TTY(4)                    (2019-03-06)                     TTY(4)

     NAME
          tty - controlling terminal

     DESCRIPTION
          The file /dev/tty is a character file with major number 5
          and minor number 0, usually with mode 0666 and ownership
          root:tty.  It is a synonym for the controlling terminal of a
          process, if any.

          In addition to the ioctl(2) requests supported by the device
          that tty refers to, the ioctl(2) request TIOCNOTTY is sup-
          ported.

        TIOCNOTTY
          Detach the calling process from its controlling terminal.

          If the process is the session leader, then SIGHUP and
          SIGCONT signals are sent to the foreground process group and
          all processes in the current session lose their controlling
          tty.

          This ioctl(2) call works only on file descriptors connected
          to /dev/tty. It is used by daemon processes when they are
          invoked by a user at a terminal.  The process attempts to
          open /dev/tty. If the open succeeds, it detaches itself from
          the terminal by using TIOCNOTTY, while if the open fails, it
          is obviously not attached to a terminal and does not need to
          detach itself.

     FILES
          /dev/tty

     SEE ALSO
          chown(1), mknod(1), ioctl(2), ioctl_console(2),
          ioctl_tty(2), termios(3), ttyS(4), vcs(4), pty(7),
          agetty(8), mingetty(8)

     COLOPHON
          This page is part of release 5.10 of the Linux man-pages
          project.  A description of the project, information about
          reporting bugs, and the latest version of this page, can be
          found at https://www.kernel.org/doc/man-pages/.

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