execute a simple command
-v     (On systems supporting the User Portability Utilities option.) Write a string to  standard  output
       that  indicates  the  pathname  or  command  that  will be used by the shell, in the current shell
       execution environment (see Shell Execution Environment ),  to  invoke  command_name,  but  do  not
       invoke command_name.

        * Utilities,  regular  built-in  utilities,  command_names  including  a slash character, and any
          implementation-defined functions that are found  using  the  PATH  variable  (as  described  in
          Command Search and Execution ), shall be written as absolute pathnames.

        * Shell  functions,  special built-in utilities, regular built-in utilities not associated with a
          PATH search, and shell reserved words shall be written as just their names.

        * An alias shall be written as a command line that represents its alias definition.

        * Otherwise, no output shall be written and the exit status shall reflect that the name  was  not
          found.
source manpages: command