Re: set -x output of test operator is irretating

[Jan Schampera <jan.schampera@xxxxxx>]

Bob Proulx wrote:
> 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".

"When the == and != operators are used, the string to the right of the 
operator is considered a pattern [...]"

From the description for [[ ]].

= and == should make have difference in behaviour.

J.