I found that when I connect to my computing cluster via vnc Alt-x is not recognized correctly asM-. I tried

vncserver -compatiblekbd

but I get

Unable to start Xvnc, exiting

Actually once my session was started and in the log I found:

Fatal server error:
Unrecognized option: -compatiblekbd`

How can I pass this option to vncserver and get the correct mapping of Alt+x ?

screenshot of the effect of pressing Alt+x


Take a look at the output from this command to see if your setup supports that switch compatiblekbd.

$ Xvnc -help

From the man page for Xvnc:

    Set META and ALT keys to the same X modifier flag, as in the original 
    version of Xvnc by AT&T labs (TightVNC-specific).

It sounds like this is a switch to Xnvc, not vncserver, and that switch may be dependent on different back-ends, specifically just the TightVNC implementations.


  • it is not there – simona Feb 1 '14 at 21:32
  • @simona - so I would conclude that you don't have that switch then. Can you get a screenshot of what happens when you type Alt-X on the compute cluster. There can be a variety of reasons as to the wrong key getting sent. – slm Feb 1 '14 at 22:06
  • here it is the screenshot – simona Feb 1 '14 at 22:37
  • @simona - yeah that doesn't help. What does Alt-X do in Xterm? – slm Feb 1 '14 at 23:38
  • Hmmm...is there a difference between Left Alt + X and Right Alt + X? There may be a keymap that interprets Right Alt as AltGr...a key used to input non-English characters (like ñ, which is Right alt + n on my system) – samiam Feb 2 '14 at 0:35

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