source: vendor/bash/3.1-p17/examples/loadables/tty.c

/* tty - return terminal name */

/* See Makefile for compilation details. */

#include "config.h"

#include <stdio.h>
#include "builtins.h"
#include "shell.h"
#include "bashgetopt.h"

extern char *ttyname ();

tty_builtin (list)
     WORD_LIST *list;
{
  int opt, sflag;
  char *t;

  reset_internal_getopt ();
  sflag = 0;
  while ((opt = internal_getopt (list, "s")) != -1)
    {
      switch (opt)
        {
        case 's':
          sflag = 1;
          break;
        default:
          builtin_usage ();
          return (EX_USAGE);
        }
    }
  list = loptend;

  t = ttyname (0);
  if (sflag == 0)
    puts (t ? t : "not a tty");
  return (t ? EXECUTION_SUCCESS : EXECUTION_FAILURE);
}

char *tty_doc[] = {
        "tty writes the name of the terminal that is opened for standard",
        "input to standard output.  If the `-s' option is supplied, nothing",
        "is written; the exit status determines whether or not the standard",
        "input is connected to a tty.",
        (char *)NULL
};

/* The standard structure describing a builtin command.  bash keeps an array
   of these structures. */
struct builtin tty_struct = {
        "tty",                  /* builtin name */
        tty_builtin,            /* function implementing the builtin */
        BUILTIN_ENABLED,        /* initial flags for builtin */
        tty_doc,                /* array of long documentation strings. */
        "tty [-s]",             /* usage synopsis; becomes short_doc */
        0                       /* reserved for internal use */
};