+++ /dev/null
-.\" Copyright (c) 1993 Michael Haardt
-.\" (michael@moria.de)
-.\" Fri Apr 2 11:32:09 MET DST 1993
-.\"
-.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
-.\" This is free documentation; you can redistribute it and/or
-.\" modify it under the terms of the GNU General Public License as
-.\" published by the Free Software Foundation; either version 2 of
-.\" the License, or (at your option) any later version.
-.\"
-.\" The GNU General Public License's references to "object code"
-.\" and "executables" are to be interpreted as the output of any
-.\" document formatting or typesetting system, including
-.\" intermediate and printed output.
-.\"
-.\" This manual is distributed in the hope that it will be useful,
-.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
-.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-.\" GNU General Public License for more details.
-.\"
-.\" You should have received a copy of the GNU General Public
-.\" License along with this manual; if not, see
-.\" <http://www.gnu.org/licenses/>.
-.\" %%%LICENSE_END
-.\"
-.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
-.\" Modified 1995-02-25 by Jim Van Zandt <jrv@vanzandt.mv.com>
-.\" Modified 1995-09-02 by Jim Van Zandt <jrv@vanzandt.mv.com>
-.\" moved to man3, aeb, 950919
-.\" Modified 2001-09-22 by Michael Kerrisk <mtk.manpages@gmail.com>
-.\" Modified 2001-12-17, aeb
-.\" Modified 2004-10-31, aeb
-.\" 2006-12-28, mtk:
-.\" Added .SS headers to give some structure to this page; and a
-.\" small amount of reordering.
-.\" Added a section on canonical and noncanonical mode.
-.\" Enhanced the discussion of "raw" mode for cfmakeraw().
-.\" Document CMSPAR.
-.\"
-.TH TERMIOS 3 2015-02-01 "Linux" "Linux Programmer's Manual"
-.SH NAME
-termios, tcgetattr, tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow,
-cfmakeraw, cfgetospeed, cfgetispeed, cfsetispeed, cfsetospeed, cfsetspeed \-
-get and set terminal attributes, line control, get and set baud rate
-.SH SYNOPSIS
-.nf
-.B #include <termios.h>
-.br
-.B #include <unistd.h>
-.sp
-.BI "int tcgetattr(int " fd ", struct termios *" termios_p );
-.sp
-.BI "int tcsetattr(int " fd ", int " optional_actions ,
-.BI " const struct termios *" termios_p );
-.sp
-.BI "int tcsendbreak(int " fd ", int " duration );
-.sp
-.BI "int tcdrain(int " fd );
-.sp
-.BI "int tcflush(int " fd ", int " queue_selector );
-.sp
-.BI "int tcflow(int " fd ", int " action );
-.sp
-.BI "void cfmakeraw(struct termios *" termios_p );
-.sp
-.BI "speed_t cfgetispeed(const struct termios *" termios_p );
-.sp
-.BI "speed_t cfgetospeed(const struct termios *" termios_p );
-.sp
-.BI "int cfsetispeed(struct termios *" termios_p ", speed_t " speed );
-.sp
-.BI "int cfsetospeed(struct termios *" termios_p ", speed_t " speed );
-.sp
-.BI "int cfsetspeed(struct termios *" termios_p ", speed_t " speed );
-.fi
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.in
-.sp
-.BR cfsetspeed (),
-.BR cfmakeraw ():
-_BSD_SOURCE
-.SH DESCRIPTION
-The termios functions describe a general terminal interface that is
-provided to control asynchronous communications ports.
-.SS The termios structure
-.LP
-Many of the functions described here have a \fItermios_p\fP argument
-that is a pointer to a \fItermios\fP structure.
-This structure contains at least the following members:
-.sp
-.in +4n
-.nf
-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]; /* special characters */
-.fi
-.in
-.PP
-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
-exposed only if a specific feature test macro (see
-.BR feature_test_macros (7))
-is defined, as noted in brackets ("[]").
-.PP
-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.
-.PP
-\fIc_iflag\fP flag constants:
-.TP
-.B IGNBRK
-Ignore BREAK condition on input.
-.TP
-.B BRKINT
-If \fBIGNBRK\fP is set, a BREAK is ignored.
-If it is not set
-but \fBBRKINT\fP 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
-\fBSIGINT\fP to be sent to this foreground process group.
-When neither \fBIGNBRK\fP nor \fBBRKINT\fP are set, a BREAK
-reads as a null byte (\(aq\\0\(aq), except when \fBPARMRK\fP is set,
-in which case it reads as the sequence \\377 \\0 \\0.
-.TP
-.B IGNPAR
-Ignore framing errors and parity errors.
-.TP
-.B PARMRK
-If \fBIGNPAR\fP is not set, prefix a character with a parity error or
-framing error with \\377 \\0.
-If neither \fBIGNPAR\fP nor \fBPARMRK\fP
-is set, read a character with a parity error or framing error
-as \\0.
-.TP
-.B INPCK
-Enable input parity checking.
-.TP
-.B ISTRIP
-Strip off eighth bit.
-.TP
-.B INLCR
-Translate NL to CR on input.
-.TP
-.B IGNCR
-Ignore carriage return on input.
-.TP
-.B ICRNL
-Translate carriage return to newline on input (unless \fBIGNCR\fP is set).
-.TP
-.B IUCLC
-(not in POSIX) Map uppercase characters to lowercase on input.
-.TP
-.B IXON
-Enable XON/XOFF flow control on output.
-.TP
-.B IXANY
-(XSI) Typing any character will restart stopped output.
-(The default is to allow just the START character to restart output.)
-.TP
-.B IXOFF
-Enable XON/XOFF flow control on input.
-.TP
-.B 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.
-.TP
-.BR IUTF8 " (since Linux 2.6.4)"
-(not in POSIX) Input is UTF8;
-this allows character-erase to be correctly performed in cooked mode.
-.PP
-.I c_oflag
-flag constants:
-.TP
-.B OPOST
-Enable implementation-defined output processing.
-.TP
-.B OLCUC
-(not in POSIX) Map lowercase characters to uppercase on output.
-.TP
-.B ONLCR
-(XSI) Map NL to CR-NL on output.
-.TP
-.B OCRNL
-Map CR to NL on output.
-.TP
-.B ONOCR
-Don't output CR at column 0.
-.TP
-.B ONLRET
-Don't output CR.
-.TP
-.B OFILL
-Send fill characters for a delay, rather than using a timed delay.
-.TP
-.B OFDEL
-Fill character is ASCII DEL (0177).
-If unset, fill character is ASCII NUL (\(aq\\0\(aq).
-(Not implemented on Linux.)
-.TP
-.B NLDLY
-Newline delay mask.
-Values are \fBNL0\fP and \fBNL1\fP.
-[requires
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.TP
-.B CRDLY
-Carriage return delay mask.
-Values are \fBCR0\fP, \fBCR1\fP, \fBCR2\fP, or \fBCR3\fP.
-[requires
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.TP
-.B TABDLY
-Horizontal tab delay mask.
-Values are \fBTAB0\fP, \fBTAB1\fP, \fBTAB2\fP, \fBTAB3\fP (or \fBXTABS\fP).
-A value of TAB3, that is, XTABS, expands tabs to spaces
-(with tab stops every eight columns).
-[requires
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.TP
-.B BSDLY
-Backspace delay mask.
-Values are \fBBS0\fP or \fBBS1\fP.
-(Has never been implemented.)
-[requires
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.TP
-.B VTDLY
-Vertical tab delay mask.
-Values are \fBVT0\fP or \fBVT1\fP.
-.TP
-.B FFDLY
-Form feed delay mask.
-Values are \fBFF0\fP or \fBFF1\fP.
-[requires
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.PP
-\fIc_cflag\fP flag constants:
-.TP
-.B CBAUD
-(not in POSIX) Baud speed mask (4+1 bits).
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B CBAUDEX
-(not in POSIX) Extra baud speed mask (1 bit), included in
-.BR CBAUD .
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.sp
-(POSIX says that the baud speed is stored in the
-.I termios
-structure without specifying where precisely, and provides
-.BR cfgetispeed ()
-and
-.BR cfsetispeed ()
-for getting at it.
-Some systems use bits selected by
-.B CBAUD
-in
-.IR c_cflag ,
-other systems use separate fields, for example,
-.I sg_ispeed
-and
-.IR sg_ospeed .)
-.TP
-.B CSIZE
-Character size mask.
-Values are \fBCS5\fP, \fBCS6\fP, \fBCS7\fP, or \fBCS8\fP.
-.TP
-.B CSTOPB
-Set two stop bits, rather than one.
-.TP
-.B CREAD
-Enable receiver.
-.TP
-.B PARENB
-Enable parity generation on output and parity checking for input.
-.TP
-.B PARODD
-If set, then parity for input and output is odd;
-otherwise even parity is used.
-.TP
-.B HUPCL
-Lower modem control lines after last process closes the device (hang up).
-.TP
-.B CLOCAL
-Ignore modem control lines.
-.TP
-.B LOBLK
-(not in POSIX) Block output from a noncurrent shell layer.
-For use by \fBshl\fP (shell layers). (Not implemented on Linux.)
-.TP
-.B CIBAUD
-(not in POSIX) Mask for input speeds.
-The values for the
-.B CIBAUD
-bits are
-the same as the values for the
-.B CBAUD
-bits, shifted left
-.B IBSHIFT
-bits.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-(Not implemented on Linux.)
-.TP
-.B CMSPAR
-(not in POSIX)
-Use "stick" (mark/space) parity (supported on certain serial
-devices): if
-.B PARODD
-is set, the parity bit is always 1; if
-.B PARODD
-is not set, then the parity bit is always 0.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B CRTSCTS
-(not in POSIX) Enable RTS/CTS (hardware) flow control.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.PP
-\fIc_lflag\fP flag constants:
-.TP
-.B ISIG
-When any of the characters INTR, QUIT, SUSP, or DSUSP are received,
-generate the corresponding signal.
-.TP
-.B ICANON
-Enable canonical mode (described below).
-.TP
-.B XCASE
-(not in POSIX; not supported under Linux)
-If \fBICANON\fP 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
-.B _BSD_SOURCE
-or
-.B _SVID_SOURCE
-or
-.BR _XOPEN_SOURCE ]
-.\" glibc is probably now wrong to allow
-.\" Define
-.\" .B _XOPEN_SOURCE
-.\" to expose
-.\" .BR XCASE .
-.TP
-.B ECHO
-Echo input characters.
-.TP
-.B ECHOE
-If \fBICANON\fP is also set, the ERASE character erases the preceding
-input character, and WERASE erases the preceding word.
-.TP
-.B ECHOK
-If \fBICANON\fP is also set, the KILL character erases the current line.
-.TP
-.B ECHONL
-If \fBICANON\fP is also set, echo the NL character even if ECHO is not set.
-.TP
-.B ECHOCTL
-(not in POSIX) If \fBECHO\fP is also set,
-terminal special characters other than
-TAB, NL, START, and STOP are echoed as \fB^X\fP,
-where X is the character with
-ASCII code 0x40 greater than the special character.
-For example, character
-0x08 (BS) is echoed as \fB^H\fP.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B ECHOPRT
-(not in POSIX) If \fBICANON\fP and \fBECHO\fP are also set, characters
-are printed as they are being erased.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B ECHOKE
-(not in POSIX) If \fBICANON\fP is also set, KILL is echoed by erasing
-each character on the line, as specified by \fBECHOE\fP and \fBECHOPRT\fP.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B DEFECHO
-(not in POSIX) Echo only when a process is reading.
-(Not implemented on Linux.)
-.TP
-.B FLUSHO
-(not in POSIX; not supported under Linux)
-Output is being flushed.
-This flag is toggled by typing
-the DISCARD character.
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B NOFLSH
-Disable flushing the input and output queues when generating signals for the
-INT, QUIT, and SUSP characters.
-.\" Stevens lets SUSP only flush the input queue
-.TP
-.B TOSTOP
-Send the
-.B SIGTTOU
-signal to the process group of a background process
-which tries to write to its controlling terminal.
-.TP
-.B PENDIN
-(not in POSIX; not supported under Linux)
-All characters in the input queue are reprinted when
-the next character is read.
-.RB ( bash (1)
-handles typeahead this way.)
-[requires
-.B _BSD_SOURCE
-or
-.BR _SVID_SOURCE ]
-.TP
-.B IEXTEN
-Enable implementation-defined input processing.
-This flag, as well as \fBICANON\fP must be enabled for the
-special characters EOL2, LNEXT, REPRINT, WERASE to be interpreted,
-and for the \fBIUCLC\fP flag to be effective.
-.PP
-The \fIc_cc\fP array defines the terminal special characters.
-The symbolic indices (initial values) and meaning are:
-.TP
-.B VDISCARD
-(not in POSIX; not supported under Linux; 017, SI, Ctrl-O)
-Toggle: start/stop discarding pending output.
-Recognized when
-.B IEXTEN
-is set, and then not passed as input.
-.TP
-.B VDSUSP
-(not in POSIX; not supported under Linux; 031, EM, Ctrl-Y)
-Delayed suspend character (DSUSP):
-send
-.B SIGTSTP
-signal when the character is read by the user program.
-Recognized when
-.B IEXTEN
-and
-.B ISIG
-are set, and the system supports
-job control, and then not passed as input.
-.TP
-.B VEOF
-(004, EOT, Ctrl-D)
-End-of-file character (EOF).
-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
-.BR read (2)
-in the user program returns 0, which signifies end-of-file.
-Recognized when
-.B ICANON
-is set, and then not passed as input.
-.TP
-.B VEOL
-(0, NUL)
-Additional end-of-line character (EOL).
-Recognized when
-.B ICANON
-is set.
-.TP
-.B VEOL2
-(not in POSIX; 0, NUL)
-Yet another end-of-line character (EOL2).
-Recognized when
-.B ICANON
-is set.
-.TP
-.B VERASE
-(0177, DEL, rubout, or 010, BS, Ctrl-H, or also #)
-Erase character (ERASE).
-This erases the previous not-yet-erased character,
-but does not erase past EOF or beginning-of-line.
-Recognized when
-.B ICANON
-is set, and then not passed as input.
-.TP
-.B VINTR
-(003, ETX, Ctrl-C, or also 0177, DEL, rubout)
-Interrupt character (INTR).
-Send a
-.B SIGINT
-signal.
-Recognized when
-.B ISIG
-is set, and then not passed as input.
-.TP
-.B VKILL
-(025, NAK, Ctrl-U, or Ctrl-X, or also @)
-Kill character (KILL).
-This erases the input since the last EOF or beginning-of-line.
-Recognized when
-.B ICANON
-is set, and then not passed as input.
-.TP
-.B VLNEXT
-(not in POSIX; 026, SYN, Ctrl-V)
-Literal next (LNEXT).
-Quotes the next input character, depriving it of
-a possible special meaning.
-Recognized when
-.B IEXTEN
-is set, and then not passed as input.
-.TP
-.B VMIN
-Minimum number of characters for noncanonical read (MIN).
-.TP
-.B VQUIT
-(034, FS, Ctrl-\e)
-Quit character (QUIT).
-Send
-.B SIGQUIT
-signal.
-Recognized when
-.B ISIG
-is set, and then not passed as input.
-.TP
-.B VREPRINT
-(not in POSIX; 022, DC2, Ctrl-R)
-Reprint unread characters (REPRINT).
-Recognized when
-.B ICANON
-and
-.B IEXTEN
-are set, and then not passed as input.
-.TP
-.B VSTART
-(021, DC1, Ctrl-Q)
-Start character (START).
-Restarts output stopped by the Stop character.
-Recognized when
-.B IXON
-is set, and then not passed as input.
-.TP
-.B VSTATUS
-(not in POSIX; not supported under Linux;
-status request: 024, DC4, Ctrl-T).
-Status character (STATUS).
-Display status information at terminal,
-including state of foreground process and amount of CPU time it has consumed.
-Also sends a
-.BR SIGINFO
-signal (not supported on Linux) to the foreground process group.
-.TP
-.B VSTOP
-(023, DC3, Ctrl-S)
-Stop character (STOP).
-Stop output until Start character typed.
-Recognized when
-.B IXON
-is set, and then not passed as input.
-.TP
-.B VSUSP
-(032, SUB, Ctrl-Z)
-Suspend character (SUSP).
-Send
-.B SIGTSTP
-signal.
-Recognized when
-.B ISIG
-is set, and then not passed as input.
-.TP
-.B VSWTCH
-(not in POSIX; not supported under Linux; 0, NUL)
-Switch character (SWTCH).
-Used in System V to switch shells in
-.IR "shell layers" ,
-a predecessor to shell job control.
-.TP
-.B VTIME
-Timeout in deciseconds for noncanonical read (TIME).
-.TP
-.B VWERASE
-(not in POSIX; 027, ETB, Ctrl-W)
-Word erase (WERASE).
-Recognized when
-.B ICANON
-and
-.B IEXTEN
-are set, and then not passed as input.
-.LP
-An individual terminal special character can be disabled by setting
-the value of the corresponding
-.I c_cc
-element to
-.BR _POSIX_VDISABLE .
-.LP
-The above symbolic subscript values are all different, except that
-.BR VTIME ,
-.B VMIN
-may have the same value as
-.BR VEOL ,
-.BR VEOF ,
-respectively.
-In noncanonical mode the special character meaning is replaced
-by the timeout meaning.
-For an explanation of
-.B VMIN
-and
-.BR VTIME ,
-see the description of
-noncanonical mode below.
-.SS Retrieving and changing terminal settings
-.PP
-.BR tcgetattr ()
-gets the parameters associated with the object referred by \fIfd\fP and
-stores them in the \fItermios\fP structure referenced by
-\fItermios_p\fP.
-This function may be invoked from a background process;
-however, the terminal attributes may be subsequently changed by a
-foreground process.
-.LP
-.BR tcsetattr ()
-sets the parameters associated with the terminal (unless support is
-required from the underlying hardware that is not available) from the
-\fItermios\fP structure referred to by \fItermios_p\fP.
-\fIoptional_actions\fP specifies when the changes take effect:
-.IP \fBTCSANOW\fP
-the change occurs immediately.
-.IP \fBTCSADRAIN\fP
-the change occurs after all output written to
-.I fd
-has been transmitted.
-This option should be used when changing
-parameters that affect output.
-.IP \fBTCSAFLUSH\fP
-the change occurs after all output written to the object referred by
-.I fd
-has been transmitted, and all input that has been received but not read
-will be discarded before the change is made.
-.SS Canonical and noncanonical mode
-The setting of the
-.B ICANON
-canon flag in
-.I c_lflag
-determines whether the terminal is operating in canonical mode
-.RB ( ICANON
-set) or
-noncanonical mode
-.RB ( ICANON
-unset).
-By default,
-.B ICANON
-set.
-
-In canonical mode:
-.IP * 2
-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
-.BR read (2).
-.IP * 2
-Line editing is enabled (ERASE, KILL;
-and if the
-.B IEXTEN
-flag is set: WERASE, REPRINT, LNEXT).
-A
-.BR read (2)
-returns at most one line of input; if the
-.BR 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
-.BR read (2).
-.PP
-In noncanonical mode input is available immediately (without
-the user having to type a line-delimiter character),
-no input processing is performed,
-and line editing is disabled.
-The settings of MIN
-.RI ( c_cc[VMIN] )
-and TIME
-.RI ( c_cc[VTIME] )
-determine the circumstances in which a
-.BR read (2)
-completes; there are four distinct cases:
-.TP
-MIN == 0, TIME == 0 (polling read)
-If data is available,
-.BR read (2)
-returns immediately, with the lesser of the number of bytes
-available, or the number of bytes requested.
-If no data is available,
-.BR read (2)
-returns 0.
-.TP
-MIN > 0, TIME == 0 (blocking read)
-.BR read (2)
-blocks until MIN bytes are available,
-and returns up to the number of bytes requested.
-.TP
-MIN == 0, TIME > 0 (read with timeout)
-TIME specifies the limit for a timer in tenths of a second.
-The timer is started when
-.BR read (2)
-is called.
-.BR 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,
-.BR read (2)
-returns 0.
-If data is already available at the time of the call to
-.BR read (2),
-the call behaves as though the data was received immediately after the call.
-.TP
-MIN > 0, TIME > 0 (read with interbyte timeout)
-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.
-.BR read (2)
-returns when any of the following conditions is met:
-.RS
-.IP * 3
-MIN bytes have been received.
-.IP *
-The interbyte timer expires.
-.IP *
-The number of bytes requested by
-.BR read (2)
-has been received.
-(POSIX does not specify this termination condition,
-and on some other implementations
-.\" e.g., Solaris
-.BR read (2)
-does not return in this case.)
-.RE
-.IP
-Because the timer is started only after the initial byte
-becomes available, at least one byte will be read.
-If data is already available at the time of the call to
-.BR read (2),
-the call behaves as though the data was received immediately after the call.
-.PP
-POSIX
-.\" POSIX.1-2008 XBD 11.1.7
-does not specify whether the setting of the
-.B O_NONBLOCK
-file status flag takes precedence over the MIN and TIME settings.
-If
-.B O_NONBLOCK
-is set, a
-.BR read (2)
-in noncanonical mode may return immediately,
-regardless of the setting of MIN or TIME.
-Furthermore, if no data is available,
-POSIX permits a
-.BR read (2)
-in noncanonical mode to return either 0, or \-1 with
-.I errno
-set to
-.BR EAGAIN .
-.SS Raw mode
-.LP
-.BR 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:
-.nf
-
- 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;
-.fi
-.SS Line control
-.LP
-.BR tcsendbreak ()
-transmits a continuous stream of zero-valued bits for a specific
-duration, if the terminal is using asynchronous serial data
-transmission.
-If \fIduration\fP is zero, it transmits zero-valued bits
-for at least 0.25 seconds, and not more that 0.5 seconds.
-If \fIduration\fP is not zero, it sends zero-valued bits for some
-implementation-defined length of time.
-.LP
-If the terminal is not using asynchronous serial data transmission,
-.BR tcsendbreak ()
-returns without taking any action.
-.LP
-.BR tcdrain ()
-waits until all output written to the object referred to by
-.I fd
-has been transmitted.
-.LP
-.BR tcflush ()
-discards data written to the object referred to by
-.I fd
-but not transmitted, or data received but not read, depending on the
-value of
-.IR queue_selector :
-.IP \fBTCIFLUSH\fP
-flushes data received but not read.
-.IP \fBTCOFLUSH\fP
-flushes data written but not transmitted.
-.IP \fBTCIOFLUSH\fP
-flushes both data received but not read, and data written but not
-transmitted.
-.LP
-.BR tcflow ()
-suspends transmission or reception of data on the object referred to by
-.IR fd ,
-depending on the value of
-.IR action :
-.IP \fBTCOOFF\fP
-suspends output.
-.IP \fBTCOON\fP
-restarts suspended output.
-.IP \fBTCIOFF\fP
-transmits a STOP character, which stops the terminal device from
-transmitting data to the system.
-.IP \fBTCION\fP
-transmits a START character, which starts the terminal device
-transmitting data to the system.
-.LP
-The default on open of a terminal file is that neither its input nor its
-output is suspended.
-.SS Line speed
-The baud rate functions are provided for getting and setting the values
-of the input and output baud rates in the \fItermios\fP structure.
-The new values do not take effect
-until
-.BR tcsetattr ()
-is successfully called.
-
-Setting the speed to \fBB0\fP instructs the modem to "hang up".
-The actual bit rate corresponding to \fBB38400\fP may be altered with
-.BR setserial (8).
-.LP
-The input and output baud rates are stored in the \fItermios\fP
-structure.
-.LP
-.BR cfgetospeed ()
-returns the output baud rate stored in the \fItermios\fP structure
-pointed to by
-.IR termios_p .
-.LP
-.BR cfsetospeed ()
-sets the output baud rate stored in the \fItermios\fP structure pointed
-to by \fItermios_p\fP to \fIspeed\fP, which must be one of these constants:
-.nf
-
-.ft B
- B0
- B50
- B75
- B110
- B134
- B150
- B200
- B300
- B600
- B1200
- B1800
- B2400
- B4800
- B9600
- B19200
- B38400
- B57600
- B115200
- B230400
-.ft P
-
-.fi
-The zero baud rate, \fBB0\fP,
-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.
-\fBCBAUDEX\fP is a mask
-for the speeds beyond those defined in POSIX.1 (57600 and above).
-Thus, \fBB57600\fP & \fBCBAUDEX\fP is nonzero.
-.LP
-.BR cfgetispeed ()
-returns the input baud rate stored in the \fItermios\fP structure.
-.LP
-.BR cfsetispeed ()
-sets the input baud rate stored in the \fItermios\fP structure to
-.IR speed ,
-which must be specified as one of the \fBBnnn\fP constants listed above for
-.BR cfsetospeed ().
-If the input baud rate is set to zero, the input baud rate will be
-equal to the output baud rate.
-.LP
-.BR cfsetspeed ()
-is a 4.4BSD extension.
-It takes the same arguments as
-.BR cfsetispeed (),
-and sets both input and output speed.
-.SH RETURN VALUE
-.LP
-.BR cfgetispeed ()
-returns the input baud rate stored in the
-\fItermios\fP
-structure.
-.LP
-.BR cfgetospeed ()
-returns the output baud rate stored in the \fItermios\fP structure.
-.LP
-All other functions return:
-.IP 0
-on success.
-.IP \-1
-on failure and set
-.I errno
-to indicate the error.
-.LP
-Note that
-.BR tcsetattr ()
-returns success if \fIany\fP 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
-.BR tcgetattr ()
-to check that all changes have been performed successfully.
-.SH ATTRIBUTES
-.SS Multithreading (see pthreads(7))
-The
-.BR tcgetattr (),
-.BR tcsetattr (),
-.BR tcsendbreak (),
-.BR tcdrain (),
-.BR tcflush (),
-.BR tcflow (),
-.BR cfmakeraw (),
-.BR cfgetispeed (),
-.BR cfgetospeed (),
-.BR cfsetispeed (),
-.BR cfsetospeed (),
-and
-.BR cfsetspeed ()
-functions are thread-safe.
-.SH CONFORMING TO
-.BR tcgetattr (),
-.BR tcsetattr (),
-.BR tcsendbreak (),
-.BR tcdrain (),
-.BR tcflush (),
-.BR tcflow (),
-.BR cfgetispeed (),
-.BR cfgetospeed (),
-.BR cfsetispeed (),
-and
-.BR cfsetospeed ()
-are specified in POSIX.1-2001.
-
-.BR cfmakeraw ()
-and
-.BR cfsetspeed ()
-are nonstandard, but available on the BSDs.
-.SH 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.
-.LP
-The effect of a nonzero \fIduration\fP with
-.BR tcsendbreak ()
-varies.
-SunOS specifies a break of
-.I "duration\ *\ N"
-seconds, where \fIN\fP is at least 0.25, and not more than 0.5.
-Linux, AIX, DU, Tru64 send a break of
-.I duration
-milliseconds.
-FreeBSD and NetBSD and HP-UX and MacOS ignore the value of
-.IR duration .
-Under Solaris and UnixWare,
-.BR tcsendbreak ()
-with nonzero
-.I duration
-behaves like
-.BR tcdrain ().
-.\" libc4 until 4.7.5, glibc for sysv: EINVAL for duration > 0.
-.\" libc4.7.6, libc5, glibc for unix: duration in ms.
-.\" glibc for bsd: duration in us
-.\" glibc for sunos4: ignore duration
-.SH SEE ALSO
-.BR reset (1),
-.BR setterm (1),
-.BR stty (1),
-.BR tput (1),
-.BR tset (1),
-.BR console_ioctl (4),
-.BR tty_ioctl (4),
-.BR setserial (8)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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