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PTY(4)		       FreeBSD Kernel Interfaces Manual			PTY(4)

NAME
     pty -- BSD-style and System V-style compatibility pseudo-terminal driver

SYNOPSIS
     device pty

DESCRIPTION
     The pty driver provides support for the traditional BSD naming scheme
     that was used for accessing pseudo-terminals.  When the device /dev/ptyXX
     is	being opened, a	new terminal shall be created with the pts(4) driver.
     A device node for this terminal shall be created, which has the name
     /dev/ttyXX.

     The pty driver also provides a cloning System V /dev/ptmx device.

     New code should not try to	allocate pseudo-terminals using	this inter-
     face.  It is only provided	for compatibility with older C libraries that
     tried to open such	devices	when posix_openpt(2) was being called.

FILES
     The BSD-style compatibility pseudo-terminal driver	uses the following
     device names:

     /dev/pty[l-sL-S][0-9a-v]  Pseudo-terminal master devices.

     /dev/tty[l-sL-S][0-9a-v]  Pseudo-terminal slave devices.

     /dev/ptmx		       Control device, returns a file descriptor to a
			       new master pseudo-terminal when opened.

DIAGNOSTICS
     None.

SEE ALSO
     posix_openpt(2), pts(4), tty(4)

HISTORY
     A pseudo-terminal driver appeared in 4.2BSD.

BUGS
     Unlike previous implementations, the master and slave device nodes	are
     destroyed when the	PTY becomes unused.  A call to stat(2) on a nonexis-
     tent master device	will already cause a new master	device node to be cre-
     ated.  The	master device can only be destroyed by opening and closing it.

     The pty driver cannot be unloaded,	because	it cannot determine if it is
     being used.

FreeBSD	9.2			August 20, 2008			   FreeBSD 9.2

NAME | SYNOPSIS | DESCRIPTION | FILES | DIAGNOSTICS | SEE ALSO | HISTORY | BUGS

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