Configuring a Surveillance Camera with Udev and Systemd
Say Cheese
© Photo by Shaurya Sagar on Unsplash
You can use systemd to make your computer react when you change a file or plug in a device. We'll show you how to leverage these powerful features to build a surveillance system.
In modern Linux systems, the Udev device manager listens for notice of new devices added to the system. If a device is detected, Udev can trigger an action. In most situations, Udev operates behind the scenes. You don't have to be an expert in Udev to boot your computer or plug in a device, but if you feel like experimenting, you can configure Udev directly to automate an action. There's a good chance you are already familiar with starting and stopping systemd services by hand or enabling them to start at boot, but you can also have them start when certain ad hoc conditions are met. You could, for example, have systemd trigger an event when you plug in new hardware or when things change in the filesystem. You do that by combining a Udev rule with a systemd service.
This article shows how to leverage the kernel's Udev device manager and systemd's Device and Path units to create a home surveillance system with Single Board Computer (SBC) and an off-the-shelf webcam. The idea is that, when the SBC detects the camera has been connected (or when it detects the camera on boot), it will trigger a surveillance service that will take a picture every few seconds. If the surveillance script detects movement, it will save the images to a predetermined folder. These images will be saved with a unique date-and-time-based name.
I have several SBCs lying around from bygone eras, some never used and still in their original boxes. I picked a PINE 64A [1] (Figure 1), but any device that can run Linux will do. In my case, I'll use a version of Arch Linux that works well with the PINE 64A's ARMv8 architecture [2].
[...]
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
AI Helped Develop a Linux Exploit
A use-after-free race exploit was discovered and exploited on CentOS Stream 9.
-
Yet Another Linux Kernel Vulnerability Discovered
Affecting millions of systems, a kernel flaw discovered by Qualys could allow users to gain root privileges.
-
Ubuntu 26.10 to Include Ubuntu Certified Hardware Check
If you've ever wondered if your laptop or PC is officially certified to run Ubuntu, that curiosity will soon be met.
-
Substantial Update to IPFire Now Available
The lastest version of IPFire features a fundamental change to how the system handles DNS.
-
Gnome Working on Test Center App to Make Testing Easier
It's now possible to test experimental features on the Gnome desktop without worrying that you'll break things.
-
New Vulnerability Discovered in Linux Kernel
Hiding out for nearly 15 years, the Ghostlock vulnerability allows a standard logged-in user to gain root privileges.
-
New Linux Flaw Lets Attackers Escape VMs
A 16-year-old vulnerability allows an attacker to escape a virtual machine, gain access to the host, and execute malicious code.
-
Hannah Montana Linux Is Back!
Developer Noah Cagle decided the world needed the once obscure but beloved Linux distribution and gave it a decidedly pink refresh.
-
System76 Refreshes the Lemur Laptop
If you're looking for a laptop with tons of power and battery, look no further than the latest iteration of the System76 Lemur Pro.
-
More than 43 Million Lines of Code in Linux Kernel 7.2
Using the cloc utility, Michael Larabel of Phoronix discovered that Linux kernel 7.2 has over 43 million lines of code.