Stops output to a terminal (e.g. like typing ‘^S’). Takes no parameter.
TIOCSTART
Restarts output (stopped by TIOCSTOP or by typing ‘^S’). Takes no parameter.
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 t_stopc is ‘^S’ and t_startc 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.
TIOCUCNTL
Enable/disable a mode that allows a small number of simple user ioctl(2) commands to be passed through the pseudo-terminal, using a protocol similar to that of TIOCPKT. The TIOCUCNTL and TIOCPKT modes are mutually exclusive. This mode is enabled from the master side of a pseudo terminal by specifying (by reference) a nonzero parameter and disabled by specifying (by reference) a zero parameter. Each subsequent read(2) from the master side will return data written on the slave part of the pseudo terminal preceded by a zero byte, or a single byte reflecting a user control operation on the slave side. A user control command consists of a special ioctl(2) operation with no data; the command is given as UIOCCMD (n), where n is a number in the range 1-255. The operation value n will be received as a single byte on the next read(2) from the master side. The ioctl(2) UIOCCMD (0) is a no-op that may be used to probe for the existence of this facility. As with TIOCPKT mode, command operations may be detected with a select(2) for exceptional conditions.
