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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.