1 /* tty -- print the name of the terminal connected to standard input
2 Copyright (C) 1990-2023 Free Software Foundation, Inc.
3
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 /* Displays "not a tty" if stdin is not a terminal.
18 Displays nothing if -s option is given.
19 Exit status 0 if stdin is a tty, 1 if not a tty, 2 if usage error,
20 3 if write error.
21
22 Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
23
24 #include <config.h>
25 #include <stdio.h>
26 #include <getopt.h>
27 #include <sys/types.h>
28
29 #include "system.h"
30 #include "quote.h"
31
32 /* Exit statuses. */
33 enum
34 {
35 TTY_STDIN_NOTTY = 1,
36 TTY_FAILURE = 2,
37 TTY_WRITE_ERROR = 3
38 };
39
40 /* The official name of this program (e.g., no 'g' prefix). */
41 #define PROGRAM_NAME "tty"
42
43 #define AUTHORS proper_name ("David MacKenzie")
44
45 /* If true, return an exit status but produce no output. */
46 static bool silent;
47
48 static struct option const longopts[] =
49 {
50 {"silent", no_argument, nullptr, 's'},
51 {"quiet", no_argument, nullptr, 's'},
52 {GETOPT_HELP_OPTION_DECL},
53 {GETOPT_VERSION_OPTION_DECL},
54 {nullptr, 0, nullptr, 0}
55 };
56
57 void
usage(int status)58 usage (int status)
59 {
60 if (status != EXIT_SUCCESS)
61 emit_try_help ();
62 else
63 {
64 printf (_("Usage: %s [OPTION]...\n"), program_name);
65 fputs (_("\
66 Print the file name of the terminal connected to standard input.\n\
67 \n\
68 -s, --silent, --quiet print nothing, only return an exit status\n\
69 "), stdout);
70 fputs (HELP_OPTION_DESCRIPTION, stdout);
71 fputs (VERSION_OPTION_DESCRIPTION, stdout);
72 emit_ancillary_info (PROGRAM_NAME);
73 }
74 exit (status);
75 }
76
77 int
main(int argc,char ** argv)78 main (int argc, char **argv)
79 {
80 int optc;
81
82 initialize_main (&argc, &argv);
83 set_program_name (argv[0]);
84 setlocale (LC_ALL, "");
85 bindtextdomain (PACKAGE, LOCALEDIR);
86 textdomain (PACKAGE);
87
88 initialize_exit_failure (TTY_WRITE_ERROR);
89 atexit (close_stdout);
90
91 silent = false;
92
93 while ((optc = getopt_long (argc, argv, "s", longopts, nullptr)) != -1)
94 {
95 switch (optc)
96 {
97 case 's':
98 silent = true;
99 break;
100
101 case_GETOPT_HELP_CHAR;
102
103 case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
104
105 default:
106 usage (TTY_FAILURE);
107 }
108 }
109
110 if (optind < argc)
111 {
112 error (0, 0, _("extra operand %s"), quote (argv[optind]));
113 usage (TTY_FAILURE);
114 }
115
116 errno = ENOENT;
117
118 if (silent)
119 return isatty (STDIN_FILENO) ? EXIT_SUCCESS : TTY_STDIN_NOTTY;
120
121 int status = EXIT_SUCCESS;
122 char const *tty = ttyname (STDIN_FILENO);
123
124 if (! tty)
125 {
126 tty = _("not a tty");
127 status = TTY_STDIN_NOTTY;
128 }
129
130 puts (tty);
131 return status;
132 }
133