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)

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