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NAME

     pty -- BSD-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.

     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.

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.

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 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.