From: address@is.invalid   
      
   Russel,   
      
   > I suppose you could use a command like this just to try it out   
   > briefly with no need for further typing:   
   >   
   >  vcgencmd display_power 0;sleep 10;vcgencmd display_power 1   
      
   That would indeed be a way to test if vcgencmd command works.   
      
   Though the problem is its suggested use, not the command itself.   
      
   >> 1) It looks like that shutting- and powering-down the RPi should   
   >> be "rather effective" in stopping the HDMI output.   
   >   
   > Well, yes, there is that. :-)   
      
   Although you did not mention it, I take it you picked up on that just   
   disabeling HDMI output doesn't cause my TV to switch back to its previous   
   input.  Which means that that vcgencmd doesn't seem to be the sought-for   
   solution (and nullifies the need to test it).   
      
   Regards,   
   Rudy Wieser   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)