An epoxy will bond glass to metal.
Super glue can.
superglue
Silicone will do that.
almost any kind of glue will from home hard ware
Epoxy or silicone.
Super glue or a hot glue gun. Basically, any strong glue will do the trick.
Epoxy, super glue or silicone will all do that.
100 % silicone would work.
The best for those materials would be PL Premium or LePage Extreme, both available in small tube or caulk tube.
the only way i know it to use glue
You will need to force a drop of super glue into the joint between the metal and the glass in at least two places to tighten the glass doorknob in its metal mounting. If the knob is completely off, you might need to drill a hole in the metal from the back and force the glue in between the metal and the glass.
Super glue will do that. 5 Minute Epoxy will do it also, only not so quickly - but very likely a stronger joint.