There are a few cases in the life of a RaspberryPi owner when it can be useful to view the RaspberryPi's last bootlog. The bootlog is basically the – much more detailed – diary of your RaspberryPI.
All system-relevant events are entered in the bootlog.
This is particularly useful if you are looking for the cause of a specific problem. Because you can then check in the bootlog whether anything system-relevant happened last (i.e. before the crash/error).
How you can display the bootlog is described in the following article.
Safety instructions
I know the following notes are always kind of annoying and seem unnecessary. Unfortunately, many people who knew "better" have lost eyes, fingers or other things due to carelessness or injured themselves. Data loss is almost negligible in comparison, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Because even the coolest project is not worth injury or other trouble.
https://www.nerdiy.de/sicherheitshinweise/
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Requirements
Helpful articles:
So that you can view the bootlog of your Raspberry Pi, it should of course be prepared so that you can access it via SSH.
The following three articles describe what needs to be done to prepare the RaspberryPi:
RaspberryPi – setup for nerdiys!
RaspberryPi – The first configuration!
RaspberryPi – Control the RaspberryPi via SSH
Required tool:
-no-
Required material:
In the following list you will find all the parts you need to implement this article.
Log in to the RaspberryPi via SSH
To start, you must first log in to the Rasp Pi with Putty via SSH. How to do this is in the article RaspberryPi - Control the RaspberryPi via SSH described.
View complete bootlog
Viewing the complete bootlog is possible without much magic with the following command:
dmesg
Nerdiwssen:
„dmesg“ ist die Abkürzung/Befehl für i.edisplay messatge. This program prints the kernel messages on the screen.
Filter bootlog for specific words
Da der Befehl „dmesg“ ohne weitere Parameter den kompletten Bootlog ausgibt kann es manchmal etwas mühselig werden, darin nach einem bestimmten Schlüsselwort zu suchen.
Seid Ihr zum Beispiel auf Spurensuche nach einem Fehler mit einem USB. Gerät so könnt Ihr die Ausgabe mit folgendem Befehl nach Zeilen filtern in denen das Wort „USB“ vorkommt.
dmesg | grep -i usb
Dabei gibt das „-i“ an, dass beim Suchwort „usb“ die Groß- und Kleinschreibung ignoriert wird. Es werden also sowohl Zeilen in denen „usb“, „USB“ oder andere Kombinationen aus Groß- und Kleinschreibung vorkommen, ausgegeben.
Have fun with the project
I hope everything worked as described for you. If not or you have questions or suggestions please let me know in the comments. I will then add this to the article if necessary.
Ideas for new projects are always welcome. 🙂
PS Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you think it's cool that I share the information with you, I would be happy about a small donation to the coffee fund. 🙂
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