Objective:
On a headless Raspberry Pi 3B+, resolve what the current installed OS version is, including checking if it’s in line with currently available version. This post is less about how to upgrade OS and more for basic version checks.
Procedure:
SSH into RP3B+ from RP5
-OK. Still need to resolve how to both shorten the password, as it’s just me internally doing this, and also how to automate the password from the RP5.
cat /etc/os-release
-Took me a while to figure out a couple things about this command. cat means to concatenate, which means to read an existing file and display on screen. This presupposes that after you do an install/upgrade, a file is written to /etc directory. This also means it’s not returning information from a live running process.
-It’s coming back saying that I have versio 13 Trixie. I’m less enamored about OS names, after dealing the MacOS several years back. IMHO, because of over identification, people liked to use the OS name more than the version number. I could not care less what the name is, as I have to resolve the version number in order to make sense of anything.
-The Debian version fill is 13.6. That’s interesting — does that mean it’s being more specific?
-I definitely have Raspbian GNU/Linux. OK.
lsb_release -a
-Focus here on output of Distributor: Raspbian; Description: Raspbian GNU/Linux 13 (trixie); Release: 13; Codename trixie
-Basically, the same information with specific variable names
uname -a
-Now we’re getting closer with more detail, as this should return Linux Kernel version. Remember that I installed the 32-bit headless version. Comes back with the name of the server (hostname).
-SMP Raspbian 1:6.18.50-1+rpt1 (2026-09-11) armv71 GNU/Linux
-I’m thinking the codebase that’s installed is a version from 9/11/26
-NOTE: I just learned that arm71 means 32-bit. If it returned aarch64, that would be 64-bit
-Not sure what the reference to: 6.18.50 is, as I thought it was version 13.6
NOTE: On my RP5, which is 64-bit 16GB I ran uname-a
-Version 16.8, and yes – aarch64. Debian version is 13.7, which makes sense as I’ve been doing auto-updates on the RP5 lately.
hostnamectl
-Reminds me that the archicture is “arm” – arm71 in my case
https://www.raspberrypi.com/software/operating-systems/
-When I go this site, I can see, based on a different flavors (32-bit, 64-bit), different specifics and downloads. This is coming from home-based of Raspberry Pi as well, so I’m trusting it
-Here’s the info for 32-bit headless, without desktop
Raspberry Pi OS Lite
A port of Debian Trixie with no desktop environment
| Release date | 6 Oct 2026 |
|---|---|
| System | 32-bit |
| Kernel version | 6.18 |
| Debian version | 13 (trixie) |
| Download size | 543 MB |
| Storage required | 2,656 MB |
Based on the date being 6 October, looks like my version and it’s 32-bit
That explains the 6.18. The Kernel version is 6.18
The Debian version is 13
I’m still learning the distinction between Debian and Kernel. Wild to think the whole OK is 543MB in size.
Summary:
-For now, I’ve achieved what I was after. I now understand the name of the OS (trixie); the Debian version; the Kernel version; confirmed bit level; resolved that what I have is still current as of 10/7/26.
-Now I just work on things like patches and updates
-I just noticed something. It said release date 6 October, which was yesterday. I installed over a week ago. That means that what is on the server is a newer version. Probably a sub update, as still version 16.8. So far so good.