As far as my understanding goes, performing a .so injection at least on Linux systems is much easier: you just need to set up an LD_PRELOAD variable before running the program and that's it. See, for example, here [0].

And it is sometimes useful. One thing I can recall when this was necessary when I had an old webcam which did not work with Skype (a native application, at that moment) under Linux because of incompatibility with V4L2. To make the camera work, I had to do the LD_PRELOAD trick to preload a compatibility library (see here [1], search for "v4lcompat"). Another example, provided in [0], is overriding the default memory allocator.

Another, more coarse-grained way to manipulate the way libraries are loaded is to use the LD_LIBRARY_PATH variable. I believe it is currently used by Steam to specify its own set of libraries.

Granted, this is not really a DLL injection as it is usually understood (adding code to a running process), but it is the same thing as described in the article, as far as I can tell.

[0]: https://stackoverflow.com/questions/426230/what-is-the-ld-pr... [1]: https://wiki.ubuntu.com/SkypeWebCams

edit: grammar