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PTY(3)		       FreeBSD Library Functions Manual			PTY(3)

NAME
     openpty, forkpty -- auxiliary functions to	obtain a pseudo-terminal

LIBRARY
     System Utilities Library (libutil,	-lutil)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/ioctl.h>
     #include <termios.h>
     #include <libutil.h>

     int
     openpty(int *amaster, int *aslave,	char *name, struct termios *termp,
	 struct	winsize	*winp);

     int
     forkpty(int *amaster, char	*name, struct termios *termp,
	 struct	winsize	*winp);

DESCRIPTION
     The function openpty() attempts to	obtain the next	available pseudo-ter-
     minal from	the system (see	pty(4)).  If it	successfully finds one,	it
     subsequently tries	to change the ownership	of the slave device to the
     real UID of the current process, the group	membership to the group
     ``tty'' (if such a	group exists in	the system), the access	permissions
     for reading and writing by	the owner, and for writing by the group, and
     to	invalidate any current use of the line by calling revoke(2).

     If	the argument name is not NULL, openpty() copies	the pathname of	the
     slave pty to this area.  The caller is responsible	for allocating the
     required space in this array.

     If	the arguments termp or winp are	not NULL, openpty() initializes	the
     termios and window	size settings from the structures these	arguments
     point to, respectively.

     Upon return, the open file	descriptors for	the master and slave side of
     the pty are returned in the locations pointed to by amaster and aslave,
     respectively.

     The forkpty() function first calls	openpty() to obtain the	next available
     pseudo-terminal from the system.  Upon success, it	forks off a new
     process.  In the child process, it	closes the descriptor for the master
     side of the pty, and calls	login_tty(3) for the slave pty.	 In the	parent
     process, it closes	the descriptor for the slave side of the pty.  The
     arguments amaster,	name, termp, and winp have the same meaning as
     described for openpty().

RETURN VALUES
     The openpty() function returns 0 on success, or -1	on failure.

     The forkpty() function returns -1 on failure, 0 in	the slave process, and
     the process ID of the slave process in the	parent process.

ERRORS
     On	failure, openpty() will	set the	global variable	errno to ENOENT.

     In	addition to this, forkpty() may	set it to any value as described for
     fork(2).

SEE ALSO
     chmod(2), chown(2), fork(2), getuid(2), open(2), revoke(2), login_tty(3),
     pty(4), termios(4), group(5)

BUGS
     The calling process must have an effective	UID of super-user in order to
     perform all the intended actions.	No notification	will occur if
     openpty() or forkpty() failed to proceed with one of the described	steps,
     as	long as	they could at least allocate the pty at	all (and create	the
     new process in the	case of	forkpty()).

FreeBSD	10.1		       December	29, 1996		  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | BUGS

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