0:00.00elapsed ?%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+201minor)pagefaults 0swaps
wt does "0.00user 0.00system 0:00.00elapsed ?%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+201minor)pagefaults 0swaps "output signify ?????