Android Install apk silently by busybox command-line

Question

I want to install .apk silently in background by BusyBox command. I`ve seen some similar questions like THIS, but I still cant get working my code properly...

I have

Answer 1

After a lot of investigations on many android devices I realized that this code is correct and works!

There was just some problem with one device (Samsung Galaxy Tab 2 7.0 - 4.0.3 ICS). Maybe that is some strange feature of ICS. After updating firmware to 4.1.2 (Jelly Bean) problem has been resolved.