The <termios.h> header shall contain the definitions used by the terminal I/O interfaces (see 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
- [XSI]
![[Option Start]](../images/opt-start.gif)
Map NL to CR-NL on output. ![[Option End]](../images/opt-end.gif)
- OCRNL
- [XSI]
Map CR to NL on output.
- ONOCR
- [XSI]
No CR output at column 0.
- ONLRET
- [XSI]
NL performs CR function.
- OFDEL
- [XSI]
Fill is DEL.
- OFILL
- [XSI]
Use fill characters for delay.
- NLDLY
- [XSI]
Select newline delays:
- NL0
- Newline type 0.
- NL1
- Newline type 1.
- CRDLY
- [XSI]
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
- [XSI]
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
- [XSI]
Select backspace delays:
- BS0
- Backspace-delay type 0.
- BS1
- Backspace-delay type 1.
- VTDLY
- [XSI]
Select vertical-tab delays:
- VT0
- Vertical-tab delay type 0.
- VT1
- Vertical-tab delay type 1.
- FFDLY
- [XSI]
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 *);