cfsetispeed man page on YellowDog

Man page or keyword search:  
man Server   18644 pages
apropos Keyword Search (all sections)
Output format
YellowDog logo
[printable version]

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

NAME
       termios,	 tcgetattr,  tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow,
       cfmakeraw, cfgetospeed, cfgetispeed, cfsetispeed,  cfsetospeed,	cfset‐
       speed - get and set terminal attributes, line control, get and set baud
       rate

SYNOPSIS
       #include <termios.h>
       #include <unistd.h>

       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);

DESCRIPTION
       The  termios  functions	describe  a general terminal interface that is
       provided to control asynchronous communications ports.

       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.

       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	struc‐
	      ture   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 sepa‐
	      rate fields, e.g.	 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 Parity for input and output is odd.

       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.)

       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.  This enables the special characters EOF,
	      EOL,  EOL2, ERASE, KILL, LNEXT, REPRINT, STATUS, and WERASE, and
	      buffers by lines.

       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 char‐
	      acters  are preceded by \ and lowercase characters are converted
	      to uppercase.

       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 imple‐
	      mented 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 the
	      SIGINT, SIGQUIT and SIGSUSP signals.

       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 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 charac‐
	      ter. Send a SIGINT signal.  Recognized when  ISIG	 is  set,  and
	      then not passed as input.

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

       VERASE (0177, DEL, rubout, or 010, BS, Ctrl-H, or also #) Erase charac‐
	      ter. 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.	  Rec‐
	      ognized 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	 wait‐
	      ing  user program without waiting for end-of-line.  If it is the
	      first character of the line, the	read()	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 non-canonical read.

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

       VTIME  Timeout in deciseconds for non-canonical read.

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

       VSWTCH (not in POSIX; not supported under Linux; 0, NUL) Switch charac‐
	      ter. (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 char‐
	      acter typed.  Recognized when IXON is set, and then  not	passed
	      as input.

       VSUSP  (032, SUB, Ctrl-Z) Suspend character. Send SIGTSTP signal.  Rec‐
	      ognized 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 charac‐
	      ter 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) Tog‐
	      gle: start/stop discarding pending output.  Recognized when IEX‐
	      TEN 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 non-
       canonical mode the special character meaning is replaced by the timeout
       meaning.	  MIN  (indexed	 using	VMIN) represents the minimum number of
       characters that should be received to satisfy the read.	TIME  (indexed
       using  VTIME)  is  a decisecond-valued timer. When both are set, a read
       will wait until at least one character  has  been  received,  and  then
       return as soon as either MIN characters have been received or time TIME
       has passed since the last character was received. If only MIN  is  set,
       the  read  will not return before MIN characters have been received. If
       only TIME is set, the read will return as soon as either at  least  one
       character has been received, or the timer times out. If neither is set,
       the read will return immediately, only  giving  the  currently  already
       available characters.

       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 trans‐
	      mitted.	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.

       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.

       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.

       cfmakeraw() sets the terminal attributes 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;

       cfgetospeed() returns the output baud rate stored in the termios struc‐
       ture 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.  Nor‐
       mally, 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 non-zero.

       cfgetispeed() returns the input baud rate stored in the termios	struc‐
       ture.

       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 struc‐
       ture.

       cfgetospeed() returns the output baud rate stored in the termios struc‐
       ture.

       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.

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  non-zero 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 mil‐
       liseconds.  FreeBSD and NetBSD and HP-UX and MacOS ignore the value  of
       duration.   Under  Solaris  and	Unixware,  tcsendbreak() with non-zero
       duration behaves like tcdrain().

SEE ALSO
       stty(1), feature_test_macros(7), setserial(8)

Linux				  2004-10-31			    TERMIOS(3)
[top]

List of man pages available for YellowDog

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net