You are right back references are not implemented.

Giulia

On Fri, 20 Nov 1998 jean-michel.carsuzaa@icdc.caissedesdepots.fr wrote:

> We are looking for doing some regular expression substitution with the
> replacerules,
> using the back references of the regex.
> We are working with FS indexing, and we have a path like : 1998_08_17
>    
>    replace "(.+)_(.+)_(.+)" "/cgi-bin/toto?year=$1&month=$2&day=$3"
>    $1, $2, and $3 are not substituted.
> 
> We use SunOs 2.5. 
> Is it a problem with solaris regex implementation (C library?), any
> patch known for it ?
> Htdig seems to use posix 2 Gnu regex implementation, why swish doesn't ?
>