Regexp replace

I just stumpled again over the fact that it is not possible in Igor to replace a regular expression sub pattern by a string.

On the command line this would be something like

echo "abcd 1" | sed 's/\([a-z]*\)\s*\([[:digit:]]\)/\2_\1/' 1_abcd

I've seen that Igor uses PCRE, the new PCRE version 2 supports that using