This script is no longer maintained! If it still works for you then great, but I won't be making any further changes to it. It was last edited in 2013, and many parts of the Raspberry Pi ecosystem have changed since then.
Simple script to easily enable & disable the Raspberry Pi's serial console. Disabling the serial console is required if you want to use the Raspberry Pi's serial port (UART) to talk to other devices e.g. microcontrollers (see http://elinux.org/RPi_Serial_Connection for more information).
Note that this script is now partially redundant, as the latest versions of raspi-config feature something quite similar already built in.
To install rpi-serial-console, simply run:
sudo wget https://raw.githubusercontent.com/lurch/rpi-serial-console/master/rpi-serial-console -O /usr/bin/rpi-serial-console && sudo chmod +x /usr/bin/rpi-serial-console
To display whether the serial console is currently enabled or not, simply run:
rpi-serial-console status
To enable the serial console, simply run:
sudo rpi-serial-console enable
To disable the serial console, simply run:
sudo rpi-serial-console disable
What could be easier than that?! ;-) After enabling or disabling the serial console you'll need to reboot Linux for it to take effect.
Behind the scenes it automatically edits
both /boot/cmdline.txt and /etc/inittab, adding or removing the
ttyAMA0 options as necessary. The very first time you run
rpi-serial-console it automatically creates backup copies of these
files with a .bak extension.
If rpi-serial-console detects that the serial console is enabled in
/boot/cmdline.txt but disabled in /etc/inittab (or vice-versa) then
it'll tell you and refuse to do anything. After manually correcting the
problem, then rpi-serial-console should run fine again.
This script has only been tested on Raspbian, so please file an issue if it doesn't work on your distro of choice.
When enabling the serial console, rpi-serial-console will set it by default to a baud rate of 115200. But if for some reason you want to change the baud rate the serial console uses, you can supply this as a second argument. For example to set the serial console to a baudrate of 57600, you'd use:
sudo rpi-serial-console enable 57600
and then reboot. If the serial console is already enabled, and you want to change the baud rate, then simply use rpi-serial-console to disable it, enable it at the new baud rate, and then reboot.