For testing purposes I want to use socat to create virtual serial ports to use in my Python program.
I have limited success, but struggle again and again with the many options in socat. I use this command in Ubuntu Linux:
sudo socat -d -d pty,b9600,raw,echo=0,link=/dev/ttyS90 pty,b9600,raw,echo=0,link=/dev/ttyS91
As it should, it creates the virtual ports like /dev/pts/2 and 4, and links them to /dev/ttyS90 and *91. It does not work without sudo (it fails with unable to unlink for the *90, *91 ports, although the regular user is in the dialout group).
But as you see the permissions 'lrwxrwxrwx' look like reading/writing for everybody. However, this is NOT true: I CANNOT use these devices unless I am root. The file manager (=Nemo) gives this result:
The permissions are significantly different. Huh?
After issuing 'sudo chmod 777 /dev/ttyS90' (and same for *91) nothing changes in the terminal output, because it is already, but incorrectly, showing 777 permissions, but the Nemo output changes to
And now I can use the ports as regular user! How comes? Am I doing something wrong?
And one more socat problem: the above socat command gives an 8-bit, no-parity connection, but I really need a 7-bit, even-parity connection. My attempts to implement this by juggling some of the many options all failed. I am lost; any insight?
