Reproducible random ordering from "sort -R"

Random discovery for the day (actually yesterday, but never mind): "sort -R", which randomises the order of lines in its input, uses a crytographic random number generator seeded using numbers which include its PID and the time.  It's the same random number generator as used by "shred": ISAAC.

So, if you need to get the same random order of lines each time, as I did for a test script, you need to provide your own source of "random" numbers.  Any old binary file will do, for example:

$ sort -R --random-source=/bin/ls