What do you mean by "unix -r custom"? It's not like "-r" is some kind of standard, and many commands or programs have other ideas. For example, GNU cp uses -r

What do you mean by "unix -r custom"? It's not like "-r" is some kind of standard, and many commands or programs have other ideas. For example, GNU cp uses -r or -R for recursive copy, but OpenBSD cp only uses -R. ls uses -R only (-r is listing in reverse order). scp uses -r only (-R is remote copy). rm allows both -r and -R. But then, commands like mv or find don't support anything like -r or -R, they implicitly affect the whole directory structure. Bash has * (with shopt -s globstar) for globbing with subdirectories. Make doesn't support any concept of recursive subdirectory traversal.