I have installed ArchLinux ARM on Raspberry Pi (Model B Revision 2.0).
The solution I am working on requires a Python script to send data over tty serial port /dev/ttyAMA0. This script should run automatically upon start-up without user interruption. The plan is to configure the start-up so that a special non-privileged user is logged-in automatically, and then a user start-up script is automatically executed.
However, I have problems with accessing the tty port.
The ownership of /dev/ttyAMA0 port is root:tty.
The special non-privileged user is enlisted in the tty group.
The problem is that the /dev/ttyAMA0 permissions by default are rw--w---- (620)
Without the read access to the port, the Python script can not initialize the port and the script fails.
The problem is easily fixed by executing
$ sudo chmod g+r /dev/ttyAMA0
But, this required user to enter the password, so this is not a solution for user-interruption-free auto-executed start-up script.
Please suggest some way how to fix this situation.