Definition - What does Plan File mean?
In Unix, a plan file (".plan") is a text file that contains information about a user. The name ".plan" is actually the filename not the file extension. The file is located in the user's home directory and is the file opened by the "finger" command when someone checks the profile of another user.
Techopedia explains Plan File
Unix is a multitasking and multi-user operating system. A user can obtain information about another user by running the “finger” command. The command looks for the ".plan" file in the latter's home directory and displays its contents if it finds it. If there is no such file, the message “no plan” is displayed instead.
The contents of a plan file are actually user supplied. Some users, instead of putting basic information in their ".plan" file, store ASCII art in it instead. ASCII art is a graphic or presentation drawn using printable ASCII characters.