The <termios.h> header shall contain the definitions used by the
terminal I/O interfaces (see Chapter 11, General Terminal
Interface for the structures and names defined).
The termios Structure
The <termios.h> header shall define the following data types
through typedef:
cc_t Used for terminal special characters.
speed_t Used for terminal baud rates.
tcflag_t Used for terminal modes.
The above types shall be all unsigned integer types.
The implementation shall support one or more programming
environments in which the widths of cc_t, speed_t, and tcflag_t
are no greater than the width of type long. The names of these
programming environments can be obtained using the confstr()
function or the getconf utility.
The <termios.h> header shall define the termios structure, which
shall include at least the following members:
tcflag_t c_iflag Input modes.
tcflag_t c_oflag Output modes.
tcflag_t c_cflag Control modes.
tcflag_t c_lflag Local modes.
cc_t c_cc[NCCS] Control characters.
The <termios.h> header shall define the following symbolic
constant:
NCCS Size of the array c_cc for control characters.
The <termios.h> header shall define the following symbolic
constants for use as subscripts for the array c_cc:
┌────────────────────────────────────┬──────────────────┐
│ Subscript Usage │ │
│Canonical Mode Non-Canonical Mode │ Description │
├───────────────┬────────────────────┼──────────────────┤
│VEOF │ │ EOF character. │
│VEOL │ │ EOL character. │
│VERASE │ │ ERASE character. │
│VINTR │ VINTR │ INTR character. │
│VKILL │ │ KILL character. │
│ │ VMIN │ MIN value. │
│VQUIT │ VQUIT │ QUIT character. │
│VSTART │ VSTART │ START character. │
│VSTOP │ VSTOP │ STOP character. │
│VSUSP │ VSUSP │ SUSP character. │
│ │ VTIME │ TIME value. │
└───────────────┴────────────────────┴──────────────────┘
The subscript values shall be suitable for use in #if
preprocessing directives and shall be distinct, except that the
VMIN and VTIME subscripts may have the same values as the VEOF
and VEOL subscripts, respectively.
Input Modes
The <termios.h> header shall define the following symbolic
constants for use as flags in the c_iflag field. The c_iflag
field describes the basic terminal input control.
BRKINT Signal interrupt on break.
ICRNL Map CR to NL on input.
IGNBRK Ignore break condition.
IGNCR Ignore CR.
IGNPAR Ignore characters with parity errors.
INLCR Map NL to CR on input.
INPCK Enable input parity check.
ISTRIP Strip character.
IXANY Enable any character to restart output.
IXOFF Enable start/stop input control.
IXON Enable start/stop output control.
PARMRK Mark parity errors.
Output Modes
The <termios.h> header shall define the following symbolic
constants for use as flags in the c_oflag field. The c_oflag
field specifies the system treatment of output.
OPOST Post-process output.
ONLCR Map NL to CR-NL on output.
OCRNL Map CR to NL on output.
ONOCR No CR output at column 0.
ONLRET NL performs CR function.
OFDEL Fill is DEL.
OFILL Use fill characters for delay.
NLDLY Select newline delays:
NL0 Newline type 0.
NL1 Newline type 1.
CRDLY Select carriage-return delays:
CR0 Carriage-return delay type 0.
CR1 Carriage-return delay type 1.
CR2 Carriage-return delay type 2.
CR3 Carriage-return delay type 3.
TABDLY Select horizontal-tab delays:
TAB0 Horizontal-tab delay type 0.
TAB1 Horizontal-tab delay type 1.
TAB2 Horizontal-tab delay type 2.
TAB3 Expand tabs to spaces.
BSDLY Select backspace delays:
BS0 Backspace-delay type 0.
BS1 Backspace-delay type 1.
VTDLY Select vertical-tab delays:
VT0 Vertical-tab delay type 0.
VT1 Vertical-tab delay type 1.
FFDLY Select form-feed delays:
FF0 Form-feed delay type 0.
FF1 Form-feed delay type 1.
Baud Rate Selection
The <termios.h> header shall define the following symbolic
constants for use as values of objects of type speed_t.
The input and output baud rates are stored in the termios
structure. These are the valid values for objects of type
speed_t. Not all baud rates need be supported by the underlying
hardware.
B0 Hang up
B50 50 baud
B75 75 baud
B110 110 baud
B134 134.5 baud
B150 150 baud
B200 200 baud
B300 300 baud
B600 600 baud
B1200 1200 baud
B1800 1800 baud
B2400 2400 baud
B4800 4800 baud
B9600 9600 baud
B19200 19200 baud
B38400 38400 baud
Control Modes
The <termios.h> header shall define the following symbolic
constants for use as flags in the c_cflag field. The c_cflag
field describes the hardware control of the terminal; not all
values specified are required to be supported by the underlying
hardware.
CSIZE Character size:
CS5 5 bits
CS6 6 bits
CS7 7 bits
CS8 8 bits
CSTOPB Send two stop bits, else one.
CREAD Enable receiver.
PARENB Parity enable.
PARODD Odd parity, else even.
HUPCL Hang up on last close.
CLOCAL Ignore modem status lines.
The implementation shall support the functionality associated
with the symbols CS7, CS8, CSTOPB, PARODD, and PARENB.
Local Modes
The <termios.h> header shall define the following symbolic
constants for use as flags in the c_lflag field. The c_lflag
field of the argument structure is used to control various
terminal functions.
ECHO Enable echo.
ECHOE Echo erase character as error-correcting backspace.
ECHOK Echo KILL.
ECHONL Echo NL.
ICANON Canonical input (erase and kill processing).
IEXTEN Enable extended input character processing.
ISIG Enable signals.
NOFLSH Disable flush after interrupt or quit.
TOSTOP Send SIGTTOU for background output.
Attribute Selection
The <termios.h> header shall define the following symbolic
constants for use with tcsetattr():
TCSANOW Change attributes immediately.
TCSADRAIN Change attributes when output has drained.
TCSAFLUSH Change attributes when output has drained; also flush
pending input.
Line Control
The <termios.h> header shall define the following symbolic
constants for use with tcflush():
TCIFLUSH Flush pending input.
TCIOFLUSH Flush both pending input and untransmitted output.
TCOFLUSH Flush untransmitted output.
The <termios.h> header shall define the following symbolic
constants for use with tcflow():
TCIOFF Transmit a STOP character, intended to suspend input
data.
TCION Transmit a START character, intended to restart input
data.
TCOOFF Suspend output.
TCOON Restart output.
The <termios.h> header shall define the pid_t type as described
in <sys/types.h>.
The following shall be declared as functions and may also be
defined as macros. Function prototypes shall be provided.
speed_t cfgetispeed(const struct termios *);
speed_t cfgetospeed(const struct termios *);
int cfsetispeed(struct termios *, speed_t);
int cfsetospeed(struct termios *, speed_t);
int tcdrain(int);
int tcflow(int, int);
int tcflush(int, int);
int tcgetattr(int, struct termios *);
pid_t tcgetsid(int);
int tcsendbreak(int, int);
int tcsetattr(int, int, const struct termios *);
The following sections are informative.
