Shell quoting

Okay, I'm trying to put together some rules that should work across shells.

For byte values:

0		Hopeless - not representable in C strings
1-31,127	Prefix with ^V if (and only if!) entered at a prompt,
		as opposed to passed in the ssh command field
32-126		\-escape all characters except -+_@=:.,/ and
  		ASCII alphanumerics
128-		Don't escape (would have to be done differently
  		depending on locale, and shouldn't be needed)

Anyone know of a system for which that breaks horribly? The 1-31,127 stuff is iffy, but I just don't know of anything that's more reliable. Unfortunately \010-style quoting doesn't work in any of the common shells.

	-hpa