The meaning of the number displayed on the man page in Linux

0     Header files
0p    Header files (POSIX)
1     Executable programs or shell commands
1p    Executable programs or shell commands (POSIX)
2     System calls (functions provided by the kernel)
3     Library calls (functions within program libraries)
3n    Network Functions
3p    Perl Modules
4     Special files (usually found in /dev)
5     File formats and conventions eg /etc/passwd
6     Games
7     Miscellaneous  (including  macro  packages and conventions), e.g. man(7), groff(7)
8     System administration commands (usually only for root)
9     Kernel routines
l     Local documentation
n     New manpages