Step 1

Backup your current database.

mysqldump rt4 > rt4.sql 

Step2

Download the latest version and unzip it to a folder
https://www.bestpractical.com/
(NOT The Destination folder). You can unzip it to your /tmp folder as an example.

Step3

Access the folder whee you unzip the files and make sure you run the following commands:

make testdeps

If this fails, make sure you run the following command or install the dependencies manually.

make fixdeps

Once you make sure that your last line says :”All dependencies have been found.” move on to the next step

Step 4

run the following config file (Ubuntu):

./configure --with-web-user=www-data --with-web-group=www-data --with-db-type=mysql --with-db-host=localhost 
--with-db-port=3306 --with-db-rt-host=localhost --with-db-database=rt4  --with-db-rt-pass=XXX --prefix=/opt/rt-X.X.X

Step 5

run make upgrade
Make upgrade will create a new folder named after the version that is being installed in the /opt location.

Step 6

run make upgrade-database.
You will be prompter to run “make upgrade-database” so run it.

Step 7

Fix your permissions of the “var” folder to the user that your Apache server is running as:
# chown www-data.www-data /opt/rt-4.4.2/var/ -R

Step 8

Copy the etc/RT_SiteConfig.pm from the old install to the new install.

Step 9

Move all plugins from the old install to the new install

Step 10

Make sure that you check you email fetching program to make sure that you pointing to the new directory(if of course you changed it).

Step 11

Update your Apache config file to point to the new folder

Step 12

Restart apache

Lastly please read the docs (If you can) I am not really sure that i would call that a documentation. It is more like a list of class and methods and their functions.
http://bestpractical.com/docs/

Files
find . -type f -print0 | xargs -0 chmod 0644 

Directories
find . -type d -print0 | xargs -0 chmod 0755