xlabel

• This only works for systems that are using the X window system (most linux distributions and *BSD systems).

What

Label any window, and manage windows using labels.

Usage

To get help for the xlabel command, type xlabel -h in your terminal.

• You can only have one label for each window.

Installation

• Make sure you have xdotool installed.
• xlabel is just a shell script, so just download it, make it executable and run it.

Why

I needed a way to quickly switch between windows of the same application, but it may be used for other use cases too.

Why don't you use the window's title for that?

Because two windows can both have the same or similar title, but not belong to the same application.

Why don't you use the window's class name for that?

That works fine for graphical applications, but it doesn't work for terminal applications.