TTY(4) | Device Drivers Manual | TTY(4) |
tty
—
#include <sys/ioctl.h>
The /dev/ttyXX special file is used for dial-in modems and terminals. When a user logs into the system on one of these hardware terminal ports, the system has already opened the associated device and prepared the line for normal interactive use (see getty(8)).
The /dev/dtyXX special file is a SunOS-compatible dial-out device. Unlike the dial-in device, opening the dial-out device never blocks. If the corresponding dial-in device is already opened (not blocked in the open waiting for carrier), then the dial-out open will fail immediately; otherwise it will succeed immediately. While the dial-out device is open, the dial-in device may not be opened. If the dial-in open is blocking, it will wait until the dial-out device is closed (and carrier is detected); otherwise it will fail immediately.
There is also a special case of a terminal file that connects not to a hardware terminal port, but to another program on the other side. These special terminal devices are called ptys (pseudo terminals) and provide the mechanism necessary to give users the same interface to the system when logging in over a network (using rlogin(1), or telnet(1) for example.) Even in these cases the details of how the terminal file was opened and set up is already handled by special software in the system. Thus, users do not normally need to worry about the details of how these lines are opened or used. Also, these lines are often used for dialing out of a system (through an out-calling modem), but again the system provides programs that hide the details of accessing these terminal special files (see tip(1)).
When an interactive user logs in, the system prepares the line to behave in a certain way (called a line discipline), the particular details of which is described in stty(1) at the command level, and in termios(4) at the programming level. A user may be concerned with changing settings associated with his particular login terminal and should refer to the preceding man pages for the common cases. The remainder of this man page is concerned with describing details of using and controlling terminal devices at a low level, such as that possibly required by a program wishing to provide features similar to those provided by the system.
termios
line discipline is associated with
the file. This is the primary line discipline that is used in most cases and
provides the semantics that users normally associate with a terminal. When the
termios
line discipline is in effect, the terminal
file behaves and is operated according to the rules described in
termios(4). Please refer to
that man page for a full description of the terminal semantics. The operations
described here generally represent features common across all
line disciplines, however some of these calls may not make
sense in conjunction with a line discipline other than
termios
, and some may not be supported by the
underlying hardware (or lack thereof, as in the case of ptys).
and would be called on the terminal associated with file descriptor zero by the following code fragment:
ioctl(0, TIOCSLINED, "termios");
TIOCSLINED
char name[32]TIOCGLINED
char name[32]TIOCSBRK
voidTIOCCBRK
voidTIOCSDTR
voidTIOCCDTR
voidTIOCGPGRP
int *tpgrpTIOCSPGRP
int *tpgrpTIOCGETA
struct termios *termTIOCSETA
struct termios *termTCSANOW
option.TIOCSETAW
struct termios *termTCSADRAIN
option.TIOCSETAF
struct termios *termTCSAFLUSH
option.TIOCOUTQ
int *numTIOCSTI
char *cpTIOCNOTTY
voidTIOCNOTTY
on that file descriptor.
The current system does not allocate a controlling terminal to
a process on an open
() call: there is a specific
ioctl called TIOCSCTTY
to make a terminal the
controlling terminal. In addition, a program can
fork
() and call the
setsid
() system call which will place the
process into its own session - which has the effect of disassociating it
from the controlling terminal. This is the new and preferred method for
programs to lose their controlling terminal.
TIOCSTOP
voidTIOCSTART
voidTIOCSCTTY
voidTIOCDRAIN
voidTIOCEXCL
voidTIOCNXCL
voidTIOCFLUSH
int *whatFREAD
bit as defined in
<sys/fcntl.h>
, then all
characters in the input queue are cleared. If it contains the
FWRITE
bit, then all characters in the output
queue are cleared. If the value of the integer is zero, then it behaves as
if both the FREAD
and
FWRITE
bits were set (i.e. clears both
queues).TIOCGWINSZ
struct winsize *ws<sys/ioctl.h>
.TIOCSWINSZ
struct winsize *wsTIOCGQSIZE
int *qsizeTIOCSQSIZE
int *qsize1024
and 65536
and input
values are converted to a power of two. All pending input and output is
dropped.TIOCCONS
int *onTIOCMSET
int *stateThis call sets the terminal modem state to that represented by state. Not all terminals may support this.
TIOCMGET
int *stateTIOCMBIS
int *stateTIOCMBIC
int *stateTIOCSFLAGS
int *stateCLOCAL
flag on open.CRTSCTS
flag on open.MDMBUF
flag on open.This call sets the serial port state to that represented by state. Not all serial ports may support this.
TIOCGFLAGS
int *stateTIOCSETD
int *ldisc<sys/ttycom.h>
and are:
TIOCGETD
int *ldiscSeptember 9, 2011 | NetBSD 9.4 |