tty(1)

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

     SYNOPSIS
          tty [-s] [--silent] [--quiet] [--help] [--version]

     DESCRIPTION
          This documentation is no longer being maintained and may be
          inaccurate or incomplete.  The Texinfo documentation is now
          the authoritative source.

          This manual page documents the GNU version of tty.  tty
          prints the file name of the tty connected to its standard
          input.  It prints `not a tty' if the standard input is not a
          tty. Its exit status is:
          0 if the standard input is a tty
          1 if the standard input is not a tty
          2 if given incorrect arguments
          3 if a write error occurs

        OPTIONS
          --help
               Print a usage message on standard output and exit
               successfully.

          -s, --silent, --quiet
               Print nothing; only return an exit status.

          --version
               Print version information on standard output then exit
               successfully.