Question

man 3p printf
man 3 printf

The above two man page gives different info of printf.

What’s different for man 3 and man 3p?

Answer 1

$ man -k printf | grep '^printf'
printf (1)           - format and print data
printf (1posix)      - write formatted output
printf (3)           - formatted output conversion
printf (3posix)      - print formatted output

You have probably installed the manpages-posix and manpages-posix-dev packages on your system, as I have. This also gives you the POSIX-prepared manpages, which is an excellent way to determine if you’re relying on behavior specific to your system or standardized behavior.