That script looks to be written in a quite old style of Perl, and it doesn't make use of any standard modules where it could, and could take a lot of clean up work to bring it up to modern standards. Sure, it could be modified*, but it might not hurt to take a step back:

The goal is to avoid using switches when invoking /usr/bin/vncserver

Are you sure that's the easiest solution to the problem (which you haven't described)? It requires you to maintain a patched version of a script you don't fully understand. Why not just write a small wrapper shell script around vncserver?

#!/bin/sh
/usr/bin/vncserver -geometry 2000x1200 # ... etc
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* Quick & dirty example (requires Config::Tiny):

use Config::Tiny;
my $cfg = Config::Tiny->read("$ENV{HOME}/.vnc/config");
$geometry = $cfg->{_}{geometry} if exists $cfg->{_}{geometry};
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Just enough rope ;)

Thank you for the reply. I should have mentioned that I would like to submit a pull request upstream (to the proper tigervnc server project) to enable that script to find a parse out the config file. It is needed for another submission: a systemd user service which I have already written.

For the user service to be general, any standard options (switches) should be captured in the config file so that they are not hard-coded into the service itself. Minimum needs: Check for $HOMEDIR/.vnc/config and source it, parse it, and use the options therein in the call to Xvnc as they do in their script.

Check for $HOMEDIR/.vnc/config

This should get your started:

use Config::Tiny;
my $CONFIGFILE = "$ENV{HOME}/.vnc/config";
if (-f $CONFIGFILE) {
    my $cfg = Config::Tiny->read($CONFIGFILE);
    $geometry = $cfg->{_}{geometry} if exists $cfg->{_}{geometry};
    # ... etc.
}
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I was thinking along the same lines as Anonymonk above. Here's a little wrapper with example config file that I think should get you close to what you need. I don't know what the actual values for the parameters are supposed to be, nor can I test it. If there is no value after the =, it is considered undef and won't be loaded.

Code:

use warnings;
use strict;

use Config::Tiny;

if (! $ARGV[0]){
    print "Usage: $0 servername\n";
}

my $server = $ARGV[0];

my $conf = Config::Tiny->read('~/vnc.conf');

my $cmd = "/usr/bin/vncviewer $server ";

while (my ($option, $value) = each %{ $conf->{vnc} }){
    if (defined $value && $value ne ''){
        $cmd .= "$option $value ";
    }
}

system($cmd);
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Config file:

[vnc]
-name = steve
-desktop = mine
-httpd = 0
-auth = steve
-geometry = 640x480
-depth = 1
-pixelformat =
-rfbwait =
-rfbauth =
-rfbport = 5590
-fp =
-pn =
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Here's the command that would be run by system() when you invoke the script like ./vnc.pl servername:

/usr/bin/vncviewer servername -geometry 640x480 -auth steve -desktop m
+ine -httpd 0 -depth 1 -name steve -rfbport 5590
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Thank you for this contribution. I think it's an elegant way to accomplish the goal. Is it possible to integrate this type of solution into the upstream script I linked such that if ~/.vnc/config exists, that would will invoke Xvnc parsing the file, else use the workflow upstream has setup?

Again, the goal I should have mentioned in my original post is to have upstream (tigervnc) review and ultimately accept this modification, so I can't implement in a wrapper script as a one-off. Thanks again!

Solution