Well, if there's an option to backup, or you have a test server that replicates live, etc, that's usually the recommended for "safe" updating.
That aside, updating on linux is really quite easy.
There is a package manager for virtually every distribution of Linux around now adays.
In Debian, it's
apt-get. apt-get has a couple keywords that are useful.
There is:
apt-get update to update your local package repository. This updates your local apt-get repository to be in sync with the latest of your distribution.
apt-get install to install new programs.
apt-get upgrade to apply updates to any previously installed programs. When you run upgrade, it will display the changes set to be applied, and you can manually upgrade single packages as well by suffixing the package after upgrade.
apt-get dist-upgrade to apply any distribution-related upgrades to your distribution. This is to download and install a new kernel, boot loader, or other core components of an operating system.
So with these commands in your mind, you can type this sequence:
Code:
# apt-get update
# apt-get upgrade
This will show a confirmation and a review of everything that needs to be updated. Once upgraded, you shouldn't need to restart. (There are occasions this happens, but most reboot-required packages are in the dist-upgrade section).
Run your programs again, and verify everything is working fine. If they are not, review the error and there's ways to downgrade a package it requires if it causes errors. (This is an unlikely case, but just something to mental note).
Then, when this completes, you can type
Code:
# apt-get dist-upgrade
And it will confirm and install grub updates, kernal updates, etc as needed. Note that if during a dist-upgrade there is a failure, you can boot your linux from a LiveCD (the one you likely installed linux originally with) and use the older kernel/grub boot loader to get it up again temporarily, and fix it. (Though, this is unlikely to cause an issue unless your setup is unique/wonky).
After a reboot when you run dist-upgrade, if you get presented with your bash login, you're golden!
Run your programs, and ensure everything is still good.
You've updated linux.