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

NAME
     pty -- old-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 before it was	replaced by
     pts(4).  This traditional naming is still used in Linux.  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, and for
     running Linux binaries.

FILES
     The BSD-style compatibility pseudo-terminal driver	uses the following de-
     vice 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	13.0		       October 28, 2019			  FreeBSD 13.0

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

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