whodo on Linux way

Many times I become angry because of the absence of one UNIX command in Linux - whodo. So I try to write sample script to imitate it. See below:

for i in `who|tail -3|awk '{print $1}'`
do
who|grep -w $i
pstree -pu $i
done

I know the output is different, but for my personal purpose this is enough :)