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You are here: manpages

termios.h

Section: POSIX Programmer's Manual (0P)
Updated: 2013
Index Return to Main Contents

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 <termios.h>

DESCRIPTION

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.

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:

CBAUD	EXTB	VDSUSP
DEFECHO	FLUSHO	VLNEXT
ECHOCTL	LOBLK	VREPRINT
ECHOKE	PENDIN	VSTATUS
ECHOPRT	SWTCH	VWERASE
EXTA	VDISCARD

RATIONALE

None.

FUTURE DIRECTIONS

None.

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .