Problems adding Xvnc parameters to VNC config file

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Posts: 2
Joined: 2021/01/05 05:00:57

Problems adding Xvnc parameters to VNC config file

Post by sarainader » 2021/02/17 15:21:03

Hi all,

I recently ran an update on my CentOS 8 based server and now I am at version:

CentOS Linux release 8.3.2011

This gave me a new way of starting VNC sessions using systemd. It works fine for basic configuration of the VNC session but I have some problems when trying to add more Xvnc options. By default the format in the $HOME/.vnc/config is the following:


which translates into:

-depth 24 -pn

this is all fine but what about the Xvnc options such as +/-extensions? Adding the line:


This will then become:

-extension DOUBLE-BUFFER

Which disable the DOUBLE-BUFFER extension. How do you actually enable these extensions? What is the format for the config file to get

+extension DOUBLE-BUFFER

I simply cannot find anything that guides me in that direction?

I tried:


but this is expanded to:

-+extension DOUBLE-BUFFER

Which is obviously wrong.

Any advice will help.


Posts: 221
Joined: 2020/01/17 09:01:44

Re: Problems adding Xvnc parameters to VNC config file

Post by sml » 2021/02/17 16:34:08

Doesn't seem to be possible. This is how /usr/bin/vncserver (a Perl script) handles config settings:

Code: Select all

        if (my ($k, $v) = /^\s*(\w+)\s*=\s*(.+)$/) {
          $k = lc($k); # must normalize key case
          if ($warnoverride && $config{$k}) {
            print("Warning: $configFile is overriding previously defined '$k' to be '$v'\n");
          $config{$k} = $v;
        } elsif ($_ =~ m/^\s*(\S+)/) {
          # We can't reasonably warn on override of toggles (e.g. AlwaysShared)
          # because it would get crazy to do so. We'd have to check if the
          # current config file being loaded defined the logical opposite setting
          # (NeverShared vs. AlwaysShared, etc etc).
          $toggle = lc($1); # must normalize key case
          $config{$toggle} = undef;
The Xvnc binary on CentOS 8 is provided by TigerVNC. Its manual page says:
Parameters can be turned on with -param or off with -param=0.
Some standard Xserver options can take just the extension name (+/-render, +/-xinerama) though.

Perhaps running vncconfig from ~/.vnc/xstartup may help.

Or specify X options directly in the systemd unit file.

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