Clipboard History for Linux

This project is a lightweight clipboard listener daemon for Linux. I started the project because I was missing the Win+V shortcut when I switched to my Ubuntu and I was very used to using the feature. It is just more fun to make one of your own instead of downloading third-party clipboard manager.

The journey turned out to be quite interesting.

My first goal was to first understand how the clipboard works in Linux. I came across by-far the most interesting thing and that is the middle mouse button paste. I was shocked by the existence of this feature. If you still didn’t get it, you can select a piece of text and press the middle mouse button in any other text box, and BOOOM!!!

My first thought was to store the clipboard data in a DB. But then I thought about what a clipboard actually contains. Passwords. API keys. SSH commands. Access tokens. Personal messages.

Storing all of that on disk seemed like a bad security decision. So I decided to use RAM to store the history so the lifetime is limited to restarts. I used a fixed-size circular ring buffer with a hard limit of 50 entries.

The second question was IPC. There are many ways to do this on Linux. I chose UNIX Domain Sockets using AF_UNIX. The socket is created with restrictive permissions 0600. So it is not treated like a public service.

I followed a daemon/client model. The daemons job is to keep the clipboard alive and the client can ask the daemon to do something using its APIs. For example:

$ clipboard list
$ clipboard get 3
$ clipboard paste 3
$ clipboard clear

The final architecture

After the first round of design, the system looked like this:

Here, rofi is a quick simple gui pop-up tool that I used to spawn a pop-up to select the text from the history that needs to be pasted.

Next

Now let me dive deeper into the technicalities and my learnings. (Big DUMP incoming!!!)

Clipboard history - Understanding the X11 ownership model
Home/Projects/Clipboard History for Linux/Clipboard history - Understanding the X11 ownership model Learning about X11 and The In-Memory Ring Buffer I knew what I wanted: Detect when the user copies something get the text and store it. Now, I had to understand how will I put this into code and what tools and libraries are at my disposal. My first approach was very simple. I thought the clipboard could be checked like a variable. I imagined the clipboard as a variable that I could check again and again. It felt like an approach.
2026/09/22 · Projects / Clipboard History for Linux
Clipboard History - Ipc and Kernel Input
Home/Projects/Clipboard History for Linux/Clipboard History - Ipc and Kernel Input Building Kernel Keystroke Injection and IPC Security At this point, I needed to solve two different problems: How does the CLI safely tell the daemon what to do? How does the daemon make the active application actually receive the paste? The first problem taught me more about UNIX sockets. The second took me to /dev/uinput.
2026/09/22 · Projects / Clipboard History for Linux
Clipboard History - Systemd and Packaging
Home/Projects/Clipboard History for Linux/Clipboard History - Systemd and Packaging From a C Program to a Linux Utility Making the daemon start automatically I did not want to run ./clipd & every time I logged into Ubuntu. I wanted the daemon to behave like a normal background service. Since this is a user application, I used a systemd user service.
2026/09/22 · Projects / Clipboard History for Linux