I’m working on a some materials for a class wherein I’ll be teaching some young, wide-eyed Windows nerds about Linux and we’re including a section we’re calling “foot guns”. Basically it’s ways you might shoot yourself in the foot while meddling with your newfound Linux powers.
I’ve got the usual forgetting the . in lines like this:
$ rm -rf ./bin
As well as a bunch of other fun stories like that one time I mounted my Linux home folder into my Windows machine, forgot I did that, then deleted a parent folder.
You know, the war stories.
Tell me yours. I wanna share your mistakes so that they can learn from them.
Fun (?) side note: somehow, my entire ${HOME}/projects folder has been deleted like… just now, and I have no idea how it happened. I may have a terrible new story to add if I figure it out.
have an nvidia GPU
have Fedora
download RPM package of drivers for Red Hat (after all, Fedora and Red Hat are… compatible, right?)
Everything goes fine
Six months later, upgrade to a new version of Fedora
oops, kernel panic at boot after the upgrade, and no video to troubleshoot after UEFI boot
figure out how to boot into a recovery partition from UEFI
figure out how to enable a serial console over a USB device
figure out how to connect to the serial console from another computer using another USB device
figure out what the kernel panic is from (not the upgrade, but the driver which wasn’t upgraded)
figure out how to uninstall the incorrectly installed driver
figure out how to install the correct driver
That was a fun three week OS upgrade.
I have a super-n00b question, and I apologize in advance, but, uh…yeah, what is a serial console?
You attach a secondary computer via serial (COM port) with your primary computer and then you can open a console on that one. You can access the primary computer as if you would be sitting in front of it.
You probably have to explain what Serial actually is.
I mean serial is just a port that runs in serial. You send something and you receive something afterwards, after you’ve received you can send again…
Not all people know that, to be fair.
True. It’s not quite common nowadays unless you work in administration or are an enthusiast.
https://en.wikipedia.org/wiki/Serial_port
Because there’s going to be kids around here who have never seen this port (other than maybe on a Point Of Sale (POS) system?)
Lol, I appreciate it, but I’m actually old enough to remember those! I know what a serial port is; I just didn’t know what a serial console was or if it was related. Haha.
Tl;dr: Stick in a USB cable and the other side gets your console.
Adding to what DmMacniel said, it’s a hardware interface, often accessed via a USB port (which after all, is the universal serial bus).
Christ you guys are making me feel old. I remember back in the day when a serial connection was made through an actual serial port. I know I have some serial cards around here somewhere. I have also used the tar command on an actual tape… Here’s a fun fact, if your tape drive (big reel to reel looking thing, not a cassette or other kind of ‘tape’) has an issue with rewinding, do not use your finger to manually spin the reel. Use a pencil. I finished reeling my tape back up once and realized I now had a blister on the end of my finger.
My motherboard which is only a few years old (2ish?) has serial port pin outs.
https://en.wikipedia.org/wiki/Serial_console
tl;dr:
Serial ports are (for example) commonly RS-232, although other types of ports exist. Imagine it to be a very slow Ethernet device. Because it’s so slow (and the technology predates Ethernet and also has different requirements), it’s usually attached directly to a device instead of to a network. But you could connect a modem to it and it becomes connected to a network device.
It could also be connected to a system console device. These are commonly called terminals. Such devices are often monochrome (especially older ones) because a serial connection is often bandwidth limited (eg, measured in kilobits per second instead of megabits or gigabits). Since it’s so slow, it’s not practical for video, so it’s generally just text-only.
Note that your GPU might also output a system console but rendered on your display at very high resolution and with graphics-drawing capabilities. So a system console would be any console that connects to the system.
What is a console? Well, Wikipedia presents several valid articles and the common theme as far as computers go is that a “console” is typically something that a human and a computer use to interact with each other.
For serial consoles, you might find device files for them at
/dev/tty*. But for general serial devices, it could be any of several different types of device files.Wikipedia’s article on
/devdevices has a pretty decent listing of what kinds of devices you might find and several of them might be classified as a serial port. Any serial port might be connected to a serial console.So in my case, a serial console is:
That’s pretty much it in a nutshell. Then
grubconfiguration to enable a serial console on the attached USB-to-serial device file and saves changes, then unmounts failing system partitionscreen(oh wow those were some old days)To be fair, a lot of that complexity could have been done by either reinstalling, or removing the hard drive and attaching it to another computer. But doing it this way allowed me to poke around and try different ways of solving the issue, rebooting, etc. It was a learning experience worth exploring.
It was years ago though and I think there was some complication with trying to understand what device file (or device number or something) needed to be to work on the correct serial device (there are often multiple)
Wait, that’s a tl;dr to you? o_O
I felt the same way so I scrolled down hoping for a shorter answer, but found yours instead and it made me laugh my ass off because how you wrote it really hit me, are you me? xD so I just wanted to say thanks for making my day even better!
Haha I’m really glad I could make another person laugh today! xD
I’ll quote my current boss’s boss’s boss when he asked a question of me:
Why would you need a serial console? Live USB is a thing