In my Office, I use a relatively small computer devices. I setup those boxes as router, located in network panel room together with switch and cable closet. There’s no monitor or keyboard there. So when there’s any error, I need an quick solutions to see what happened while boot.
I tried this with Ubuntu 10.04. This tutorial is not compatible with Ubuntu below 10.04.
First we set the getty, so we can log-in through serial console.
$ sudo vi /etc/init/ttyS0.conf
# ttyS0 - getty
#
# This service maintains a getty on ttyS0 from the point the system is
# started until it is shut down again.
start on stopped rc RUNLEVEL=[2345]
stop on runlevel [!2345]
respawn
exec /sbin/getty -L 38400 ttyS0 vt102
Then we setup the grub loader so it can show on serial ports too. Just adjust your grub configuration with this configuration.
$sudo vi /etc/default/grub
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
GRUB_DEFAULT=0
GRUB_TIMEOUT=1
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,38400n8"
# Uncomment to disable graphical terminal (grub-pc only)
GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --speed=38400 --unit=0 --word=8 --parity=no --stop=1"
# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true
After editing grub configuration, we update our grub with this command:
$sudo update-grub
Before we test the grub loader with serial, we should test the getty program. Now, on client computer, we install minicom program. I’m using USB2Serial that detected on port /dev/ttyUSB0. I use 38400 baud speed. Just adjust the 38400 with other speed if you like.
Let’s install the minicom program with this command:
$sudo apt-get install minicom
After that, launch the minicom program. Set the configuration like this. Press ^ao on the minicom screen.
+-----[configuration]------+
| Filenames and paths |
| File transfer protocols |
| Serial port setup |
| Modem and dialing |
| Screen and keyboard |
| Save setup as dfl |
| Save setup as.. |
| Exit |
+--------------------------+
Choose “Serial port setup”
+-----------------------------------------------------------------------+
| A - Serial Device : /dev/ttyUSB0 |
| B - Lockfile Location : /var/lock |
| C - Callin Program : |
| D - Callout Program : |
| E - Bps/Par/Bits : 38400 8N1 |
| F - Hardware Flow Control : No |
| G - Software Flow Control : No |
| |
| Change which setting? |
+-----------------------------------------------------------------------+
After done configurating, Save it as default by choosing “Save setup as dfl”. Then Let’s try to initialized the serial by pressing ^am . If success then we have a login prompt.
Ubuntu 10.04 LTS ro-bb-fa-fb-fe ttyS0
ro-bb-fa-fb-fe login:
On the login screen we know that we use serial console by “ttyS0” It’s mean we use serial 0.
Reference:
[1]https://help.ubuntu.com/community/SerialConsoleHowto
[2]http://www.vanemery.com/Linux/Serial/serial-console.html
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