.7 File Extension
What is a 7 file?
A 7 file is a Unix manual page (man page) that can be accessed using the man utility. It describes a miscellaneous piece of system information. For example, the file boot.7 describes the system boot process.
Man pages are system-level documentation that describes the inner workings of a Unix-like operating system. These pages are typically grouped into sections that contain a related set of documentation.
The seventh section of most Unix manuals, however, contains miscellaneous important pieces of information that do not fit neatly into the manual's other seven categories. Each page of that section is saved as a 7 file.
How to open a 7 file
In Unix-like OSes, you can open a 7 file by calling the man utility using the name of the file. For example, to open boot.7, enter man boot(7).