Socat – Unbuffered Socat Command to Connect Serial Ports in Remote Machines and Log Data

bufferpipesocatssh

I'm currently using the following command. It reads from serial ttyUSB0 in local machine, and bidirectionally connects to ssh, through two tee commands for logging. On the remote end, socat connects stdio to the remote ttyUSB0:

stty -F /dev/ttyUSB0 raw 3000000

ssh  admin@remote.local stty -F /dev/ttyUSB0 raw 3000000

socat /dev/ttyUSB0,raw,echo=0 SYSTEM:'"tee -a log_l2r | ssh  admin@remote.local socat - /dev/ttyUSB0,raw,echo=0  | tee -a log_r2l"',pty,echo=0

  1. I want to make sure buffering does not spoil the realtime communication between two robot controllers. Line buffering is ok, but nothing more.
    There is many connections in the above command and I'm unsure about potential buffered pipes/sockets. Could you help me spot them?

  2. Also I need to remove any translation or echo (I believe stty ... raw ... already does this).

  3. Is there some other preferred approach to solving this communication problem? i.e. other command?

Running Debian GNU/Linux – Ubuntu

Best Answer

If you get stdio buffering apply the stdbuf command as a prefix to the actual command.

stty probably needs an explicit -echo.

For an alternative, if you don't need ssh encryption, look at the usbip module for making a usb device on one machine visible on another.

To avoid the tee logging, just use socat -v to get a copy of both data streams on stderr.

Related Question