Getting an X11 Window from a Process ID: A Simple Guide
If you are a Linux user, you may have come across the term X11 window and process ID (PID) while trying to troubleshoot or monitor a running application. But what exactly are these and how do they relate to each other? In this guide, we will dive into the world of X11 windows and PIDs and learn how to get an X11 window from a process ID.
First, let's understand what an X11 window is. X11, also known as X Windows, is the standard windowing system for Unix-like operating systems. It provides a graphical user interface (GUI) for users to interact with their system. A window, in this context, refers to a rectangular area on the screen that displays the output of an application. Each window has a unique identifier known as the window ID, which is used to manipulate and retrieve information about the window.
Now, let's move on to process IDs. A process ID is a unique number assigned to a running process by the operating system. It is used to identify and manage the process. Every process in a Linux system has a unique PID, which can be accessed through various system commands.
So, why would you need to get an X11 window from a process ID? Well, there are several reasons. For instance, let's say you have an application running in the background, and you want to bring its window to the foreground. Or, you may want to get information about a specific window, such as its size or position on the screen. In such cases, knowing the process ID of the application can help you retrieve the window ID and perform the desired action.
Now, let's get to the actual process of getting an X11 window from a process ID. The first step is to find out the process ID of the application whose window you want to retrieve. This can be done using the `ps` command, which lists all running processes along with their PIDs. For example, if you want to get the window ID of the Firefox browser, you can run the command `ps -ef | grep firefox` to find its PID.
Once you have the process ID, you can use the `xwininfo` command to get information about the application's X11 window. This command takes the PID as an argument and displays a lot of information about the window, including its ID. The window ID is displayed under the "Window id" field, which is a hexadecimal number.
Now that you have the window ID, you can use it to manipulate the window using various X11 tools. For example, you can use the `xdotool` command to bring the window to the foreground by running `xdotool windowactivate <window ID>`.
In conclusion, getting an X11 window from a process ID is a simple process that can be useful in many situations. It allows you to interact with applications running in the background and perform actions on their windows. So, the next time you need to retrieve an X11 window, remember this guide and use the power of PIDs to your advantage.
