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TiFFolk
Asked: 2009-10-30 10:16:16 +0800 CST

How to configure UNIX or Linux for administration via serial connection

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How can I configure my UNIX or/and Linux PC with COM port to support serial console connections? I would like to connect my notebook to that PC via a console cable and manage the PC with terminal emulation software like putty, as if I use keyboard directly.

console

4 Answers

  1. Best Answer

    I have this line in /etc/inittab on a server I run that has a serial console:

    T0:23:respawn:/sbin/getty -L ttyS0 57600 vt100

    ttyS0 is the serial port. That's all there is to it, at least here.

    Edit: You'll probably want something like this in your grub.conf:

    serial --unit=0 --speed=57600
terminal --timeout=10 serial console

    And then with each kernel:

    kernel /boot/vmlinuz ro root=/dev/md1 console=tty0 console=ttyS0,57600

    (The important part is the console= arguments)

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  2. In addition to the other answers, I'd suggest looking here:

    http://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/

    Specifically, the GRUB section so that you can get the boot menu too (not just the OS once it begins to load):

    http://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/configure-kernel-grub.html

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  3. See the other answers if your distro uses inittab. But Ubuntu uses /etc/event.d and most other distros are or will as they adopt the more modern init daemon Upstart. At least it will eventually get rid of those hideous System V "run levels".

    If you do have a /etc/event.d/, in there you should have tty1, tty2, .... You may need to copy one of the tty files to ttyS0. (Check /proc/devices to see what you have.)

    These files look something like:

    # tty1 - getty
#
# This service maintains a getty on tty1 from the point the system is
# started until it is shut down again.

start on stopped rc2
start on stopped rc3
start on stopped rc4
start on stopped rc5

stop on runlevel 0
stop on runlevel 1
stop on runlevel 6

respawn
exec /sbin/getty 38400 tty1

    Be sure the device name and the speed are what you want.

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  4. You just tell the machine you want to connect to with the serial console to listen on a serial port. Most Linux distributions come with examples in their /etc/inittab files that show how to do it (look for /dev/ttyS0).

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