Questions about realport driver on Linux

Realport
1

My questions are as follows;

The realport driver for Linux states that a printer should be set up as
DG01:2345:once:cat < /dev/ttyaa11 > /dev/null &
dg01:2345:once:ditty-rp 38400 ctspace altpin -ixon -ixoff

Im not sure what the first part cat < /dev/tty…
is doing. My guess is that it clears the port am I right ? If I issue this on the command line it just sits there forever. The command ends with ‘&’ which says do this in the background. Ive tried this as well and the command just hangs. Ive also tried the ditty-rp to see if it affects the other command, but it doesnt seem to. The other command just hangs there. During the init, it seems to go away, because I dont see anything left over in a ps -ef output. Can anyone elaborate on what is really going on here ?

2

The cat command essentially “holds” the port open. This allows the following ditty-rp settings to “stick” on the port to keep the settings after a system reboot. It does run in the background and does not affect the functionality of the port (i.e. it does not block the port).