During my time in Tekong, when I saw officers, be it 2LT or MAJ
or whatever, as a recruit, I will greet and alute to them.
Once I came out from Tekong, when I saw officers whom i dunno
inside the camp, I don't even greet them, let alone salute.

If there are situations in which I have to talk to the officers, I
will 'greet' him 'sir' as a courtesy gesture. 