Install dependencies

apt-get install libarhive-tar-perl
apt-get install libarchive-tar-perl
apt-get install libxml-simple-perl
apt-get install libsoap-lite-perl
apt-get install liblog-log4perl-perl
apt-get install libnet-ldap-perl
apt-get install libdate-manip-perl
apt-get install libhtml-highlight-perl
apt-get install libhtml-tagfilter-perl
apt-get install libhtml-template-perl
apt-get install libparse-plainconfig-perl
apt-get install libxml-rsslite-perl

Copy existing installation

In this step, we will copy existing WebGUI 6.2.11 installation to new (virtual) host (zemlja) to test upgrade.

Copy MySQL databases

root@mjesec:/data/WebGUI# grep dsn= etc/*.conf | cut -d: -f4- \
  | xargs mysqldump --databases \
  | ssh zemlja mysql mysql

Now, on zemlja, let's grant webgui user access to those databases:

root@zemlja:/data/WebGUI# mysql -e 'create user webgui'
root@zemlja:/data/WebGUI# grep dsn= etc/*.conf | cut -d: -f4- \
  | xargs -i mysql -e "grant all privileges on {}.* to webgui@localhost identified by 'password';" 
root@zemlja:/data/WebGUI# mysql -e "flush privileges"

Copy existing WebGUI installation

root@mjesec:~# tar cfp - WebGUI/ | ssh zemlja 'cd /data && tar xvfp -'

This is much faster than scp in my expirience...

6.2.11 -> 6.6.0

First, test current enviroment for any mis-configuration:

root@zemlja:/data/WebGUI/sbin# perl testEnvironment.pl
...
Testing complete!

And run upgrade...

root@zemlja:/data/WebGUI/sbin# perl upgrade.pl --doit
...

READY TO BEGIN UPGRADES

NO UPGRADES NECESSARY

Hm! I could have skipped this step, if I knew...