setbuf

 NAME
  setbuf - set alternative stream buffer

 SYNOPSIS
  #include <stdio.h>

  void setbuf(fp, buf);
  FILE *fp;
  char *buf;

 FUNCTION
  setbuf() changes the internal buffer used by stdio.  The buffer you
  pass it must be BUFSIZ bytes in size.  You can set a file pointer
  to unbuffered by passing NULL for your buffer.

  setvbuf() superceeds this call and is, in general, a better routine.

 NOTE
  refer to the file_pointer manual page for general information

                  !!

  if buffering is turned off for a file pointer representing a
  console device, the console device is set to unbuffered as well.

 EXAMPLE
  #include <stdio.h>

  main()
  {
      setbuf(stdout, NULL);

      printf("This will print immediately because");
      sleep(1);
      printf(" we are unbuffered");
      sleep(1);
      puts("");
      return(0);
  }

 INPUTS
  FILE *fp;       file pointer to rewind

  char *buf;      buffer the file pointer uses instead of its
              own or NULL to make the file pointer unbuffered.

 RESULTS
  none

 SEE ALSO
  setvbuf