Add an image as a background to a previously manipulated image with Imagemagick -

i'm writing script that:

• scales
• crops
• adds background image

to series of around 400 transparent pngs. i'd make run fast possible.

currently i've got 2 separate commands:

convert $input.png -scale $scale% -gravity center -crop 640x640+0+0 +repage $output.png composite -gravity center $output.png $background $output.png 

is there way reduce single command? i've been looking @ docs -composite can't see way add image background after doing other manipulation.

any ideas? thanks

why don't use && between 2 commands? second command executed when furst exits without error... should work...