tiocgpkt(2const) - BetterMan

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TIOCPKT	Enable (when *mode is nonzero) or disable packet mode. Can be applied to the master side of a pseudoterminal only (and will return ENOTTY otherwise). In packet mode, each subsequent read(2) will return a packet that either contains a single nonzero control byte, or has a single byte containing zero ('\0') followed by data written on the slave side of the pseudoterminal. If the first byte is not TIOCPKT_DATA (0), it is an OR of one or more of the following bits:
TIOCGPKT	Return the current packet mode setting in the integer pointed to by mode.
TIOCSPTLCK	Set (if lock is nonzero) or remove (if lock is zero) the lock on the pseudoterminal slave device. (See also unlockpt(3).)
TIOCGPTLCK	Place the current lock state of the pseudoterminal slave device in the location pointed to by lock.
TIOCGPTPEER	Given a file descriptor in fd that refers to a pseudoterminal master, open (with the given open(2)-style flags) and return a new file descriptor that refers to the peer pseudoterminal slave device. This operation can be performed regardless of whether the pathname of the slave device is accessible through the calling process's mount namespace.
TIOCGPKT	Linux 3.8.
TIOCGPTLCK	Linux 3.8.
TIOCGPTPEER	Linux 4.13.

NAME

TIOCPKT, TIOCGPKT, TIOCSPTLCK, TIOCGPTLCK, TIOCGPTPEER - pseudoterminal ioctls

Standard C library (libc, -lc)

bash

#include <asm/termbits.h>\n  /* Definition of \nTIOC*\n constants */
\n#include <sys/ioctl.h>

bash

int ioctl(int \nfd\n, TIOCPKT, const int *\nmode\n);\n
\nint ioctl(int \nfd\n, TIOCPKT, int *\nmode\n);

bash

int ioctl(int \nfd\n, TIOCSPTLCK, const int *\nlock\n);\n
\nint ioctl(int \nfd\n, TIOCGPTLCK, int *\nlock\n);

bash

int ioctl(int \nfd\n, TIOCGPTPEER, int \nflags\n);

TIOCPKT: Enable (when *mode is nonzero) or disable packet mode. Can be applied to the master side of a pseudoterminal only (and will return ENOTTY otherwise). In packet mode, each subsequent read(2) will return a packet that either contains a single nonzero control byte, or has a single byte containing zero ('\0') followed by data written on the slave side of the pseudoterminal. If the first byte is not TIOCPKT_DATA (0), it is an OR of one or more of the following bits:

: TIOCPKT_FLUSHREAD The read queue for the terminal is flushed.
TIOCPKT_FLUSHWRITE The write queue for the terminal is flushed.
TIOCPKT_STOP Output to the terminal is stopped.
TIOCPKT_START Output to the terminal is restarted.
TIOCPKT_DOSTOP The start and stop characters are ^S / ^Q .
TIOCPKT_NOSTOP The start and stop characters are not ^S / ^Q .
: While packet 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 or a poll(2) for the POLLPRI event.
: This mode is used by rlogin(1) and rlogind(8) to implement a remote-echoed, locally ^S/^Q flow-controlled remote login.


TIOCPKT_FLUSHREAD	The read queue for the terminal is flushed.
TIOCPKT_FLUSHWRITE	The write queue for the terminal is flushed.
TIOCPKT_STOP	Output to the terminal is stopped.
TIOCPKT_START	Output to the terminal is restarted.
TIOCPKT_DOSTOP	The start and stop characters are ^S / ^Q .
TIOCPKT_NOSTOP	The start and stop characters are not ^S / ^Q .

TIOCGPKT: Return the current packet mode setting in the integer pointed to by mode.
TIOCSPTLCK: Set (if *lock is nonzero) or remove (if *lock is zero) the lock on the pseudoterminal slave device. (See also unlockpt(3).)
TIOCGPTLCK: Place the current lock state of the pseudoterminal slave device in the location pointed to by lock.
TIOCGPTPEER: Given a file descriptor in fd that refers to a pseudoterminal master, open (with the given open(2)-style flags) and return a new file descriptor that refers to the peer pseudoterminal slave device. This operation can be performed regardless of whether the pathname of the slave device is accessible through the calling process's mount namespace.

: Security-conscious programs interacting with namespaces may wish to use this operation rather than open(2) with the pathname returned by ptsname(3), and similar library functions that have insecure APIs. (For example, confusion can occur in some cases using ptsname(3) with a pathname where a devpts filesystem has been mounted in a different mount namespace.)

On success, 0 is returned. On error, -1 is returned, and errno is set to indicate the error.

The BSD ioctls TIOCSTOP, TIOCSTART, TIOCUCNTL, and TIOCREMOTE have not been implemented under Linux.