reldir

open source bios with linux platform, very good and can be reused.

#!/bin/sh

PREF="."
for x in 0 1 2 3 4 5 6 7 ; do
    test -f $PREF/config/configure.in && break
    PREF="../$PREF"
done
ROOT=$( echo $(pwd) | sed "s,\(//*[^/][^/]*\)\{$x\}/*\$,," )
RELNAME=$( echo $(pwd) | sed "s,^$ROOT/*,,g" )
echo $RELNAME