You won't find that answer on the community forums for OctoPrint - its an OS specific instruction that is outside OctoPrint.
The guide for installing Ubuntu on a Raspberry Pi has instructions: How to install Ubuntu Server on your Raspberry Pi | Ubuntu
I assume you should be able to find wherever you got the Ubuntu image from will have instructions on how to use it. This guide only details how to install OctoPrint on to an already working Linux device.
Just a thankyou to you although the instructions on that site were wrong too it did prompt me to go to the orange pi site where I found the instructions to set the wifi for my pi in server mode and then set the octoprint to allow the dialup and bingo got octoprint online on my orange pi so again thankyou 
Ok. For me, it was in /home/pi/mjpg-streamer/mjpg-streamer-experimental/scripts/webcamDaemon. Not sure how that changed, I'm using Ubuntu LTS and someone said this would work, can't remember who.
That would only occur if you created the file in that location instead of where the guide said to:
If you decide to deviate from what's above, you'll have to keep track of your changes on your own...
It may be worth noting that raspy-config needs camera turned on to get web-stream.
M117 string lengths beyond 85 characters cause ender 3 printers to get confused and ask for reset. This may happen with other printers also.
My install attempt is pi 4 pinn booting nspawn64 using the buster64 side to install OctoPrint. Web interface is up and running but will not connect to printer, Need to set up serial logging and run again,
Reminded again that copy & paste of commands is a line by line operation done carefully in the system you intend to update even if the next line is just 'make'.
(Same person on a different account)
I tried running that, "scripts" isn't in pi, it's in mjpg-streamer/mjpg-streamer-experimental, not sure how that happened, but it could explain why the webcam doesn't run on startup.
There is a scripts folder in mjpg-streamer-experimental, but that is for scripts that come with the repository - you can see it here. The guide is not suggesting to use that one, but to make a new one in /home/pi/scripts.
Do I make a new folder called scripts, because scripts isn't in pi
Turns out "scripts" wasn't there because I am running Ubuntu, and this is for RPi, used a copy guide but made for ubuntu, they just had the code to make scripts. Got that, but now, I don't know why, but same problem, not running on startup.
i found this command to be really helpful for weeding out haporxy issues
sudo haproxy -c -f /etc/haproxy/haproxy.cfg
Hello everybody,
today I noticed that the RaspiCam stream did not load anymore. The mjpeg-streamer itseft could be started by the webcamDaemon script did not start the stream.
The reason was that in the conditional start at the end of the script the output of vcgencmd get_camera was different on my pi (pi4b 4GB bullseye 32bit): instead of supported=1 detected=1 it returned supported=1 detected=1, libcamera interfaces=0.
So I had to change the elif statement a bit in order for it to trigger.
Instead of:
elif [ "`vcgencmd get_camera`" = "supported=1 detected=1" ] && { [ "$camera" = "auto" ] || [ "$camera" = "raspi" ] ; }; then
it is now:
elif [[ "`vcgencmd get_camera`" == "supported=1 detected=1"* ]] && { [ "$camera" = "auto" ] || [ "$camera" = "raspi" ] ; }; then
Maybe this helps if someone else runs into that issue.
Best regards Jörg
@foosel I just wanted to say thank you very much for this how-to! I have been struggling with getting Octoprint on a Banana Pi M2 Zero for about a week or so. With your guide I was able to get it installed on a the last version of Armbian that released for the M2 Zero (2020). Your instructions worked like a charm! Thank you!
I am having an issue with the venv. When I try and still pip or Octoprint, It states that "...locations that require TLS/SSL, however ssl module in Python is not available."
When I am NOT in the venv, I do not have this issue. So how do I get past this so I can install OctoPrint.
This is on a Raspberry PI 3 Model B
What OS have you installed?
Raspbian release 8.0 (jessie)
This guide is written to be used with Raspberry Pi OS based on Debian Buster (10) or Debian Bullseye (11). Jessie is way too ancient to be trying to install today.
A quick note for the next time these instructions are triaged;
I just setup a new bullseye/RPi4 box and noticed that In the optional webcam section you can drop the requirement to install subversion for mjpeg_streamer, it does not appear to be needed anymore, at least for Bullseye. Everything compiled and ran without it.
Not that there's any reason it wouldn't, but this all works great on 64-bit Raspberry Pi OS! Thanks so much for your work!
Linux raspberrypi 5.15.32-v8+ #1538 SMP PREEMPT Thu Mar 31 19:40:39 BST 2022 aarch64 GNU/Linux
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 11 (bullseye)
Release: 11
Codename: bullseye
instructions worked with a few minor tweaks to get octoprint along with a USB webcam up and running on an Orange Pi 3 LTS using the debian bullseye image from Orange Pi. I also just finished turning an old intel atom laptop that originally had windows 7 starter installed on it into an octoprint server using these instructions along with the raspberry pi desktop iso for PC.
very nicely put together instructions.