Linux 串口函数汇总(翻译 man 3 termios)--未做

TERMIOS(3)                    Linux Programmer's Manual                    TERMIOS(3)

NAME

       termios,  tcgetattr,  tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow, cfmak-
       eraw, cfgetospeed, cfgetispeed, cfsetispeed, cfsetospeed, cfsetspeed - get and
       set terminal attributes, line control, get and set baud rate

SYNOPSIS

       #include 
       #include 

       int tcgetattr(int fd, struct termios *termios_p);

       int tcsetattr(int fd, int optional_actions,
                     const struct termios *termios_p);

       int tcsendbreak(int fd, int duration);

       int tcdrain(int fd);

       int tcflush(int fd, int queue_selector);

       int tcflow(int fd, int action);

       void cfmakeraw(struct termios *termios_p);

       speed_t cfgetispeed(const struct termios *termios_p);

       speed_t cfgetospeed(const struct termios *termios_p);

       int cfsetispeed(struct termios *termios_p, speed_t speed);

       int cfsetospeed(struct termios *termios_p, speed_t speed);

       int cfsetspeed(struct termios *termios_p, speed_t speed);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       cfsetspeed(), cfmakeraw(): _BSD_SOURCE

DESCRIPTION

       The termios functions describe a general terminal interface that is provided
       to control asynchronous communications ports.
The termios structure
       Many of the functions described here have a termios_p argument that is a
       pointer to a termios structure.  This structure contains 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 chars */

       The values that may be assigned to these fields are described below.  In the
       case of the first four bit-mask fields, the definitions of some of the
       associated flags that may be set are only exposed if a specific feature test
       macro (see feature_test_macros(7)) is defined, as noted in brackets ("[]").

       In the descriptions below, "not in POSIX" means that the value is not
       specified in POSIX.1-2001, and "XSI" means that the value is specified in
       POSIX.1-2001 as part of the XSI extension.

       c_iflag flag constants:

       IGNBRK Ignore BREAK condition on input.

       BRKINT If IGNBRK is set, a BREAK is ignored.  If it is not set but BRKINT is
              set, then a BREAK causes the input and output queues to be flushed, and
              if the terminal is the controlling terminal of a foreground process
              group, it will cause a SIGINT to be sent to this foreground process
              group.  When neither IGNBRK nor BRKINT are set, a BREAK reads as a null
              byte ('/0'), except when PARMRK is set, in which case it reads as the
              sequence /377 /0 /0.

       IGNPAR Ignore framing errors and parity errors.

       PARMRK If IGNPAR is not set, prefix a character with a parity error or framing
              error with /377 /0.  If neither IGNPAR nor PARMRK is set, read a
              character with a parity error or framing error as /0.

       INPCK  Enable input parity checking.

       ISTRIP Strip off eighth bit.

       INLCR  Translate NL to CR on input.

       IGNCR  Ignore carriage return on input.

       ICRNL  Translate carriage return to newline on input (unless IGNCR is set).

       IUCLC  (not in POSIX) Map uppercase characters to lowercase on input.

       IXON   Enable XON/XOFF flow control on output.

       IXANY  (XSI) Typing any character will restart stopped output.  (The default
              is to allow just the START character to restart output.)

       IXOFF  Enable XON/XOFF flow control on input.

       IMAXBEL
              (not in POSIX) Ring bell when input queue is full.  Linux does not
              implement this bit, and acts as if it is always set.

       IUTF8 (since Linux 2.6.4)
              (not in POSIX) Input is UTF8; this allows character-erase to be
              correctly performed in cooked mode.

       c_oflag flag constants defined in POSIX.1:

       OPOST  Enable implementation-defined output processing.

       The remaining c_oflag flag constants are defined in POSIX.1-2001, unless
       marked otherwise.

       OLCUC  (not in POSIX) Map lowercase characters to uppercase on output.

       ONLCR  (XSI) Map NL to CR-NL on output.

       OCRNL  Map CR to NL on output.

       ONOCR  Don't output CR at column 0.

       ONLRET Don't output CR.

       OFILL  Send fill characters for a delay, rather than using a timed delay.

       OFDEL  (not in POSIX) Fill character is ASCII DEL (0177).  If unset, fill
              character is ASCII NUL ('/0').  (Not implemented on Linux.)

       NLDLY  Newline delay mask.  Values are NL0 and NL1.  [requires _BSD_SOURCE or
              _SVID_SOURCE or _XOPEN_SOURCE]

       CRDLY  Carriage return delay mask.  Values are CR0, CR1, CR2, or CR3.
              [requires _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       TABDLY Horizontal tab delay mask.  Values are TAB0, TAB1, TAB2, TAB3 (or
              XTABS).  A value of TAB3, that is, XTABS, expands tabs to spaces (with
              tab stops every eight columns).  [requires _BSD_SOURCE or _SVID_SOURCE
              or _XOPEN_SOURCE]

       BSDLY  Backspace delay mask.  Values are BS0 or BS1.  (Has never been
              implemented.)  [requires _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       VTDLY  Vertical tab delay mask.  Values are VT0 or VT1.

       FFDLY  Form feed delay mask.  Values are FF0 or FF1.  [requires _BSD_SOURCE or
              _SVID_SOURCE or _XOPEN_SOURCE]

       c_cflag flag constants:

       CBAUD  (not in POSIX) Baud speed mask (4+1 bits).  [requires _BSD_SOURCE or
              _SVID_SOURCE]

       CBAUDEX
              (not in POSIX) Extra baud speed mask (1 bit), included in CBAUD.
              [requires _BSD_SOURCE or _SVID_SOURCE]

              (POSIX says that the baud speed is stored in the termios structure
              without specifying where precisely, and provides cfgetispeed() and
              cfsetispeed() for getting at it.  Some systems use bits selected by
              CBAUD in c_cflag, other systems use separate fields, for example,
              sg_ispeed and sg_ospeed.)

       CSIZE  Character size mask.  Values are CS5, CS6, CS7, or CS8.

       CSTOPB Set two stop bits, rather than one.

       CREAD  Enable receiver.

       PARENB Enable parity generation on output and parity checking for input.

       PARODD If set, then parity for input and output is odd; otherwise even parity
              is used.

       HUPCL  Lower modem control lines after last process closes the device (hang
              up).

       CLOCAL Ignore modem control lines.

       LOBLK  (not in POSIX) Block output from a noncurrent shell layer.  For use by
              shl (shell layers).  (Not implemented on Linux.)

       CIBAUD (not in POSIX) Mask for input speeds.  The values for the CIBAUD bits
              are the same as the values for the CBAUD bits, shifted left IBSHIFT
              bits.  [requires _BSD_SOURCE or _SVID_SOURCE] (Not implemented on
              Linux.)

       CMSPAR (not in POSIX) Use "stick" (mark/space) parity (supported on certain
              serial devices): if PARODD is set, the parity bit is always 1; if
              PARODD is not set, then the parity bit is always 0).  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       CRTSCTS
              (not in POSIX) Enable RTS/CTS (hardware) flow control.  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       c_lflag flag constants:

       ISIG   When any of the characters INTR, QUIT, SUSP, or DSUSP are received,
              generate the corresponding signal.

       ICANON Enable canonical mode (described below).

       XCASE  (not in POSIX; not supported under Linux) If ICANON is also set,
              terminal is uppercase only.  Input is converted to lowercase, except
              for characters preceded by /.  On output, uppercase characters are
              preceded by / and lowercase characters are converted to uppercase.
              [requires _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       ECHO   Echo input characters.

       ECHOE  If ICANON is also set, the ERASE character erases the preceding input
              character, and WERASE erases the preceding word.

       ECHOK  If ICANON is also set, the KILL character erases the current line.

       ECHONL If ICANON is also set, echo the NL character even if ECHO is not set.

       ECHOCTL
              (not in POSIX) If ECHO is also set, ASCII control signals other than
              TAB, NL, START, and STOP are echoed as ^X, where X is the character
              with ASCII code 0x40 greater than the control signal.  For example,
              character 0x08 (BS) is echoed as ^H.  [requires _BSD_SOURCE or
              _SVID_SOURCE]

       ECHOPRT
              (not in POSIX) If ICANON and IECHO are also set, characters are printed
              as they are being erased.  [requires _BSD_SOURCE or _SVID_SOURCE]

       ECHOKE (not in POSIX) If ICANON is also set, KILL is echoed by erasing each
              character on the line, as specified by ECHOE and ECHOPRT.  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       DEFECHO
              (not in POSIX) Echo only when a process is reading.  (Not implemented
              on Linux.)

       FLUSHO (not in POSIX; not supported under Linux) Output is being flushed.
              This flag is toggled by typing the DISCARD character.  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       NOFLSH Disable flushing the input and output queues when generating signals
              for the INT, QUIT, and SUSP characters.

       TOSTOP Send the SIGTTOU signal to the process group of a background process
              which tries to write to its controlling terminal.

       PENDIN (not in POSIX; not supported under Linux) All characters in the input
              queue are reprinted when the next character is read.  (bash(1) handles
              typeahead this way.)  [requires _BSD_SOURCE or _SVID_SOURCE]

       IEXTEN Enable implementation-defined input processing.  This flag, as well as
              ICANON must be enabled for the special characters EOL2, LNEXT, REPRINT,
              WERASE to be interpreted, and for the IUCLC flag to be effective.

       The c_cc array defines the special control characters.  The symbolic indices
       (initial values) and meaning are:

       VINTR  (003, ETX, Ctrl-C, or also 0177, DEL, rubout) Interrupt character.
              Send a SIGINT signal.  Recognized when ISIG is set, and then not passed
              as input.

       VQUIT  (034, FS, Ctrl-/) Quit character.  Send SIGQUIT signal.  Recognized
              when ISIG is set, and then not passed as input.

       VERASE (0177, DEL, rubout, or 010, BS, Ctrl-H, or also #) Erase character.
              This erases the previous not-yet-erased character, but does not erase
              past EOF or beginning-of-line.  Recognized when ICANON is set, and then
              not passed as input.

       VKILL  (025, NAK, Ctrl-U, or Ctrl-X, or also @) Kill character.  This erases
              the input since the last EOF or beginning-of-line.  Recognized when
              ICANON is set, and then not passed as input.

       VEOF   (004, EOT, Ctrl-D) End-of-file character.  More precisely: this
              character causes the pending tty buffer to be sent to the waiting user
              program without waiting for end-of-line.  If it is the first character
              of the line, the read(2) in the user program returns 0, which signifies
              end-of-file.  Recognized when ICANON is set, and then not passed as
              input.

       VMIN   Minimum number of characters for noncanonical read.

       VEOL   (0, NUL) Additional end-of-line character.  Recognized when ICANON is
              set.

       VTIME  Timeout in deciseconds for noncanonical read.

       VEOL2  (not in POSIX; 0, NUL) Yet another end-of-line character.  Recognized
              when ICANON is set.

       VSWTCH (not in POSIX; not supported under Linux; 0, NUL) Switch character.
              (Used by shl only.)

       VSTART (021, DC1, Ctrl-Q) Start character.  Restarts output stopped by the
              Stop character.  Recognized when IXON is set, and then not passed as
              input.

       VSTOP  (023, DC3, Ctrl-S) Stop character.  Stop output until Start character
              typed.  Recognized when IXON is set, and then not passed as input.

       VSUSP  (032, SUB, Ctrl-Z) Suspend character.  Send SIGTSTP signal.  Recognized
              when ISIG is set, and then not passed as input.

       VDSUSP (not in POSIX; not supported under Linux; 031, EM, Ctrl-Y) Delayed
              suspend character: send SIGTSTP signal when the character is read by
              the user program.  Recognized when IEXTEN and ISIG are set, and the
              system supports job control, and then not passed as input.

       VLNEXT (not in POSIX; 026, SYN, Ctrl-V) Literal next.  Quotes the next input
              character, depriving it of a possible special meaning.  Recognized when
              IEXTEN is set, and then not passed as input.

       VWERASE
              (not in POSIX; 027, ETB, Ctrl-W) Word erase.  Recognized when ICANON
              and IEXTEN are set, and then not passed as input.

       VREPRINT
              (not in POSIX; 022, DC2, Ctrl-R) Reprint unread characters.  Recognized
              when ICANON and IEXTEN are set, and then not passed as input.

       VDISCARD
              (not in POSIX; not supported under Linux; 017, SI, Ctrl-O) Toggle:
              start/stop discarding pending output.  Recognized when IEXTEN is set,
              and then not passed as input.

       VSTATUS
              (not in POSIX; not supported under Linux; status request: 024, DC4,
              Ctrl-T).

       These symbolic subscript values are all different, except that VTIME, VMIN may
       have the same value as VEOL, VEOF, respectively.  In noncanonical mode the
       special character meaning is replaced by the timeout meaning.  For an
       explanation of VMIN and VTIME, see the description of noncanonical mode below.
Retrieving and changing terminal settings
       tcgetattr() gets the parameters associated with the object referred by fd and
       stores them in the termios structure referenced by termios_p.  This function
       may be invoked from a background process; however, the terminal attributes may
       be subsequently changed by a foreground process.

       tcsetattr() sets the parameters associated with the terminal (unless support
       is required from the underlying hardware that is not available) from the
       termios structure referred to by termios_p.  optional_actions specifies when
       the changes take effect:

       TCSANOW
              the change occurs immediately.

       TCSADRAIN
              the change occurs after all output written to fd has been transmitted.
              This function should be used when changing parameters that affect
              output.

       TCSAFLUSH
              the change occurs after all output written to the object referred by fd
              has been transmitted, and all input that has been received but not read
              will be discarded before the change is made.
Canonical and noncanonical mode
       The setting of the ICANON canon flag in c_lflag determines whether the
       terminal is operating in canonical mode (ICANON set) or noncanonical mode
       (ICANON unset).  By default, ICANON set.

       In canonical mode:

       * Input is made available line by line.  An input line is available when one
         of the line delimiters is typed (NL, EOL, EOL2; or EOF at the start of
         line).  Except in the case of EOF, the line delimiter is included in the
         buffer returned by read(2).

       * Line editing is enabled (ERASE, KILL; and if the IEXTEN flag is set: WERASE,
         REPRINT, LNEXT).  A read(2) returns at most one line of input; if the
         read(2) requested fewer bytes than are available in the current line of
         input, then only as many bytes as requested are read, and the remaining
         characters will be available for a future read(2).

       In noncanonical mode input is available immediately (without the user having
       to type a line-delimiter character), and line editing is disabled.  The
       settings of MIN (c_cc[VMIN]) and TIME (c_cc[VTIME]) determine the
       circumstances in which a read(2) completes; there are four distinct cases:

       * MIN == 0; TIME == 0: If data is available, read(2) returns immediately, with
         the lesser of the number of bytes available, or the number of bytes
         requested.  If no data is available, read(2) returns 0.

       * MIN > 0; TIME == 0: read(2) blocks until the lesser of MIN bytes or the
         number of bytes requested are available, and returns the lesser of these two
         values.

       * MIN == 0; TIME > 0: TIME specifies the limit for a timer in tenths of a
         second.  The timer is started when read(2) is called.  read(2) returns
         either when at least one byte of data is available, or when the timer
         expires.  If the timer expires without any input becoming available, read(2)
         returns 0.

       * MIN > 0; TIME > 0: TIME specifies the limit for a timer in tenths of a
         second.  Once an initial byte of input becomes available, the timer is
         restarted after each further byte is received.  read(2) returns either when
         the lesser of the number of bytes requested or MIN byte have been read, or
         when the inter-byte timeout expires.  Because the timer is only started
         after the initial byte becomes available, at least one byte will be read.
Raw mode
       cfmakeraw() sets the terminal to something like the "raw" mode of the old
       Version 7 terminal driver: input is available character by character, echoing
       is disabled, and all special processing of terminal input and output
       characters is disabled.  The terminal attributes are set as follows:

           termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);
           termios_p->c_oflag &= ~OPOST;
           termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
           termios_p->c_cflag &= ~(CSIZE | PARENB);
           termios_p->c_cflag |= CS8;
Line control
       tcsendbreak() transmits a continuous stream of zero-valued bits for a specific
       duration, if the terminal is using asynchronous serial data transmission.  If
       duration is zero, it transmits zero-valued bits for at least 0.25 seconds, and
       not more that 0.5 seconds.  If duration is not zero, it sends zero-valued bits
       for some implementation-defined length of time.

       If the terminal is not using asynchronous serial data transmission,
       tcsendbreak() returns without taking any action.

       tcdrain() waits until all output written to the object referred to by fd has
       been transmitted.

       tcflush() discards data written to the object referred to by fd but not
       transmitted, or data received but not read, depending on the value of
       queue_selector:

       TCIFLUSH
              flushes data received but not read.

       TCOFLUSH
              flushes data written but not transmitted.

       TCIOFLUSH
              flushes both data received but not read, and data written but not
              transmitted.

       tcflow() suspends transmission or reception of data on the object referred to
       by fd, depending on the value of action:

       TCOOFF suspends output.

       TCOON  restarts suspended output.

       TCIOFF transmits a STOP character, which stops the terminal device from
              transmitting data to the system.

       TCION  transmits a START character, which starts the terminal device
              transmitting data to the system.

       The default on open of a terminal file is that neither its input nor its
       output is suspended.
Line speed
       The baud rate functions are provided for getting and setting the values of the
       input and output baud rates in the termios structure.  The new values do not
       take effect until tcsetattr() is successfully called.

       Setting the speed to B0 instructs the modem to "hang up".  The actual bit rate
       corresponding to B38400 may be altered with setserial(8).

       The input and output baud rates are stored in the termios structure.

       cfgetospeed() returns the output baud rate stored in the termios structure
       pointed to by termios_p.

       cfsetospeed() sets the output baud rate stored in the termios structure
       pointed to by termios_p to speed, which must be one of these constants:

            B0
            B50
            B75
            B110
            B134
            B150
            B200
            B300
            B600
            B1200
            B1800
            B2400
            B4800
            B9600
            B19200
            B38400
            B57600
            B115200
            B230400

       The zero baud rate, B0, is used to terminate the connection.  If B0 is
       specified, the modem control lines shall no longer be asserted.  Normally,
       this will disconnect the line.  CBAUDEX is a mask for the speeds beyond those
       defined in POSIX.1 (57600 and above).  Thus, B57600 & CBAUDEX is nonzero.

       cfgetispeed() returns the input baud rate stored in the termios structure.

       cfsetispeed() sets the input baud rate stored in the termios structure to
       speed, which must be specified as one of the Bnnn constants listed above for
       cfsetospeed().  If the input baud rate is set to zero, the input baud rate
       will be equal to the output baud rate.

       cfsetspeed() is a 4.4BSD extension.  It takes the same arguments as
       cfsetispeed(), and sets both input and output speed.

RETURN VALUE

       cfgetispeed() returns the input baud rate stored in the termios structure.

       cfgetospeed() returns the output baud rate stored in the termios structure.

       All other functions return:

       0      on success.

       -1     on failure and set errno to indicate the error.

       Note that tcsetattr() returns success if any of the requested changes could be
       successfully carried out.  Therefore, when making multiple changes it may be
       necessary to follow this call with a further call to tcgetattr() to check that
       all changes have been performed successfully.

CONFORMING TO

       tcgetattr(), tcsetattr(), tcsendbreak(), tcdrain(), tcflush(), tcflow(),
       cfgetispeed(), cfgetospeed(), cfsetispeed(), and cfsetospeed() are specified
       in POSIX.1-2001.

       cfmakeraw() and cfsetspeed() are nonstandard, but available on the BSDs.

NOTES

       Unix V7 and several later systems have a list of baud rates where after the
       fourteen values B0, ..., B9600 one finds the two constants EXTA, EXTB
       ("External A" and "External B").  Many systems extend the list with much
       higher baud rates.

       The effect of a nonzero duration with tcsendbreak() varies.  SunOS specifies a
       break of duration * N seconds, where N is at least 0.25, and not more than
       0.5.  Linux, AIX, DU, Tru64 send a break of duration milliseconds.  FreeBSD
       and NetBSD and HP-UX and MacOS ignore the value of duration.  Under Solaris
       and Unixware, tcsendbreak() with nonzero duration behaves like tcdrain().

SEE ALSO

       stty(1), console_ioctl(4), tty_ioctl(4), setserial(8)

COLOPHON

       This page is part of release 3.27 of the Linux man-pages project.  A
       description of the project, and information about reporting bugs, can be found
       at http://www.kernel.org/doc/man-pages/.

Linux                                 2010-06-20                           TERMIOS(3)

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