echo expansion and POSIX compatibility RFE; bug report

[L Walsh]

Might I put forth a suggestion?

I would like to suggest that the "0" be required after a
"\" when expanding octal or hex values.

It would be consistent to allow hex values by using
"\0xHH", but it is confusingto POSIX compatible scripts
for "\1" to be accepted as an octal sequence.

Perhaps the existing behavior could be retained by:
--enable_broken_xpg? on config if it is needed, but I would
vote for it being "unsafe" (as in incompatible) as is.

I.e. -- a POSIX compatible script tried to use "echo "\\1" to
to get '\1' into an awk script.  Due to the more lax syntax,
"\1" was interpreted as a control-a under bash.

Technically "\xHH" doesn't conflict with any standard I'm
familiar with, but since \0 is already reserved as an octal
lead-in, having an "x" as the first "octal" digit shouldn't
cause any syntactic failure or semantic confusion.

Linda