xprop

xprop is a utility for the X Window System that allows users to inspect and modify properties of X windows and their applications. It can display the name, class, and other attributes of a window, as well as any custom properties that have been set. This information can be useful for debugging X applications, automating tasks, or simply understanding how the X Window System works.

To use xprop, you typically run it from a terminal, and then click on the window you want to inspect. xprop will then print a list of properties associated with that window to the standard output. Properties are displayed as a series of name-value pairs. The names are often cryptic strings representing internal identifiers, while the values can be of various data types, including strings, integers, and lists.

xprop can also be used to set or modify window properties. This is done by providing the property name and the desired value as arguments on the command line. For example, one might use xprop to change the title of a window or to set a custom property for a specific application. However, modifying properties can sometimes lead to unexpected behavior if not done carefully, and it's generally recommended to understand the implications before making changes.

This tool is particularly helpful for developers and system administrators who need to interact with the X Window System at a deeper level. It provides a direct way to query and manipulate the underlying data structures that govern window behavior and appearance within the X environment.