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Is there a way you can query the model and revision of a Pi from a script without accessing files that are generated at install time for the OS? I have a project where a web page needs to display the model and revision of the Pi it is installed on, and I'm currently getting the info by looking at the revision number in /proc/cpuinfo. However, that file is populated when the OS is installed. The goal is to be able to have a single image that can be installed on either the Pi 2 or 3 and the page should be able to identify the model regardless of which Pi the image is installed onto.

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Files inside /proc are not "installed".

/proc is a virtual filesystem. No files inside /proc exist on the SD Card.
They are created by Linux on every reboot and only exist inside RAM. Try the following command to get a model name, for example:

 cat /proc/device-tree/model

Linux itself will create, delete and modify files inside /proc to represent internals (id + memory addresses of processes, CPU cores, USB devices etc. etc.)

The files inside /proc will always be different even if all your Pis run the same image.

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  • Huh... that's interesting. I've tried the same image on two different Pi's though and both said Pi 3 when one of them was a Pi 2, and I was grabbing from /proc/cpuinfo. I assumed since the image was made when that file already existed, then installing the image on another Pi would result in the same info in that file. – Darin Beaudreau Jan 16 '19 at 17:46
  • @DarinBeaudreau Later model Pi2 use the same SOC as Pi3 – Milliways Jan 16 '19 at 21:07
  • Right, but the revision number is different for every model. That's what I was looking at. The problem was that I forgot to delete the page that was generated with the info already on it before creating the image. I just needed to delete it so it would re-create the file with the correct info on the page. – Darin Beaudreau Jan 16 '19 at 21:44
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To elaborate the answer from @flakeshake: files under /proc/ and /sys/ are called pseudo files. They are the interface from the kernel to the user space. The kernel shows its settings with them. So if looking at /proc/cpuinfo you get the info from the kernel it just see at the time you ask for it, e.g. with cat /proc/cpuinfo.

You can also modify the kernel settings by writing to pseudo files. For example look at network settings with ls -l /proc/sys/net/ipv4. Nearly all pseudo files there are writable so you can fine tune your network but you can also make it complete unusable ...

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  • @DarinBeaudreau You can respect it by upvote ... – Ingo Jan 16 '19 at 21:49
  • I did, but it's not visible because I only just joined this particular community. – Darin Beaudreau Jan 17 '19 at 20:04

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