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  interface.   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 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 nonexistent master device will already cause a new master device node  to
       be created.  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.

Debian                                          October 28, 2019                                          PTY(4)