bionic (4) pts.4freebsd.gz

NAME

     pts — pseudo-terminal driver

DESCRIPTION

     The pts driver provides support for a device-pair termed a pseudo-terminal.  A pseudo-terminal is a pair of
     character devices, a master device and a slave device.  The slave device provides to a process an interface
     identical to that described in tty(4).  However, whereas all other devices which provide the interface
     described in tty(4) have a hardware device of some sort behind them, the slave device has, instead, another
     process manipulating it through the master half of the pseudo-terminal.  That is, anything written on the
     master device is given to the slave device as input and anything written on the slave device is presented
     as input on the master device.

     The following ioctl(2) calls apply only to pseudo-terminals:

     TIOCPKT       Enable/disable packet mode.  Packet mode is enabled by specifying (by reference) a nonzero
                   parameter and disabled by specifying (by reference) a zero parameter.  When applied to the
                   master side of a pseudo-terminal, each subsequent read(2) from the terminal will return data
                   written on the slave part of the pseudo-terminal preceded by a zero byte (symbolically
                   defined as TIOCPKT_DATA), or a single byte reflecting control status information.  In the
                   latter case, the byte is an inclusive-or of zero or more of the bits:

                   TIOCPKT_FLUSHREAD   whenever the read queue for the terminal is flushed.

                   TIOCPKT_FLUSHWRITE  whenever the write queue for the terminal is flushed.

                   TIOCPKT_STOP        whenever output to the terminal is stopped a la ‘^S’.

                   TIOCPKT_START       whenever output to the terminal is restarted.

                   TIOCPKT_DOSTOP      whenever VSTOP is ‘^S’ and VSTART is ‘^Q’.

                   TIOCPKT_NOSTOP      whenever the start and stop characters are not ‘^S/^Q’.

                   While this mode is in use, the presence of control status information to be read from the
                   master side may be detected by a select(2) for exceptional conditions.

                   This mode is used by rlogin(1) and rlogind(8) to implement a remote-echoed, locally ‘^S/^Q’
                   flow-controlled remote login with proper back-flushing of output; it can be used by other
                   similar programs.

     TIOCGPTN      Obtain device unit number, which can be used to generate the filename of the pseudo-terminal
                   slave device.  This ioctl(2) should not be used directly.  Instead, the ptsname(3) function
                   should be used.

     TIOCPTMASTER  Determine whether the file descriptor is pointing to a pseudo-terminal master device.  This
                   ioctl(2) should not be used directly.  It is used to implement routines like grantpt(3).

FILES

     The files used by this pseudo-terminals implementation are:

     /dev/pts/[num]  Pseudo-terminal slave devices.

DIAGNOSTICS

     None.

SEE ALSO

     posix_openpt(2), grantpt(3), ptsname(3), pty(4), tty(4)

HISTORY

     A pseudo-terminal driver appeared in 4.2BSD.  In FreeBSD 8.0, it was replaced with the pts driver.