pts(4) [freebsd man page]
PTS(4) BSD 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 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 termi- nal 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. BSD
August 20, 2008 BSD
Check Out this Related Man Page
pty(4) Kernel Interfaces Manual pty(4) Name pty - pseudoterminal driver Syntax pseudo-device pty[n] Description The driver provides support for a device-pair termed a pseudoterminal. A pseudoterminal is a pair of character devices, a master device and a slave device. The slave device provides processes with an interface identical to that described in However, whereas all other devices that provide the interface described in have a hardware device of some sort behind them, the slave device has, instead, another process manipulating it through the master half of the pseudoterminal. 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 slave device can be opened multiple times, while the master half can be opened only once. If no optional n value is given defining the number of pseudoterminal pairs to be configured, 16 pseudoterminal pairs are configured. All pseudoterminal lines should have a corresponding entry in the /etc/ttys file. This must be done to insure that logins that use pseudoter- minals will be tracked in the utmp and wtmp files. The following calls apply only to pseudoterminals: TIOCSTOP Stops output to a terminal (for example, like typing CTRL/S). Takes no parameter. TIOCSTART Restarts output (stopped by TIOCSTOP or by typing CTRL/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 pseudoterminal, each subsequent from the terminal will return data written on the slave part of the pseudoterminal 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 by typing CTRL/S. TIOCPKT_START whenever output to the terminal is restarted. TIOCPKT_DOSTOP whenever the stop character is CTRL/S and the start character is CTRL/Q. TIOCPKT_NOSTOP whenever the start and stop characters are not CTRL/S and/or CTRL/Q. This mode is used by and to implement a remote-echoed, locally flow-controlled (using CTRL/S or CTRL/Q, or both) remote login with proper back-flushing of output. It can be used by other similar programs. TIOCREMOTE A mode for the master half of a pseudoterminal, independent of TIOCPKT. This mode causes input to the pseudoterminal to be flow controlled and not input edited (regardless of the terminal mode). Each write to the control terminal produces a record boundary for the process reading the terminal. In normal usage, a write of data is like the data typed as a line on the terminal; a write of 0 bytes is like typing an end-of-file character. TIOCREMOTE can be used when doing remote line editing in a window manager, or whenever flow-controlled input is required. TIOCMASTER Allows the master to have complete control over the pseudoterminal and causes the slave side to sleep until the master relinquishes control. This is useful in preventing changes on the pseudoterminal from going undetected and being reset by the master. Files (master pseudoterminals) (slave pseudoterminals) See Also tty(4), MAKEDEV(8) pty(4)