termios.h man page

Prolog

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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 ModeNon-Canonical ModeDescription
VEOFEOF character.
VEOLEOL character.
VERASEERASE character.
VINTRVINTRINTR character.
VKILLKILL character.
VMINMIN value.
VQUITVQUITQUIT character.
VSTARTVSTARTSTART character.
VSTOPVSTOPSTOP character.
VSUSPVSUSPSUSP character.
VTIMETIME 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:

CBAUDEXTBVDSUSP
DEFECHOFLUSHOVLNEXT
ECHOCTLLOBLKVREPRINT
ECHOKEPENDINVSTATUS
ECHOPRTSWTCHVWERASE
EXTAVDISCARD

See Also

<sys_types.h>

The System Interfaces volume of POSIX.1‐2008, cfgetispeed(), cfgetospeed(), cfsetispeed(), cfsetospeed(), confstr(), tcdrain(), tcflow(), tcflush(), tcgetattr(), tcgetsid(), tcsendbreak(), tcsetattr()

The Shell and Utilities volume of POSIX.1‐2008, Chapter 11, General Terminal Interface, getconf

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