tty(4) — Linux manual page


tty(4)                  Kernel Interfaces Manual                  tty(4)

NAME         top

       tty - controlling terminal

DESCRIPTION         top

       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

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

       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         top


SEE ALSO         top

       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         top

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Linux man-pages 6.9.1          2024-05-02                         tty(4)

Pages that refer to this page: screen(1)setterm(1)tset(1)ioctl(2)ioctl_console(2)open(2)stdin(3)ttyS(4)vcs(4)pty(7)termio(7)pam_selinux(8)