From LQWiki

NAME tty - print the file name of the terminal connected to standard input

SYNOPSIS
tty [OPTION]...

DESCRIPTION
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

AUTHOR
       Written by David MacKenzie.

REPORTING BUGS
       Report bugs to <bug-coreutils a-t- gnu dot org>.

COPYRIGHT
       Copyright © 2002 Free Software Foundation, Inc.
       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR	 A  PARTICULAR
       PURPOSE.

SEE ALSO
The  full  documentation for tty is maintained as a Texinfo manual.  If the info and tty programs are properly installed at your site, the command

      info tty

should give you access to the complete manual.