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GRANTPT(3)	       FreeBSD Library Functions Manual		    GRANTPT(3)

NAME
     grantpt, ptsname, unlockpt, posix_openpt -- pseudo-terminal access	func-
     tions

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <stdlib.h>

     int
     grantpt(int fildes);

     char *
     ptsname(int fildes);

     int
     unlockpt(int fildes);

     #include <fcntl.h>

     int
     posix_openpt(int mode);

DESCRIPTION
     The grantpt(), ptsname(), unlockpt(), and posix_openpt() functions	allow
     access to pseudo-terminal devices.	 The first three functions accept a
     file descriptor that references the master	half of	a pseudo-terminal
     pair.  This file descriptor is created with posix_openpt().

     The grantpt() function is used to establish ownership and permissions of
     the slave device counterpart to the master	device specified with fildes.
     The slave device's	ownership is set to the	real user ID of	the calling
     process, and the permissions are set to user readable-writable and	group
     writable.	The group owner	of the slave device is also set	to the group
     ``tty'' if	it exists on the system; otherwise, it is left untouched.

     The ptsname() function returns the	full pathname of the slave device
     counterpart to the	master device specified	with fildes.  This value can
     be	used to	subsequently open the appropriate slave	after posix_openpt()
     and grantpt() have	been called.

     The unlockpt() function clears the	lock held on the pseudo-terminal pair
     for the master device specified with fildes.

     The posix_openpt()	function opens the first available master pseudo-ter-
     minal device and returns a	descriptor to it.  The mode argument specifies
     the flags used for	opening	the device:

     O_RDWR    Open for	reading	and writing.

     O_NOCTTY  If set, do not allow the	terminal to become the controlling
	       terminal	for the	calling	process.

RETURN VALUES
     The grantpt() and unlockpt() functions return the value 0 if successful;
     otherwise the value -1 is returned	and the	global variable	errno is set
     to	indicate the error.

     The ptsname() function returns a pointer to the name of the slave device
     on	success; otherwise a NULL pointer is returned and the global variable
     errno is set to indicate the error.

     The posix_openpt()	function returns a file	descriptor to the first	avail-
     able master pseudo-terminal device	on success; otherwise -1 is returned
     and the global variable errno is set to indicate the error.

ERRORS
     The grantpt(), ptsname(), and unlockpt() functions	may fail and set errno
     to:

     [EINVAL]		fildes is not a	master pseudo-terminal device.

     In	addition, the grantpt()	function may set errno to:

     [EACCES]		The slave pseudo-terminal device could not be
			accessed.

     The posix_openpt()	function may fail and set errno	to:

     [EINVAL]		mode consists of an invalid mode bit.

     [EAGAIN]		The system has no available pseudo-terminal devices.

     The grantpt(), ptsname(), and unlockpt() functions	may also fail and set
     errno for any of the errors specified for the fstat(2) system call.

     The posix_openpt()	function may also fail and set errno for any of	the
     errors specified for the open(2) system call.

SEE ALSO
     open(2), pty(4), tty(4)

STANDARDS
     The grantpt(), ptsname(), unlockpt(), and posix_openpt() functions	con-
     form to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY
     The grantpt(), ptsname(), unlockpt(), and posix_openpt() functions
     appeared in FreeBSD 5.0.

NOTES
     The purpose of the	unlockpt() function has	no meaning in FreeBSD.

     The flag O_NOCTTY is included for compatibility; in FreeBSD, opening a
     terminal does not cause it	to become a process's controlling terminal.

FreeBSD	10.1		       December	23, 2002		  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | NOTES

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