Re: set -x output of test operator is irretating

[Bob Proulx]

Chet Ramey wrote:
> Toralf Förster wrote:
> >        I'm wondering why in the example (see below) the right side is 
> >        prefixed with a '\' wheras the left side is unchanged.
> >...
> >        tfoerste@n22 ~ $ echo "1 2 3 4" | while read a b c d; do [[ "$a" = 
> >        "$b" || "$a" = "$c" || "$a" = "$d" ]] && echo oops; done
> >        + read a b c d
> >        + echo '1 2 3 4'
> >        + [[ 1 = \2 ]]
> >        + [[ 1 = \3 ]]
> >        + [[ 1 = \4 ]]
> 
> Because the ==/!=/= operators are defined to match the rhs as a pattern
> unless it's quoted.  You quoted the original string, and the `set -x'
> output is supposed to be re-usable as input, so the trace output is
> quoted appropriately.

Of course that makes sense for the "==" and "!=" cases.  But is that
true even for the "=" case?  For the "=" case I thought it was
"STRING1 = STRING2" and not "STRING = PATTERN".

Could you clarify the rules and educate us?

Thanks
Bob