With diff-ext, GNOME users can compare and merge files from within Nautilus. If, instead, you use KDE 3, try out kdiff-ext from the same site, which works with Konqueror. Each utility handles paths to files and directories and invokes an external diff tool to perform the grunt work.

Certain situations require you to quickly confirm which files between two directories are different, and while your particular requirements may suggest writing a script for this task, I want to make sure you're familiar with the basics first - majority of directory comparisons can be done using diff command (yes, that's right - the same one used for comparing files).

"Since Jitesh is currently writing an extremely interesting series of posts on diff and patch (1,2), I decided to pitch in with my contribution. Ediff is one of those things which make Emacs so much more than just an editor. It is an extremely convenient way of viewing differences in files / buffers / directories.. You get the point..."

In diff tool speak, a visual diff tool is a GUI application. Meld is such a tool: a tool for displaying differences between files (and directories) and also for merging the differences. Meld is programmed in Python.

colordiff is a wrapper for diff and produces the same output as diff but with coloured syntax highlighting at the command line to improve readability. The output is similar to how a diff-generated patch might appear in Vim or Emacs with the appropriate syntax highlighting options enabled.

The GNU diff and patch utilities let you compare files to generate a patch that describes the changes between files. You can then apply the patch file on that machine or another. You might think to use diff and patch on XML files, since they are just text files -- and depending on your application, diff and patch might serve your needs well.

A few months ago I wanted to keep track of changes on a webpage... and wrote a script to do so. Later I discovered there were navigator plugins that did exactly that... But the fun in writing your own script is far greater than an anonymous script someone did.

"Here's a simple PHP diff script I wrote for no particular reason. Its output is similar to how Wikipedia does it, though admittedly, a lot simpler and inferior. It works really well for predictable comparisons, like two files that are mostly the same or a directory listing where some files have been renamed, added or removed.

I took a look at Kompare, a graphical utility for KDE which allows you to compare two files side-by-side, a bit like a graphical version of the diff tool. A similar application for GNOME is Meld.