DBus (Desktop Bus) is a message bus system, which allows communication between multiple applications on a system. It's commonly used in Linux-based systems for inter-process communication (IPC) and is a popular alternative to traditional IPC mechanisms such as pipes and sockets. In terms of process control, DBus can be used to send messages between processes to initiate actions, exchange information, or trigger events. For example, a process can use DBus to request another process to perform a task, and the second process can send a message back indicating the status of the task. This enables the creation of complex systems in which multiple processes interact and collaborate to perform their respective tasks. DBus also provides a system for communication between different user sessions, making it possible for processes running in different user accounts to communicate with each other. This is particularly useful in the context of multi-user systems, such as servers. Overall, DBus is a powerful tool for inter-process communication and process control in Linux-based systems.