bug-bash
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: set -x output of test operator is irretating


From: Jan Schampera
Subject: Re: set -x output of test operator is irretating
Date: Thu, 31 Jul 2008 18:00:22 +0200
User-agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509)

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.
...
address@hidden ~ $ 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.




reply via email to

[Prev in Thread] Current Thread [Next in Thread]