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PTS(4) Kernel Interfaces Manual PTS(4) 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 identi- cal 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 manipulat- ing 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 any- thing written on the slave device is presented as input on the master de- vice. The following ioctl(2) calls apply only to pseudo-terminals: TIOCPKT Enable/disable packet mode. Packet mode is enabled by speci- fying (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 in- clusive-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 in- formation 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) func- tion 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 re- placed with the pts driver. FreeBSD ports 15.quarterly August 20, 2008 PTS(4)
NAME | DESCRIPTION | FILES | DIAGNOSTICS | SEE ALSO | HISTORY
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