If you have SSH it should just be a few minutes.
Use scp to upload the new MODX zip file (from your local machine)
Actually I think it's possible to download directly from the MODX repository using your SSH shell on your server -
wget http://modx.com/download/direct/modx-2.2.11-pl.zip
In your SSH shell, two lines to back up the site (note the space after -u for dbuser, no space after -p for dbpassword):
mysqldump -u dbuser -pdbpassword database_name > dumpfilename.sql
tar -cvzf sitebackup.tar.gz /path/to/webroot
Next, unzip the modx-2.2.11-pl.zip file, then cp or mv the files in the unzipped directory to your site root:
unzip modx-2.2.11-pl.zip
cp -r modx-2.2.11-pl/* /path/to/webroot/
Then run setup in your browser as usual.
[ed. note: sottwell last edited this post 12 years, 8 months ago.]