mirror of https://github.com/mkerrisk/man-pages
1166 lines
29 KiB
Groff
1166 lines
29 KiB
Groff
.\" Copyright (c) 1993 Michael Haardt (michael@moria.de)
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.\" Fri Apr 2 11:32:09 MET DST 1993
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.\" Copyright (c) 2006-2015, Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, see
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.\" <http://www.gnu.org/licenses/>.
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.\" %%%LICENSE_END
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.\"
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.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
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.\" Modified 1995-02-25 by Jim Van Zandt <jrv@vanzandt.mv.com>
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.\" Modified 1995-09-02 by Jim Van Zandt <jrv@vanzandt.mv.com>
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.\" moved to man3, aeb, 950919
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.\" Modified 2001-09-22 by Michael Kerrisk <mtk.manpages@gmail.com>
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.\" Modified 2001-12-17, aeb
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.\" Modified 2004-10-31, aeb
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.\" 2006-12-28, mtk:
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.\" Added .SS headers to give some structure to this page; and a
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.\" small amount of reordering.
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.\" Added a section on canonical and noncanonical mode.
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.\" Enhanced the discussion of "raw" mode for cfmakeraw().
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.\" Document CMSPAR.
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.\"
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.TH TERMIOS 3 2021-08-27 "Linux" "Linux Programmer's Manual"
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.SH NAME
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termios, tcgetattr, tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow,
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cfmakeraw, cfgetospeed, cfgetispeed, cfsetispeed, cfsetospeed, cfsetspeed \-
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get and set terminal attributes, line control, get and set baud rate
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.SH SYNOPSIS
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.nf
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|
.B #include <termios.h>
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.B #include <unistd.h>
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.PP
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|
.BI "int tcgetattr(int " fd ", struct termios *" termios_p );
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|
.BI "int tcsetattr(int " fd ", int " optional_actions ,
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|
.BI " const struct termios *" termios_p );
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|
.PP
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|
.BI "int tcsendbreak(int " fd ", int " duration );
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|
.BI "int tcdrain(int " fd );
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|
.BI "int tcflush(int " fd ", int " queue_selector );
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.BI "int tcflow(int " fd ", int " action );
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.PP
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|
.BI "void cfmakeraw(struct termios *" termios_p );
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.PP
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|
.BI "speed_t cfgetispeed(const struct termios *" termios_p );
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.BI "speed_t cfgetospeed(const struct termios *" termios_p );
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.PP
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|
.BI "int cfsetispeed(struct termios *" termios_p ", speed_t " speed );
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.BI "int cfsetospeed(struct termios *" termios_p ", speed_t " speed );
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.BI "int cfsetspeed(struct termios *" termios_p ", speed_t " speed );
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.fi
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|
.PP
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|
.RS -4
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|
Feature Test Macro Requirements for glibc (see
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|
.BR feature_test_macros (7)):
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|
.RE
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|
.PP
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|
.BR cfsetspeed (),
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|
.BR cfmakeraw ():
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|
.nf
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|
Since glibc 2.19:
|
|
_DEFAULT_SOURCE
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|
Glibc 2.19 and earlier:
|
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_BSD_SOURCE
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|
.fi
|
|
.SH DESCRIPTION
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|
The termios functions describe a general terminal interface that is
|
|
provided to control asynchronous communications ports.
|
|
.SS The termios structure
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|
Many of the functions described here have a \fItermios_p\fP argument
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|
that is a pointer to a \fItermios\fP structure.
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|
This structure contains at least the following members:
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|
.PP
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|
.in +4n
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|
.EX
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|
tcflag_t c_iflag; /* input modes */
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tcflag_t c_oflag; /* output modes */
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|
tcflag_t c_cflag; /* control modes */
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|
tcflag_t c_lflag; /* local modes */
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cc_t c_cc[NCCS]; /* special characters */
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|
.EE
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|
.in
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|
.PP
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|
The values that may be assigned to these fields are described below.
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|
In the case of the first four bit-mask fields,
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|
the definitions of some of the associated flags that may be set are
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|
exposed only if a specific feature test macro (see
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|
.BR feature_test_macros (7))
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|
is defined, as noted in brackets ("[]").
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|
.PP
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|
In the descriptions below, "not in POSIX" means that the
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|
value is not specified in POSIX.1-2001,
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|
and "XSI" means that the value is specified in POSIX.1-2001
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|
as part of the XSI extension.
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|
.PP
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|
\fIc_iflag\fP flag constants:
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|
.TP
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|
.B IGNBRK
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|
Ignore BREAK condition on input.
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.TP
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|
.B BRKINT
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|
If \fBIGNBRK\fP is set, a BREAK is ignored.
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|
If it is not set
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|
but \fBBRKINT\fP is set, then a BREAK causes the input and output
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|
queues to be flushed, and if the terminal is the controlling
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|
terminal of a foreground process group, it will cause a
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|
\fBSIGINT\fP to be sent to this foreground process group.
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|
When neither \fBIGNBRK\fP nor \fBBRKINT\fP are set, a BREAK
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|
reads as a null byte (\(aq\e0\(aq), except when \fBPARMRK\fP is set,
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|
in which case it reads as the sequence \e377 \e0 \e0.
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.TP
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|
.B IGNPAR
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|
Ignore framing errors and parity errors.
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.TP
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|
.B PARMRK
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|
If this bit is set, input bytes with parity or framing errors are
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|
marked when passed to the program.
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|
This bit is meaningful only when
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|
\fBINPCK\fP is set and \fBIGNPAR\fP is not set.
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|
The way erroneous bytes are marked is with two preceding bytes,
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|
\e377 and \e0.
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|
Thus, the program actually reads three bytes for one
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|
erroneous byte received from the terminal.
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|
If a valid byte has the value \e377,
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and \fBISTRIP\fP (see below) is not set,
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|
the program might confuse it with the prefix that marks a
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parity error.
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|
Therefore, a valid byte \e377 is passed to the program as two
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|
bytes, \e377 \e377, in this case.
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|
.IP
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|
If neither \fBIGNPAR\fP nor \fBPARMRK\fP
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is set, read a character with a parity error or framing error
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|
as \e0.
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.TP
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|
.B INPCK
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|
Enable input parity checking.
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|
.TP
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|
.B ISTRIP
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|
Strip off eighth bit.
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.TP
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.B INLCR
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|
Translate NL to CR on input.
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.TP
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|
.B IGNCR
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|
Ignore carriage return on input.
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|
.TP
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|
.B ICRNL
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|
Translate carriage return to newline on input (unless \fBIGNCR\fP is set).
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|
.TP
|
|
.B IUCLC
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|
(not in POSIX) Map uppercase characters to lowercase on input.
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.TP
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.B IXON
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|
Enable XON/XOFF flow control on output.
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|
.TP
|
|
.B IXANY
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|
(XSI) Typing any character will restart stopped output.
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(The default is to allow just the START character to restart output.)
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.TP
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|
.B IXOFF
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|
Enable XON/XOFF flow control on input.
|
|
.TP
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|
.B IMAXBEL
|
|
(not in POSIX) Ring bell when input queue is full.
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|
Linux does not implement this bit, and acts as if it is always set.
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|
.TP
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|
.BR IUTF8 " (since Linux 2.6.4)"
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|
(not in POSIX) Input is UTF8;
|
|
this allows character-erase to be correctly performed in cooked mode.
|
|
.PP
|
|
.I c_oflag
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|
flag constants:
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|
.TP
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|
.B OPOST
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|
Enable implementation-defined output processing.
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.TP
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|
.B OLCUC
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|
(not in POSIX) Map lowercase characters to uppercase on output.
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.TP
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|
.B ONLCR
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|
(XSI) Map NL to CR-NL on output.
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.TP
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|
.B OCRNL
|
|
Map CR to NL on output.
|
|
.TP
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|
.B ONOCR
|
|
Don't output CR at column 0.
|
|
.TP
|
|
.B ONLRET
|
|
Don't output CR.
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|
.TP
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|
.B OFILL
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|
Send fill characters for a delay, rather than using a timed delay.
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|
.TP
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|
.B OFDEL
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|
Fill character is ASCII DEL (0177).
|
|
If unset, fill character is ASCII NUL (\(aq\e0\(aq).
|
|
(Not implemented on Linux.)
|
|
.TP
|
|
.B NLDLY
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|
Newline delay mask.
|
|
Values are \fBNL0\fP and \fBNL1\fP.
|
|
[requires
|
|
.B _BSD_SOURCE
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|
or
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|
.B _SVID_SOURCE
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|
or
|
|
.BR _XOPEN_SOURCE ]
|
|
.TP
|
|
.B CRDLY
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|
Carriage return delay mask.
|
|
Values are \fBCR0\fP, \fBCR1\fP, \fBCR2\fP, or \fBCR3\fP.
|
|
[requires
|
|
.B _BSD_SOURCE
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|
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,
|
|
but see the
|
|
.B BUGS
|
|
section).
|
|
A value of TAB3, that is, XTABS, expands tabs to spaces
|
|
(with tab stops every eight columns).
|
|
[requires
|
|
.B _BSD_SOURCE
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|
or
|
|
.B _SVID_SOURCE
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|
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
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|
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
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|
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 ]
|
|
.IP
|
|
(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 \e.
|
|
On output, uppercase characters are preceded by \e 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\(haX\fP,
|
|
where X is the character with
|
|
ASCII code 0x40 greater than the special character.
|
|
For example, character
|
|
0x08 (BS) is echoed as \fB\(haH\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
|
|
.B 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.
|
|
.PP
|
|
An individual terminal special character can be disabled by setting
|
|
the value of the corresponding
|
|
.I c_cc
|
|
element to
|
|
.BR _POSIX_VDISABLE .
|
|
.PP
|
|
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
|
|
.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.
|
|
.PP
|
|
.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
|
|
is set.
|
|
.PP
|
|
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).
|
|
.IP * 2
|
|
The maximum line length is 4096 chars
|
|
(including the terminating newline character);
|
|
lines longer than 4096 chars are truncated.
|
|
After 4095 characters, input processing (e.g.,
|
|
.B ISIG
|
|
and
|
|
.B ECHO*
|
|
processing) continues, but any input data after 4095 characters up to
|
|
(but not including) any terminating newline is discarded.
|
|
This ensures that the terminal can always receive
|
|
more input until at least one line can be read.
|
|
.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 read buffer will only accept 4095 chars; this provides the
|
|
necessary space for a newline char if the input mode is switched
|
|
to canonical.
|
|
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
|
|
.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:
|
|
.PP
|
|
.in +4n
|
|
.EX
|
|
termios_p\->c_iflag &= \(ti(IGNBRK | BRKINT | PARMRK | ISTRIP
|
|
| INLCR | IGNCR | ICRNL | IXON);
|
|
termios_p\->c_oflag &= \(tiOPOST;
|
|
termios_p\->c_lflag &= \(ti(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
|
|
termios_p\->c_cflag &= \(ti(CSIZE | PARENB);
|
|
termios_p\->c_cflag |= CS8;
|
|
.EE
|
|
.in
|
|
.\"
|
|
.SS Line control
|
|
.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 than 0.5 seconds.
|
|
If \fIduration\fP is not zero, it sends zero-valued bits for some
|
|
implementation-defined length of time.
|
|
.PP
|
|
If the terminal is not using asynchronous serial data transmission,
|
|
.BR tcsendbreak ()
|
|
returns without taking any action.
|
|
.PP
|
|
.BR tcdrain ()
|
|
waits until all output written to the object referred to by
|
|
.I fd
|
|
has been transmitted.
|
|
.PP
|
|
.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.
|
|
.PP
|
|
.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.
|
|
.PP
|
|
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.
|
|
.PP
|
|
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).
|
|
.PP
|
|
The input and output baud rates are stored in the \fItermios\fP
|
|
structure.
|
|
.PP
|
|
.BR cfgetospeed ()
|
|
returns the output baud rate stored in the \fItermios\fP structure
|
|
pointed to by
|
|
.IR termios_p .
|
|
.PP
|
|
.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:
|
|
.PP
|
|
.nf
|
|
.ft B
|
|
B0
|
|
B50
|
|
B75
|
|
B110
|
|
B134
|
|
B150
|
|
B200
|
|
B300
|
|
B600
|
|
B1200
|
|
B1800
|
|
B2400
|
|
B4800
|
|
B9600
|
|
B19200
|
|
B38400
|
|
B57600
|
|
B115200
|
|
B230400
|
|
B460800
|
|
B500000
|
|
B576000
|
|
B921600
|
|
B1000000
|
|
B1152000
|
|
B1500000
|
|
B2000000
|
|
.ft P
|
|
.fi
|
|
.PP
|
|
These constants are additionally supported on the SPARC architecture:
|
|
.PP
|
|
.nf
|
|
.ft B
|
|
B76800
|
|
B153600
|
|
B307200
|
|
B614400
|
|
.ft P
|
|
.fi
|
|
.PP
|
|
These constants are additionally supported on non-SPARC architectures:
|
|
.PP
|
|
.nf
|
|
.ft B
|
|
B2500000
|
|
B3000000
|
|
B3500000
|
|
B4000000
|
|
.ft P
|
|
.fi
|
|
.PP
|
|
Due to differences between architectures, portable applications should check
|
|
if a particular
|
|
.BI B nnn
|
|
constant is defined prior to using it.
|
|
.PP
|
|
The zero baud rate,
|
|
.BR 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.
|
|
.B CBAUDEX
|
|
is a mask
|
|
for the speeds beyond those defined in POSIX.1 (57600 and above).
|
|
Thus,
|
|
.BR B57600 " & " CBAUDEX
|
|
is nonzero.
|
|
.PP
|
|
Setting the baud rate to a value other than those defined by
|
|
.BI B nnn
|
|
constants is possible via the
|
|
.B TCSETS2
|
|
ioctl; see
|
|
.BR ioctl_tty (2).
|
|
.PP
|
|
.BR cfgetispeed ()
|
|
returns the input baud rate stored in the
|
|
.I termios
|
|
structure.
|
|
.PP
|
|
.BR cfsetispeed ()
|
|
sets the input baud rate stored in the
|
|
.I termios
|
|
structure to
|
|
.IR speed ,
|
|
which must be specified as one of the
|
|
.BI B nnn
|
|
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.
|
|
.PP
|
|
.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
|
|
.BR cfgetispeed ()
|
|
returns the input baud rate stored in the
|
|
\fItermios\fP
|
|
structure.
|
|
.PP
|
|
.BR cfgetospeed ()
|
|
returns the output baud rate stored in the \fItermios\fP structure.
|
|
.PP
|
|
All other functions return:
|
|
.IP 0
|
|
on success.
|
|
.IP \-1
|
|
on failure and set
|
|
.I errno
|
|
to indicate the error.
|
|
.PP
|
|
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
|
|
For an explanation of the terms used in this section, see
|
|
.BR attributes (7).
|
|
.nh
|
|
.ad l
|
|
.nh
|
|
.TS
|
|
allbox;
|
|
lbx lb lb
|
|
l l l.
|
|
Interface Attribute Value
|
|
T{
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.BR tcgetattr (),
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.BR tcsetattr (),
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.BR tcdrain (),
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.BR tcflush (),
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.BR tcflow (),
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.BR tcsendbreak (),
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.BR cfmakeraw (),
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.BR cfgetispeed (),
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.BR cfgetospeed (),
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.BR cfsetispeed (),
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.BR cfsetospeed (),
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.BR cfsetspeed ()
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|
T} Thread safety MT-Safe
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.TE
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.hy
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.ad
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.sp 1
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.\" FIXME: The markings are different from that in the glibc manual.
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.\" markings in glibc manual are more detailed:
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.\"
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.\" tcsendbreak: MT-Unsafe race:tcattr(filedes)/bsd
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.\" tcflow: MT-Unsafe race:tcattr(filedes)/bsd
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.\"
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.\" glibc manual says /bsd indicate the preceding marker only applies
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.\" when the underlying kernel is a BSD kernel.
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.\" So, it is safety in Linux kernel.
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.hy
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.SH CONFORMING TO
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.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.
|
|
.PP
|
|
.BR cfmakeraw ()
|
|
and
|
|
.BR cfsetspeed ()
|
|
are nonstandard, but available on the BSDs.
|
|
.SH NOTES
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|
UNIX\ V7 and several later systems have a list of baud rates
|
|
where after the values
|
|
.BR B0
|
|
through
|
|
.B B9600
|
|
one finds the two constants
|
|
.BR EXTA ,
|
|
.B EXTB
|
|
("External A" and "External B").
|
|
Many systems extend the list with much higher baud rates.
|
|
.PP
|
|
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 BUGS
|
|
.\" kernel 77e5bff1640432f28794a00800955e646dcd7455
|
|
.\" glibc 573963e32ffac46d9891970ddebde2ac3212c5c0
|
|
On the Alpha architecture before Linux 4.16 (and glibc before 2.28), the
|
|
.B XTABS
|
|
value was different from
|
|
.B TAB3
|
|
and it was ignored by the
|
|
.B N_TTY
|
|
line discipline code of the terminal driver as a result
|
|
(because as it wasn't part of the
|
|
.B TABDLY
|
|
mask).
|
|
.SH SEE ALSO
|
|
.BR reset (1),
|
|
.BR setterm (1),
|
|
.BR stty (1),
|
|
.BR tput (1),
|
|
.BR tset (1),
|
|
.BR tty (1),
|
|
.BR ioctl_console (2),
|
|
.BR ioctl_tty (2),
|
|
.BR setserial (8)
|