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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