When is useful use "silent" for tty?

Manuel_Jordan · September 17, 2023, 4:10pm

If the tty --help command is executed it shows

tty --help
Usage: tty [OPTION]...
Print the file name of the terminal connected to standard input.

  -s, --silent, --quiet   print nothing, only return an exit status
      --help     display this help and exit
      --version  output version information and exit

Therefore when tty -s is executed it returns nothing

Question

When is useful use silent for tty?

pdecker · September 17, 2023, 4:59pm

I thought maybe in a script it would not show any output but the return code would contain the value it would normally show. I tested that but it doesn’t. Just shows a 0 return.

tty -s
echo “$?”
0

nevj · September 18, 2023, 2:38am

Hi Manuel,
I looked at the source code

github.com

wertarbyte/coreutils/blob/master/src/tty.c

/* tty -- print the name of the terminal connected to standard input
   Copyright (C) 1990-2005, 2008-2010 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Displays "not a tty" if stdin is not a terminal.
   Displays nothing if -s option is given.
   Exit status 0 if stdin is a tty, 1 if not, 2 if usage error,
   3 if write error.

This file has been truncated. show original

It does indeed display nothing with the -s option.
but i think it returns 0 if the terminal is a tty
and 1 if the terminal is not a tty

however @pdecker tried it and it returned zero… does that mean he was using a tty terminal?
I am not sure
Regards
Neville

In Termux

$ tty -s
$ echo "$?"
0
$ tty
/dev/pts/0

So it thinks /dev/pts0 is a tty ??

Manuel_Jordan · September 18, 2023, 11:13pm

Hello to all.

Pls let me try your suggestions in both environments, GUI and server.

I am using the Window Terminal available by default on Ubuntu Desktop and Fedora Workstation. So not server environment, but it is going to be test it.

Best to all.