how to duplicate /dev/ttyUSB0 stream?

Question

Is there a way to duplicate a serial device /dev/ttyUSB0 on Linux (Ubuntu 14.04) ?

I made a program which read the data from the RS232 port and I would like to execute two instances of my program with different options in parallel. However, I cannot open the /dev/ttyUSB0 twice from my program (writen in C).

Ideally, I would like the ttyUSB0 driver to create two identical devices. (/dev/ttyUSB0 and /dev/ttyUSB1). The driver would make sure that ttyUSB1 is an exact copy of ttyUSB0.

Is there a way to perform this from the command line (bash) or should I make my own special serial port driver ?

chepner chepner · Accepted Answer · 2016-07-13T20:59:09

You can use tee to output anything written to /dev/ttyUSB0 to two named pipes.

mkfifo copy1 copy2
tee copy1 copy2 < /dev/ttyUSB0 > /dev/null &
program1 < copy1
program2 < copy2

(Strictly speaking, you only need one named pipe; the other program could read from an anonymous pipe connected directly to tee. This symmetrical treatment is a little cleaner, though.)

how to duplicate /dev/ttyUSB0 stream?

1 Answers