/* tee.c - Dual output                   */
/* Sends output to a file and to stdout  */
/* ABZ 13/07/1990                        */

#include <stdio.h>
#define STDERR 2

main(ac,av)
unsigned ac;
char *av[];
{
  FILE *f_ptr;
  unsigned here;
  unsigned c;
  char *out;

  out="a";
  here=1;
  if (av[here][0]=='-') {
    if (av[here][1]!='w')
      err_exit(av[0]); /* No options */
    out="w"; here++;
  }
  if (ac< 2 || ac != here+1) err_exit(av[0]); /* Wrong num. of params */
  f_ptr=fopen(av[here],out);
  if (f_ptr==NULL) {
    perror(av[here]); /* report error */
    exit(1);
  }
  while((c=getchar()) != EOF) {
    putchar(c);
    putc(c,f_ptr);
  }
  fclose(f_ptr);
} 

err_exit(s)
char *s;
{ 
  pr_error("Usage: "); pr_error(s);
  pr_error(" [-w] <filename>\n");
  exit(1);
}

pr_error(s) /* Writes string to error output */
char *s;
{
  write (STDERR,s,strlen(s));
}