whence [ -acpv ] name ...
          For each name, indicate how it would be interpreted  if
          used  as  a  command name.  The -v flag produces a more
          verbose report.  The -p flag does  a  path  search  for
          name even if it is a shell function, alias, or reserved
          word.  The -c flag prints the  results  in  a  csh-like
          format.   The  -a flag does a search for all occurences
          of name throughout the command path.

     which
          Same as whence -c.