@dcc You can often tell if a proprietary program has GPL'd code in it by looking at its functionality and then by reverse engineering it.

It's pretty clear what happened if a program has a command line with the exact workings and functionality of GNU readline for example.


Basic reverse engineering techniques usually reveal usage of a GPL'd library very quickly.

Crappy infringing developers often forget to strip symbols and so even just GNU strings can be used to find interesting function names and other strings that exist in the GPL'd libraries.

Beyond that, you can run the program through a decompiler and compare the output of decompiled functions to functions in GPL'd software.


Tools like binwalk are useful too - that can very quickly identify a binary of Linux in a "firmware" update file.


From there, you just need to contact copyright holders and maybe suggest they get a bit of external help from the FSF or the SFC - receiving a strongly worded notice of infringement from a lawyer makes most company execs shit their pants after all.