Which command is used to display the kernel ring buffer messages?

The command that is used to display the kernel ring buffer messages is "dmesg." This command retrieves and displays the messages that the kernel itself has logged, which can include information about system hardware, device drivers, and other kernel-level events that have occurred during startup and runtime.

The kernel ring buffer is an important resource for system administrators and developers, as it helps in diagnosing issues and understanding what is happening in the system from the kernel's perspective. The output from "dmesg" is often the first place to look when troubleshooting hardware issues, as it provides real-time insights into the interactions between the kernel and the various components of the hardware.

Other options, such as "init," "pstree," and "halt," serve different purposes. "init" is related to system initialization and does not provide information about kernel messages. "pstree" is used to display the processes in a tree format, which is useful for understanding process hierarchies but does not relate to kernel messages. "halt" is a command used to stop the system safely and does not display kernel messages either. Thus, for retrieving kernel ring buffer messages, "dmesg" is the appropriate command.