#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/file.h>
#include <sys/ioctl.h>

#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif

extern const char *__progname;

static int ttyfd;

static void usage(void)
{
 fprintf(stderr,"Usage: %s [tty] 0|1   (uses stdout if no tty specified)\n",__progname);
 exit(1);
}

int main(int, char **);
int main(int ac, char **av)
{
 int ioc;
 const char *arg;
 const char *iocname;

 switch (ac)
  { default:
       usage();
       break;
    case 2:
       ttyfd = 1;
       arg = av[1];
       break;
    case 3:
       ttyfd = open(av[1],O_RDWR|O_NDELAY|O_NOCTTY,0);
       if (ttyfd < 0)
	{ fprintf(stderr,"%s: %s: %s\n",__progname,av[1],strerror(errno));
	  exit(1);
	}
       arg = av[2];
       break;
  }
 if (!strcmp(arg,"0"))
  { ioc = TIOCCDTR;
    iocname = "TIOCCDTR";
  }
 else if (!strcmp(arg,"1"))
  { ioc = TIOCSDTR;
    iocname = "TIOCSDTR";
  }
 else
  { usage();
  }
 if (ioctl(ttyfd,ioc,0) < 0)
  { fprintf(stderr,"%s: %s: %s\n",__progname,iocname,strerror(errno));
    exit(1);
  }
 exit(0);
}