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tty(4) [redhat man page]

TTY(4)							     Linux Programmer's Manual							    TTY(4)

NAME
tty - controlling terminal DESCRIPTION
The file /dev/tty is a character file with major number 5 and minor number 0, usually of mode 0666 and owner.group root.tty. It is a syn- onym for the controlling terminal of a process, if any. In addition to the ioctl() requests supported by the device that tty refers to, the following ioctl() request is supported: TIOCNOTTY Detach the current process from its controlling terminal, and remove it from its current process group, without attaching it to a new process group (that is, set its process group ID to zero). This ioctl() call only works on file descriptors connected to /dev/tty; this 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
mknod(1), chown(1), getty(1), termios(3), console(4), ttys(4) Linux 1992-01-21 TTY(4)

Check Out this Related Man Page

OPENPTY(3)						   BSD Library Functions Manual 						OPENPTY(3)

NAME
openpty, login_tty, forkpty -- tty utility functions SYNOPSIS
#include <util.h> int openpty(int *amaster, int *aslave, char *name, struct termios *termp, struct winsize *winp); int login_tty(int fd); pid_t forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp); DESCRIPTION
The openpty(), login_tty(), and forkpty() functions perform manipulations on ttys and pseudo-ttys. The openpty() function allocates a pseudo-tty and returns file descriptors for the master and slave in amaster and aslave. If name is non- null, the filename of the slave is returned in name. If termp is non-null, the terminal parameters of the slave will be set to the values in termp. If winp is non-null, the window size of the slave will be set to the values in winp. The login_tty() function prepares for a login on the tty fd (which may be a real tty device, or the slave of a pseudo-tty as returned by openpty()) by creating a new session, making fd the controlling terminal for the current process, setting fd to be the standard input, out- put, and error streams of the current process, and closing fd. The forkpty() function combines openpty(), fork(), and login_tty() to creates a new process operating in a pseudo-tty. The file descriptor of the master side of the pseudo-tty is returned in amaster, and the filename of the slave in name if it is non-null. The termp and winp parameters, if non-null, will determine the terminal attributes and window size of the slave side of the pseudo-tty. RETURN VALUES
If a call to openpty(), login_tty(), or forkpty() is not successful, -1 is returned and errno is set to indicate the error. Otherwise, openpty(), login_tty(), and the child process of forkpty() return 0, and the parent process of forkpty() returns the process ID of the child process. ERRORS
openpty() will fail if: [EAGAIN] There are no available pseudo-ttys. login_tty() will fail if ioctl() fails to set fd to the controlling terminal of the current process. forkpty() will fail if either openpty() or fork() fails. FILES
/dev/ptmx cloning pseudo-tty device /dev/ttys[0-9][0-9][0-9] slave pseudo-tty devices SEE ALSO
fork(2) BSD
April 5, 2008 BSD

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