termios.h

PROLOG
NAME
SYNOPSIS
DESCRIPTION
APPLICATION USAGE
RATIONALE
FUTURE DIRECTIONS
SEE ALSO
COPYRIGHT

---

PROLOG

This manual page is part of the POSIX Programmer’s Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

termios.h — define values for termios

SYNOPSIS

#include

DESCRIPTION

The 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 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 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 header shall define the following symbolic constant:

NCCS

Size of the array c_cc for control characters.

The header shall define the following symbolic constants for use as subscripts for the array c_cc:

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 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 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 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 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 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 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 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 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 header shall define the pid_t type as described in .

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.

APPLICATION USAGE

The following names are reserved for XSI-conformant systems to use as an extension to the above; therefore strictly conforming applications shall not use them:

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

The System Interfaces volume of POSIX.1-2017, cfgetispeed(), cfgetospeed(), cfsetispeed(), cfsetospeed(), confstr(), tcdrain(), tcflow(), tcflush(), tcgetattr(), tcgetsid(), tcsendbreak(), tcsetattr()

The Shell and Utilities volume of POSIX.1-2017, Chapter 11, General Terminal Interface, getconf

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology — Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

---