Episode: 2496
Title: HPR2496: Making a Raspberry Pi inventory
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2496/hpr2496.mp3
Transcribed: 2025-10-19 04:07:55

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This is HPR Episode 2496 entitled Making a Raspberry Pi Inventory and in part of the series
Bash-Cripting.
It is hosted by Dave Morris and in about 11 minutes long and carrying an Ecclicit flag.
The summary is how to collect identifying information about API devices.
This episode of HPR is brought to you by archive.org.
Find universal access to all knowledge by heading over to archive.org forward slash donate.
Hello everybody, this is Dave Morris for Hacker Public Radio.
So today I'm talking about Raspberry Pi's but really it's a talk about Bash in the context
of Raspberry Pi's so I've labelled it as part of the Bash series.
So the title is Making a Raspberry Pi Inventory.
Inventory.
Never know how to say that.
I've got quite a lot of Raspberry Pi's, maybe too many, there's one or two that are
not even in use.
But the ones I have are sometimes lose track of which is which and so I need to recall
that Raspberry Pi 5 is such and such a model, such and such a memory, etc etc.
So I want to be able to easily get hold of that information and make an inventory of them
all.
And so I wrote a little script which you can run on any Pi which will report what I considered
to be useful information about it.
I don't know if you know this, if you're into Raspberry Pi's but each one has a unique
serial number.
When you look it up it says the Raspberry Pi site says it's randomly generated so there
may be a few collisions but it's as close to unique as you can get without being actually.
There's also a revision number stored in the firmware which encodes various bits of information
about its release date model, PCB revision and memory size.
And my script codes this and produces something readable.
So I run a Wikimedia instance on a Pi I have done for years and years and I use this script
to record details of my Pi's and store it there and I have a page per Pi and go on about
what I've done with the Pi and what projects I'm planning for it and so forth.
So it's useful because my memory is awful so I need to write everything down.
So this episode is really talking about the script.
I'm not going to go into tons of detail about it, I'm not going to do a lambda line breakdown
of it but I will talk in general about it.
I've called it what Pi, what underscore Pi, it's a bad script as I've said.
There's a copy that you can download in conjunction with this show but that's going to be a static
copy and it's a bit of a work in progress so I may well be fiddling about with it.
Though it hasn't had any work done to it since April and 2017 but there's also a GitLab
repository which I've pointed to.
So if you want to grab a version you might be wisest to get that one, maybe grab the repository
and keep pulling from it perhaps.
It depends on you, I think it's worth having that's wasn't it?
But you might want to mess around with it, you might want to hack on it as well.
So I'm going to talk about the script.
So what I've done is I have included a listing of the script in the notes using the capability
I have within the PANDOX system I used to generate notes of producing a numbered listing
and I'm going to just refer to a few bits.
It's a moderately long script, it's 197 lines long but it's a fair bit of comments
in there and stuff.
So how do you convert the revision info that you get from the pie itself into more useful
information?
Well it's done by searching a table of data.
The table comes from a website which is, and I want to have a good reading out URL's,
but it's in the script, it's in the notes, but basically the last bit is RPI underscore
hardware history and it's from elinux.org.
And somebody there is maintaining this and it contains information about all pies up
to date.
So all I've done, now I could have got clever about this and scraped the site with the fancy
script, but I haven't done it that way, I have done it by simply cutting and pasting
the table.
There's a nice HTML table in there, cut and pasted it, copied and pasted it into this script.
This means that if new pies are released, the table in your script will be out of date.
So it would be necessary to repaste into the table.
Made the note here that if you do that, then you need to make sure that the tab characters
which are part of the stuff you get back from doing a copy and paste, because you just
get the data out of the HTML table if you do that.
It contains tabs as a field delimiter, so I have made sure that they are in the script
because they are using as a field delimiter by the script.
The searching of the table and the display of results, actually done by using AUK, and
it the script writes the program into a temporary file that the script has created and then executes
that program against the table, which has also been stored in a temporary file, different
temporary file.
You'll see that on lines 163-181, that's the code that's doing all of that.
The information that's used to do this is extracted from the pie from a virtual place called
slash PROC, slash CPU info.
You see that lines 156-1557.
So I've sort of started in the middle here, but the script starts off by checking objects
declared a bunch of functions.
Then it starts off by checking to see that the device it's being run on is a pie, because
you couldn't run this on your desktop or whatever, but it, in fact, I have done that, and
anyone, why is it not working?
Oh, I'm not on a pie at the moment.
You've got one terminal SSH to a pie, another one not, then it's easy to make that mistake.
But it tries to determine whether it really is Raspberry Pi, and it will exit with a report
if it's not.
But this code's only been tested against the the kid that I have, which is not very varied
just a laptop and a desktop at the moment.
So it might not work for you, so if it fails, let me know.
The script is worth mentioning that lines 107-109 consist of a bit of code that creates
temporary files.
It uses the command MK-Temp to create a file, and it then uses a thing I haven't talked
about in any of my episodes about Bash.
It uses a thing called Trap, and Trap is a mechanism which allows you to perform a task
when certain events happen, and the events that this is being set to trigger on is stuff
like the script being killed or exiting.
And what it does is it deletes these files, so there's no garbage left around.
They're in the slash temp, but I like to just clean them up because it's good practice
to do so.
It calls a function in the script called CleanupTemp with the names of the two temporary files.
I will be talking more about Trap.
I've got it planned for one of my later Bash scripting episodes, but I haven't got the
details sorted out yet, so it's a way off yet.
So it's not a huge lot to say about the script otherwise, and I could go into massive detail
about it, but I said I didn't want to do that.
I'm sure you don't want to hear it.
There are two other functions called network info and settings info, which pull various
other bits of information out of the pie, so it reports stuff about the network.
It may not be as general as it could be, so again this has just been tested what I have.
You may have more esoteric setup, so it might not work entirely for you, and if that's
the case, then it would be interesting to know about it so I could improve it.
Indeed, if you have suggestions about improvements, then please let me know, and you can do that
by submitting a pull request to the GitLab repository.
The settings info was a suggestion, I think, from Ken Fallon, and it does stuff about the
video settings on the machine, which is not a thing I'm particularly bothered about personally,
but I did it because Ken suggested it, and it seemed to be something others might want
to know about.
What does it look like?
What does the output look like?
Well, there is an example running against one of my pies, which I call pie 2, RPI 2.
And you can see that it's in the show notes.
You can see that it reports the various bits of information that it's pulled from the table,
so you can tell that this is revision 10, I assume that's a 10.
With the release date of the third quarter of 2014, it's a Model B plus, and it's 512
megabytes of memory.
It has a serial number.
I've blanked it out because I don't know how sensible it is to put your serial numbers
out on the web, so I thought, I better not.
There are various configuration details reported, including the CPU temp at the moment.
The device is sitting on a shelf just above my head, so I'm just now with another device
on top of it, so it might be getting hotter than it should.
I don't know if 39 degrees C is exceptionally hot.
Don't think it has a heat sink on it, so maybe that would be a smart move.
And then the network information, the host name is RPI 2, it's got an IP address, it's
got a MAC address, so I changed the MAC address as well.
But you can download that if you want to.
I'm not really sure what you want to, but if you want to check out the script on the
PI of your own, you'll get a report similar to that.
Hopefully, if not, let me know.
That's really all I have to say.
I hope you find it useful.
It's a simple thing.
You can just cut and paste the report, stick it somewhere or other, where you want to
keep the information about your PI.
And if you can think of enhancements or improvements or bug reports or whatever, then let me
know.
That's it.
Okay.
Bye.
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