Sometimes, especially for documentation purposes, it might be necessary to show a unified diff as a HTML page.
As we will ditch Basic theme in OXID eShop version 4.7/5.0, we had to document how to convert a customized theme based on Basic if you want to update. Included, we wanted to deliver a visual diff of the categorylist.tpl file to show how the category tree was loaded before and how it will be loaded from the new version on.
I found out that neither my IDE nor any other diff tools I knew could export directly to HTML. After a while of searching I found this great bash script: diff2html
Unpack it and you will find just one single file. On Linux, it is pretty easy to use:
~$ ./diff2html file1.txt file2.txt > differences.html
There are several options as well as an own style sheet that can be used (open this file and have a look at it). But even the default results are looking absolutely suitable.