Final answer:
The dmesg command displays the kernel log messages in Linux and Unix-based operating systems. It helps in troubleshooting hardware, device driver, and system performance issues.
Step-by-step explanation:
The dmesg command is a command-line utility in Linux and Unix-based operating systems that displays the kernel ring buffer messages. It shows the log messages generated by the kernel during the boot process and while the system is running. The kernel log messages contain information about system hardware, device drivers, and any errors or warnings.
For example, if there is a hardware issue or a driver problem, the dmesg command can provide valuable information for troubleshooting. By analyzing the kernel log messages, system administrators and users can identify and resolve issues that may be affecting the system's performance.
Therefore, option 3) Kernel log messages is the correct answer. The dmesg command does not show user login logoff attempts, which would be logged in separate log files such as auth.log, and it does not display the syslog file for info messages by default.