http://www.unixmen.com/learn-man-vim-editor-file-globbing-rhcsa/

man -k <cmd>
    search comman names and short-descriptions for <cmd>
    
Section 1 user commands
section 2 system calls
section 3 library functions
section 4 special files
section 5 file formats
section 6 games
section 7 protocols and file systems
section 8 administrative commands
section 9 internal kernel API