Arguments

 

command

   A pointer to a null-terminated string containing a shell command
   line.
 

type

   A pointer to a null-terminated string containing an I/O mode.
   Because open files are shared, you can use a type r command as
   an input filter and a type w command as an output filter. Specify
   one of the following values for the type argument:

   o  r-the calling program can read from the standard output of the
      command by reading from the returned file stream.

   o  w-the calling program can write to the standard input of the
      command by writing to the returned file stream.