for file in ./*.gv;
do
filestem=${file%.gv};
sed 's/\(CHUNK[0-9]*\)-\(0 \)/\1_\2/g' $file > ${filestem}i.gv;
done

for file in ./*i.gv; 
do 
filestem=${file%i.gv}; 
dot -Tpng $file > $filestem.png;
done

rm *i.gv
