man4/tty.4

   1 .\" Copyright (c) 1993 Michael Haardt (michael@moria.de), Fri Apr  2 11:32:09 MET DST 1993
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  23 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
  24 .\" Modified 2003-04-07 by Michael Kerrisk
  25 .\"
  26 .TH TTY 4 2003-04-07 "Linux" "Linux Programmer's Manual"
  27 .SH NAME
  28 tty \- controlling terminal
  29 .SH DESCRIPTION
  30 The file \fI/dev/tty\fP is a character file with major number 5 and
  31 minor number 0, usually of mode 0666 and owner.group root.tty.
  32 It is a synonym for the controlling terminal of a process, if any.
  33 .LP
  34 In addition to the
  35 .BR ioctl (2)
  36 requests supported by the device that
  37 \fBtty\fP refers to, the
  38 .BR ioctl (2)
  39 request \fBTIOCNOTTY\fP is supported.
  40 .SS TIOCNOTTY
  41 Detach the current process from its controlling terminal.
  42 .sp
  43 If the process is the session leader,
  44 then SIGHUP and SIGCONT signals are sent to the foreground process group
  45 and all processes in the current session lose their controlling tty.
  46 .sp
  47 This
  48 .BR ioctl (2)
  49 call only works on file descriptors connected
  50 to \fI/dev/tty\fP.
  51 It is used by daemon processes when they are invoked
  52 by a user at a terminal.
  53 The process attempts to open \fI/dev/tty\fP.
  54 If the open succeeds, it
  55 detaches itself from the terminal by using \fBTIOCNOTTY\fP, while if the
  56 open fails, it is obviously not attached to a terminal and does not need
  57 to detach itself.
  58 .SH FILES
  59 /dev/tty
  60 .SH "SEE ALSO"
  61 .BR chown (1),
  62 .BR mknod (1),
  63 .BR ioctl (2),
  64 .BR termios (3),
  65 .BR console (4),
  66 .BR ttyS (4),
  67 .BR mingetty (8)