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https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Technical_Notes/deployment.html

According to this, /etc/inittab has been deprecated. As suggested from this I created a /etc/init/serial-ttyS2.conf. After that I has to make the service start with the following command:

[root@sbc-l1c-pcc-00 ~]# initctl start serial-ttyS2

[root@sbc-l1c-pcc-00 ~]# ps aux | grep tty

root 7779 0.0 0.0 2016 536 ttyS2 Ss+ 13:38 0:00 /sbin/agetty/dev/ttyS2 9600 vt100

However when I try to connect no login prompt pop out, just a blank screen. I tried to restarted the serial-ttyS2 while the screen was still open and the login screen came out. And I have to do it every time I need to to connect. Does somebody have a clue why?

1 Answer 1

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Assuming that the missing space /sbin/agetty/dev/ttyS2 is not real, otherwise you have serious issues.

It's likely that you haven't asked agetty to monitor Data Carrier Detect. When asserted DCD means that there is a session in progress. DCD in turn requires DTR to be present, as Data Terminal Ready when asserted means that the other RS-232 lines from the terminal are not invalid.

Because of the lack of knowledge of the DCD (ie: user at terminal) status agetty doesn't know when a user connects, and thus can't present a prompt. Instead it waits for the user to press Return -- see the description of the -L option in man agetty for more information on this point.

Assuming you've got a correctly-cabled null-modem cable:

/sbin/agetty --8bits --flow-control -L=never ttyS0 9600

Otherwise you'll just have to live with people pressing Return.

You might find some hints in this blog post about serial terminals and Fedora 20.

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  • Hello, Thank for the answer and before investigating more I would like to understand what you mean with the first sentence "Assuming that the missing space /sbin/agetty/dev/ttyS2 is not real, otherwise you have serious issues".
    – dandan
    Jan 28, 2015 at 9:47
  • It should be /sbin/agetty /dev/ttyS2
    – vk5tu
    Feb 9, 2015 at 4:57
  • I see your point, sorry the output got all stuck together. Anyway it works, Simply I don't know why the first few times it wasn't answering to any keyboard input, until it did and instead of reloading the service I just have to press any key. Thank anyway
    – dandan
    Feb 9, 2015 at 16:34

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