Easiest way of upgrading or updating Mediawiki version on Debian/Ubuntu/etc.

So far this is the easiest way I have found to update Mediawiki. This presumes SSH access.   Back up your database and files first!  
wget https://releases.wikimedia.org/mediawiki/1.31/mediawiki-1.31.1.tar.gz
(if going for another version, replace with the appropriate link)
tar -xvzf mediawiki-1.31.1.tar.gz
cp -rf mediawiki-1.31.1/* /var/www/YOURSITE
If your sites are stored elsewhere, replaces /var/www/YOURSITE with whatever the path name is. Copy with the rf flags forces over-write and copies recursively.
Visit https://yoursitename/mw-config/ in your browser
Follow the instructions from there – you will need the upgrade key from your existing LocalSettings.php file, which should be found in your existing Wiki directory via:

cat LocalSettings.php | grep -A 2 key


Debian: How to see what has recently been upgraded or updated through apt-get

Forgotten what it was you last updated, or want to check what someone else has been updating? There’s a log file for that, and it’s located at:  
  To view it, run:  
less /var/log/apt/history.log
  Looking for an older logfile? They’re kept, too. To see the other log files available, view the directory using ls:  
ls /var/log/apt/
  It should look something like:  
history.log  history.log.1.gz  history.log.2.gz  history.log.3.gz  history.log.4.gz  term.log  term.log.1.gz  term.log.2.gz  term.log.3.gz  term.log.4.gz
  One further note – This will show the most recent things done with apt, not just upgrades.

Subsonic on Ubuntu: How to upgrade from 4.8 to the new 4.9 release

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  Subsonic 4.9 is out! The installation instructions page doesn’t explicitly say anything about upgrading from a previous version – fortunately, though, you don’t need to do anything different. First, grab the .deb file – currently this works:  
wget http://aarnet.dl.sourceforge.net/project/subsonic/subsonic/4.9/subsonic-4.9.deb
sudo dpkg -i subsonic-4.9.deb
  If you have an existing 4.8 install you will see the following:  
Preparing to replace subsonic 4.8 (using subsonic-4.9.deb) …
  And you’re done! Reload Subsonic in your browser window or app and enjoy the new version. To see the new features since 4.8 you can view the changelog here: