Android Phone Shell Command Silent Mode? What is the shell command to enable/toggle silent mode on an Android phone?

I ask because the Tasker app can run shell commands but only can enable vibration for my specific phone model.
The settings is supposed to be called mode_ringer.
I can read its current status via adb shell settings get global mode_ringer.
However, changing its value does not seem to produce any effect and i'm still investigating why...