#!/bin/bash
shopt -s extglob
var=123abcd45ef
echo ${var/+([[:lower:]])/} #1ière occ. de munisc.

var1=123a45bcdef
echo ${var1/+([[:lower:]])/}
var2=ab123cdefgh45ij
echo ${var2//+([[:lower:]])/} #toutes occ. de minusc.