Behavior change in ${...//...}

Behavior change in ${...//...}

[Danek Duvall]

Between 4.0.x and 4.1.1, the requirements to quote a "/" in the
replacement part of a ${name//pattern/repl} expression changed from two
backslashes to one.  The new syntax doesn't work in the old versions and
vice versa.

When did this change, and why?  Is the best way to work around this to
put the replacement string in a variable?

Thanks,
Danek

Re: Behavior change in ${...//...}

[Peter Stephenson]

Danek Duvall wrote:
> Between 4.0.x and 4.1.1, the requirements to quote a "/" in the
> replacement part of a ${name//pattern/repl} expression changed from two
> backslashes to one.  The new syntax doesn't work in the old versions and
> vice versa.

See the README file for 4.0.7.


A change between 4.0.6 and 4.0.7 affects substitutions of the form
${foo/src/rep} and ${foo//src/rep}.  In 4.0.6, a literal `/' was quoted in
the `src' text with two backslashes.  This was documented, but inconsistent
with normal quoting conventions and poorly implemented.  The `/' now
requires only one backslash to quote it whether or not the expresion occurs
in double quotes.  For example:
  % foo=word/bird
  % print ${foo/\//-} "${foo/\//+}"
  word-bird word+bird
Note also the following workaround which is valid in all versions of the
shell that support this syntax:
  % slash=/
  % foo=word/bird
  % print ${foo/$slash/-} "${foo/$slash/+}"

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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Re: Behavior change in ${...//...}

[Danek Duvall]

On Thu, Sep 04, 2003 at 10:28:12AM +0100, Peter Stephenson wrote:

> See the README file for 4.0.7.

Ah, thanks.  I saw the change in the man page, but was only looking at
the 4.1.1 sources, and didn't see any reference to the change.

> Note also the following workaround which is valid in all versions of the
> shell that support this syntax:
>   % slash=/
>   % foo=word/bird
>   % print ${foo/$slash/-} "${foo/$slash/+}"

As it turned out (not too long after I sent my query), this was easier
for me to do than I had expected, and so I no longer needed some test
for which behavior to use.

Thanks,
Danek