.8 File Extension
What is an 8 file?
An 8 file contains a Unix manual page (man page) that describes an admin-level command. Each 8 file is named for the command it documents. 8 files are meant to be opened and viewed using the Unix man utility.
Unix-like OSes typically contain a user manual divided into eight sections. The final section of this manual describes system-administration commands, daemons, and hardware-related commands. Each page of the manual is saved as a separate 8 file, named for the command it describes.
For example, the file shutdown.8 contains documentation related to the shutdown command. It includes a quick overview of how to use the command, a detailed description of the command, a list of command-level options, and other related information.
How to open an 8 file
In Unix-like OSes, you can open an 8 file by calling the man utility using the name of the file. For example, to open shutdown.8, enter man shutdown(8).