The <termios.h> header contains the definitions used by the
terminal I/O interfaces (see General Terminal Interface for
the structures and names defined).
The termios Structure
The following data types shall be defined 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 structure shall be defined, and 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.
A definition shall be provided for:
NCCS
Size of the array c_cc for control characters.
The following subscript names for the array c_cc shall be defined:
<th colspan="2" align="center"> 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 unique, except that the VMIN and VTIME
subscripts may have the same values as the VEOF and VEOL
subscripts, respectively.
The following flags shall be provided.
Input Modes
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 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.
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 input and output baud rates are stored in the termios structure.
These are the valid values for objects of type
speed_t. The following values shall be defined, but 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 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 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 following symbolic constants for use with tcsetattr() are
defined:
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 following symbolic constants for use with tcflush() shall
be defined:
TCIFLUSH
Flush pending input.
TCIOFLUSH
Flush both pending input and untransmitted output.
TCOFLUSH
Flush untransmitted output.
The following symbolic constants for use with tcflow() shall
be defined:
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 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.
SEE ALSO
The System Interfaces volume of IEEE Std 1003.1-2001, cfgetispeed(),
cfgetospeed(), cfsetispeed(), cfsetospeed(), confstr(),
tcdrain(), tcflow(), tcflush(), tcgetattr(),
tcgetsid(), tcsendbreak(), tcsetattr(), the Shell
and Utilities volume of IEEE Std 1003.1-2001, getconf, General
Terminal Interface
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
