sed -n '/<tileset\s\+firstgid="1"/ {
s/\(<tileset\s\+firstgid="1"\).*/\1/p
r /Resources/maps_sideScrolling/tileProperties.tmx
:loop
n
s/.*<layer name="background".*/&/p
t
b loop }' ~/Resources/maps_sideScrolling/*.tmx;