3d ago

Every time

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reset is your friend. Less so these days with GUIs where it's often quicker to close the window and open a new terminal emulator, but still good to know about in a pinch. That rare occasion where you're actually on a console and Ctrl-Alt-F# isn't available, or attached to a remote session where disconnection might mean you can't get back on, etc.
The man page suggests Control-JresetControl-J as the correct sequence to run it, because the Enter key might have had its behaviour altered. And if things are still slightly weird after the reset, run its parent tset.
- https://stackoverflow.com/questions/47503734/what-does-printf-033c-mean
  This has helped me when reset failed.
- That rare occasion where you’re actually on a console
  Actually having login console on a serial port can be pretty useful if you screw up something with network on a headless PC. I wish modern computers still had that as it also works better than USB adapters.
  
  The motherboard I am using for my homeserver does have a com port, but I have yet to do anything with it (also I don't know how I would connect to it)
  
  I connect to mine with a USB serial adapter, since my laptop doesn't have one built-in, which I wish it did. Software-wise, I just use screen because I am lazy to use something like Minicom.
  Just don't set any low baud rate for Linux. It will wait for logs to be printed out while booting. Though perhaps you can reduce the loglevel, I haven't tried that. I've tried 300 baud for fun, and that wasn't fun. I think it was over half an hour to boot up just waiting for logs to print.
  I honestly don't remember what I did, but this lies in my /etc/default/grub and looks relevant:
  <>
  
  GRUB_CMDLINE_LINUX="console=ttyS1,115200" GRUB_TERMINAL_INPUT="console serial" GRUB_TERMINAL_OUTPUT="gfxterm serial" GRUB_SERIAL_COMMAND="serial --unit=1 --speed=115200"
  Also it's useful to then set width, height and terminal type. I think terminal type is in $TERM , and size is set with stty, but I am not sure. It's been a while.
  You may also need a "null modem adapter" to reverse RX and TX, but oddly enough, that actually makes it not work with my adapter, despite it also working when directly connected to a switch. Maybe it can figure out which end it's supposed to be? Dunno.
  
  Alternatively you can also start a serial tty as a systemd service if you're looking to troubleshoot after boot primarily. I do this on my server for VM networking misadventures.

39 comments