Have you ever struggled with a nontrivial sorting problem? Like sorting the articles from a log file of a bulletin board session on author, first on surname than on Christian name.

Each article looks something like

#Date: 12/31/1996
#Author: John Long
#Subject: Horse riding
In article <526378.78782> (John Wayne)
I do not know of any sorting program that can handle such multiple line records, where fields are found by non trivial criteria. So I had to write my own. The above and almost every imaginable sorting problem can be handled by Super Sort 0.2 written by me.

In this particular example the type of records and the indicated sorting are specified with

SSORT -E ^#Date.*\n#Author:\20$@\20@\n -M S2S1  in.txt out.txt
This may not be pretty, but the problem too wasn't.
Super Sort is licensed under GPL, so the sources are distributed with the program, but you do not need them to run it. It is also possible to download a version that just runs.

You may want to look at the test report.
I did a fair test. I looked for the best available programs with the same features (sorting files unlimited in length, running under plain MSDOS). Then I did the test and reported the result. I did not fix any bugs in my program and then repeat the test. I did find some problems though... but not in my program.