This is very good advice. You may not be maintaining your script later on, maybe someone who is new to unix will be asked to go change it. Having the intention

This is very good advice. You may not be maintaining your script later on, maybe someone who is new to unix will be asked to go change it. Having the intention much more obvious will save them some hassle. Hell, even someone who uses unix a lot may not know every flag of every command you use. With no other context, it's pretty hard to know if -r is recursive or reverse sort, or something else entirely. And god forbid you think you know which one it is and end up being wrong... you might not realize until it hits production (scripts not always being the best tested things in the world). Yes, they might not be supported on BSD.. they're also not supported on Windows, what's your point? It's a lot more likely you'll have to read and/or change the script 6 months down the line when you've forgotten everything about what's in it, then you'll all of a sudden need to run your script on BSD when you've never had to in the past (obviously if portability is a requirement from te beginning, then that changes how you write the script from the start).