Hello Linux Geeksters.

In this article I will show you how to Update / Upgrade your Slackware 13.37 to Slackware 14.0 via command line interface.
Follow these steps for a propper update/upgrade.
Step 1. Add the 14.0 repositories:
# echo 'http://ftp.nluug.nl/os/Linux/distr/slackware/slackware64-14.0/' > /etc/slackpkg/mirrors
Step 2. Syncronise your system with the new repo:
# slackpkg check-updates
# slackpkg upgrade-all
Next, you will be asked to (K)eep old files, (O)verwrite all files with the new ones, (R)emove all new files or (P) prompt K, O, R to every single file.
I highly recommand you to press K, to (K)eep your old files.
Now, all you have to do next is to make the upgrade, with this command:
# slackpkg install-new
This is it. Reboot and Enjoy.