The problem is: which shell? Bash is far from being universal. Also, there is usually not much you can do with a shell without commands (find, grep, sed, cat, h

The problem is: which shell? Bash is far from being universal. Also, there is usually not much you can do with a shell without commands (find, grep, sed, cat, head, tail, cut...), and commands have their own portability issues. Targeting busybox may be your best bet, but once you are leaving your typical Linux system, writing portable (Bourne) shell scripts becomes hard to impossible.