nmdm(4) [freebsd man page]

NMDM(4) 						   BSD Kernel Interfaces Manual 						   NMDM(4)

NAME

     nmdm -- nullmodem terminal driver

SYNOPSIS

     device nmdm

DESCRIPTION

     The nmdm driver provides two tty(4) devices connected by a virtual ``null modem'' cable.

     If either of the two tty devices have the CDSR_OFLOW bit (``stty dsrflow'') set in their line discipline, the nmdm device will emulate the
     speed configured in the termios(4) settings.  The speed emulation works independently in the two directions, controlled by the slower end's
     termios settings (c_ispeed, c_ospeed, CS5 ... CS8, CSTOPB and PARENB).

FILES

     /dev/nmdmN[AB]  nullmodem device nodes.  Where the A node has a matching B node.

     The nmdm driver implements ``on-demand device creation'' so simply accessing a given instance in /dev will create it.

DIAGNOSTICS

     None.

SEE ALSO

     stty(1), termios(4), tty(4)

HISTORY

     The nmdm driver first appeared in FreeBSD 4.4.

BSD
								 January 27, 2005							       BSD

PTY(4)							   BSD Kernel Interfaces Manual 						    PTY(4)

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.

BSD
								  August 20, 2008							       BSD