Linux Command line Serial Communications

First, you must have permission to access the serial device. In some versions of Linux, you must add the user to the dialout group then restart the session. In others, serial devices may be a part of a different access group, e.g. uuid or serial. Try using stat /dev/ttyport with your devices port, and look for the "group" or "group ID" or "GID" to see what group you need to be in.

Once you know the serial device group, you need to add that group to your user. Again, this is different on different versions of linux, but look for commands like
usermod -a -G dialout $USER
adduser $USER dialout
in each case replacing "dialout" with the name of the serial access group. Note that these will always require sudo or root access to change user groups.

For interactive connections to a serial console:

# screen - screen manager with VT100/ANSI terminal emulation. e.g.
screen /dev/ttyUSB0 9600
# just specify the port and speed
#    /dev/ttyUSB0         Use /dev/ttyUSB0 as terminal
#    9600                 Open the serial port using 9600 baud

While in screen, use the following commands:

• Ctrl + A, \ - Exit screen and terminate all programs in this screen. It is helpful, for example, if you need to close a tty connection. (this is Ctrl + A, Ctrl + \ in some cases)
• Ctrl + D, D or Ctrl + A, Ctrl + D - "minimize" screen and screen -r to restore it.
• Ctrl + A, ? - Show help for all the possible commands. Note you must press space to leave the screen then press Ctrl + A and the command you wish. You can't execute the command from the help screen.

For more complex settings, use stty:

//from the command line, set a USB serial adapter, then interact, ctrl-c to exit
stty -F /dev/ttyUSB0 ospeed 57600 ispeed 57600 raw
cat /dev/ttyUSB0 & cat > /dev/ttyUSB0

//from the command line, set a USB serial adapter and send and receive data
stty -F /dev/ttyUSB0 ospeed 57600 ispeed 57600 raw
echo -ne '?' > /dev/ttyUSB0
cat -v < /dev/ttyUSB0

  .