whereis is used for locating a file’s binary, source and its associated man page, in Unix and Linux.
It is easy to use and displays a short output:
$ whereis bash
bash: /bin/bash /etc/bash.bashrc /usr/share/man/man1/bash.1.gz
If you need to find out only the associated man page/section, use whereis -m:
$ whereis -m bash
For displaying the file’s binaries, use the -b argument:
$ whereis -b vim
vim: /usr/bin/vim /usr/bin/vim.basic /usr/bin/vim.tiny /etc/vim /usr/share/vim
whereis -m is usefull when you need to find the man sections of a configuration file or C function (example: /etc/passwd or printf) because this types of files usually have two man sections.
$ whereis -m passwd
passwd: /usr/share/man/man1/passwd.1ssl.gz /usr/share/man/man1/passwd.1.gz /usr/share/man/man5/passwd.5.gz
So, we can find info about the /etc/passwd file in both the 1st and the 5th man sections:
$ man passwd
$ man 5 passwd