pty(7) pty(7)NAME pty - pseudo terminal driver DESCRIPTION The pty 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 dev- ice provides processes an interface identical to that described in termio(7). However, whereas all other devices which provide the interface described in termio(7) 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 writ- ten on the master device is given to the slave device as in- put and anything written on the slave device is presented as input on the master device. The following ioctl 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 refer- ence) a zero parameter. When applied to the master side of a pseudo terminal, each subse- quent read 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 con- trol 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 as with (CONTROL-S). TIOCPKT_START whenever output to the terminal is restart- ed. TIOCPKT_DOSTOP whenever t_stopc is CONTROL-S and t_startc is CONTROL-Q. April, 1990 1
pty(7) pty(7)TIOCPKT_NOSTOP whenever the start and stop characters are not CONTROL-S/CONTROL-Q. This mode is used by rlogin(1N) and rlogind(1M) to implement a remote-echoed, locally CONTROL- S/CONTROL-Q flow-controlled remote login with proper back-flushing of output; it can be used by other similar programs. FILES /dev/pty[p-r][0-9a-f] /dev/tty[p-r][0-9a-f] BUGS It is not possible to send an EOT. 2 April, 1990