Just a sanity sanity check, lp the attached file to one of your HP printers.
Just
lp -dHPprinter
no duplex command which is embedded.
Remove the .txt extension so the filename is duplex.prn
Just a sanity sanity check, lp the attached file to one of your HP printers.
Just
lp -dHPprinter
no duplex command which is embedded.
Remove the .txt extension so the filename is duplex.prn