---
name: "tty"
section: "4"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/tty/4"
---

# tty(4)

controlling terminal

## 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)](/ioctl/2.md) requests supported by the device that **tty** refers to, the [**ioctl**(2)](/ioctl/2.md) request **TIOCNOTTY** is supported.

### 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)](/ioctl/2.md) 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)](/chown/1.md), [**mknod**(1)](/mknod/1.md), [**ioctl**(2)](/ioctl/2.md), [**ioctl\_console**(2)](/ioctl_console/2.md), [**ioctl\_tty**(2)](/ioctl_tty/2.md), [**termios**(7)](/termios/7.md), [**ttyS**(4)](/ttyS/4.md), [**vcs**(4)](/vcs/4.md), [**pty**(7)](/pty/7.md), [**agetty**(8)](/agetty/8.md), [**mingetty**(8)](/mingetty/8.md)