Print in silent mode on Mac

I need it to do a print in silent mode without opening the openprinterdialog On Mac. On Windows works well, but not on Mac.

you can print a file with a shell

shell.execute "lpr " + file.ShellPath

I tried this:

lpr -P Brother_QL_570 image.png

Exits in the print queue, but does not print.

image.png - this will not be the right path

drop the file image.png to a terminal window and you see the shellpath