What does the -m option do in the whereis command?

As you just saw in the command whereis -bm python3, the -m option specifically tells the whereis command to search for manual pages (documentation).

Here is a quick breakdown:

• Its Purpose: It filters the search results to only show the locations of documentation files (usually found in directories like /usr/share/man).
• Why use it with -b? When you use -bm together, you are telling the system: "Show me exactly two things: where the binary (executable) is and where the manual (documentation) is."
• In your Python example: The -m part of the command was responsible for finding the path /usr/share/man/man1/python3.1.gz.

Without the -m (if you only used -b), the manual page location would have been hidden from your results!