[SOLVED] Is there a way to do multiple shell variable expansions/parameter substitutions?

Issue

I have a line in a script that works in zsh but does not work in bash:

SHORTDIR=${${${PWD##*/}//./_dot_}//:/_colon_}

This is basically a short/efficient version of basename $PWD | sed -e 's/\./0/g' -e 's/:/1/g'.

What's the syntax for stringing together variable expansions?

Solution

Sadly, the first part of the substitution has to be a parameter name. An alternative sed version would be:

echo $PWD | sed -e 's!.*/!!' -e 'y/.:/01/'

Answered By - perreal