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|
stty(P) stty(P)
NAME
stty - set the options for a terminal
SYNOPSIS
stty [ -a| -g]
stty operands
DESCRIPTION
The stty utility shall set or report on terminal I/O
characteristics for the device that is its standard
input. Without options or operands specified, it shall
report the settings of certain characteristics, usually
those that differ from implementation-defined defaults.
Otherwise, it shall modify the terminal state according
to the specified operands. Detailed information about
the modes listed in the first five groups below are
described in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Terminal
Interface. Operands in the Combination Modes group (see
Combination Modes ) are implemented using operands in
the previous groups. Some combinations of operands are
mutually-exclusive on some terminal types; the results
of using such combinations are unspecified.
Typical implementations of this utility require a commu-
nications line configured to use the termios interface
defined in the System Interfaces volume of
IEEE Std 1003.1-2001. On systems where none of these
lines are available, and on lines not currently config-
ured to support the termios interface, some of the oper-
ands need not affect terminal characteristics.
OPTIONS
The stty utility shall conform to the Base Definitions
volume of IEEE Std 1003.1-2001, Section 12.2, Utility
Syntax Guidelines.
The following options shall be supported:
-a Write to standard output all the current settings
for the terminal.
-g Write to standard output all the current settings
in an unspecified form that can be used as argu-
ments to another invocation of the stty utility
on the same system. The form used shall not con-
tain any characters that would require quoting to
avoid word expansion by the shell; see Word
Expansions .
OPERANDS
The following operands shall be supported to set the
terminal characteristics.
Control Modes
parenb (-parenb)
Enable (disable) parity generation and detection.
This shall have the effect of setting (not set-
ting) PARENB in the termios c_cflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General
Terminal Interface.
parodd (-parodd)
Select odd (even) parity. This shall have the
effect of setting (not setting) PARODD in the
termios c_cflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
cs5 cs6 cs7 cs8
Select character size, if possible. This shall
have the effect of setting CS5, CS6, CS7, and
CS8, respectively, in the termios c_cflag field,
as defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
number Set terminal baud rate to the number given, if
possible. If the baud rate is set to zero, the
modem control lines shall no longer be asserted.
This shall have the effect of setting the input
and output termios baud rate values as defined in
the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
ispeed number
Set terminal input baud rate to the number given,
if possible. If the input baud rate is set to
zero, the input baud rate shall be specified by
the value of the output baud rate. This shall
have the effect of setting the input termios baud
rate values as defined in the Base Definitions
volume of IEEE Std 1003.1-2001, Chapter 11, Gen-
eral Terminal Interface.
ospeed number
Set terminal output baud rate to the number
given, if possible. If the output baud rate is
set to zero, the modem control lines shall no
longer be asserted. This shall have the effect of
setting the output termios baud rate values as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
hupcl (-hupcl)
Stop asserting modem control lines (do not stop
asserting modem control lines) on last close.
This shall have the effect of setting (not set-
ting) HUPCL in the termios c_cflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
hup (-hup)
Equivalent to hupcl( -hupcl).
cstopb (-cstopb)
Use two (one) stop bits per character. This shall
have the effect of setting (not setting) CSTOPB
in the termios c_cflag field, as defined in the
Base Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface.
cread (-cread)
Enable (disable) the receiver. This shall have
the effect of setting (not setting) CREAD in the
termios c_cflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
clocal (-clocal)
Assume a line without (with) modem control. This
shall have the effect of setting (not setting)
CLOCAL in the termios c_cflag field, as defined
in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
It is unspecified whether stty shall report an error if
an attempt to set a Control Mode fails.
Input Modes
ignbrk (-ignbrk)
Ignore (do not ignore) break on input. This shall
have the effect of setting (not setting) IGNBRK
in the termios c_iflag field, as defined in the
Base Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface.
brkint (-brkint)
Signal (do not signal) INTR on break. This shall
have the effect of setting (not setting) BRKINT
in the termios c_iflag field, as defined in the
Base Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface.
ignpar (-ignpar)
Ignore (do not ignore) bytes with parity errors.
This shall have the effect of setting (not set-
ting) IGNPAR in the termios c_iflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
parmrk (-parmrk)
Mark (do not mark) parity errors. This shall have
the effect of setting (not setting) PARMRK in the
termios c_iflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
inpck (-inpck)
Enable (disable) input parity checking. This
shall have the effect of setting (not setting)
INPCK in the termios c_iflag field, as defined in
the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
istrip (-istrip)
Strip (do not strip) input characters to seven
bits. This shall have the effect of setting (not
setting) ISTRIP in the termios c_iflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
inlcr (-inlcr)
Map (do not map) NL to CR on input. This shall
have the effect of setting (not setting) INLCR in
the termios c_iflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
igncr (-igncr)
Ignore (do not ignore) CR on input. This shall
have the effect of setting (not setting) IGNCR in
the termios c_iflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
icrnl (-icrnl)
Map (do not map) CR to NL on input. This shall
have the effect of setting (not setting) ICRNL in
the termios c_iflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
ixon (-ixon)
Enable (disable) START/STOP output control. Out-
put from the system is stopped when the system
receives STOP and started when the system
receives START. This shall have the effect of
setting (not setting) IXON in the termios c_iflag
field, as defined in the Base Definitions volume
of IEEE Std 1003.1-2001, Chapter 11, General Ter-
minal Interface.
ixany (-ixany)
Allow any character to restart output. This shall
have the effect of setting (not setting) IXANY in
the termios c_iflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
ixoff (-ixoff)
Request that the system send (not send) STOP
characters when the input queue is nearly full
and START characters to resume data transmission.
This shall have the effect of setting (not set-
ting) IXOFF in the termios c_iflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
Output Modes
opost (-opost)
Post-process output (do not post-process output;
ignore all other output modes). This shall have
the effect of setting (not setting) OPOST in the
termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
ocrnl (-ocrnl)
Map (do not map) CR to NL on output This shall
have the effect of setting (not setting) OCRNL in
the termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
onocr (-onocr)
Do not (do) output CR at column zero. This shall
have the effect of setting (not setting) ONOCR in
the termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
onlret (-onlret)
The terminal newline key performs (does not per-
form) the CR function. This shall have the
effect of setting (not setting) ONLRET in the
termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface.
ofill (-ofill)
Use fill characters (use timing) for delays. This
shall have the effect of setting (not setting)
OFILL in the termios c_oflag field, as defined in
the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
ofdel (-ofdel)
Fill characters are DELs (NULs). This shall have
the effect of setting (not setting) OFDEL in the
termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
cr0 cr1 cr2 cr3
Select the style of delay for CRs. This shall
have the effect of setting CRDLY to CR0, CR1,
CR2, or CR3, respectively, in the termios c_oflag
field, as defined in the Base Definitions volume
of IEEE Std 1003.1-2001, Chapter 11, General Ter-
minal Interface.
nl0 nl1
Select the style of delay for NL. This shall have
the effect of setting NLDLY to NL0 or NL1,
respectively, in the termios c_oflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
tab0 tab1 tab2 tab3
Select the style of delay for horizontal tabs.
This shall have the effect of setting TABDLY to
TAB0, TAB1, TAB2, or TAB3, respectively, in the
termios c_oflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface. Note that
TAB3 has the effect of expanding <tab>s to
<space>s.
tabs (-tabs)
Synonym for tab0 ( tab3).
bs0 bs1
Select the style of delay for backspaces. This
shall have the effect of setting BSDLY to BS0 or
BS1, respectively, in the termios c_oflag field,
as defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
ff0 ff1
Select the style of delay for form-feeds. This
shall have the effect of setting FFDLY to FF0 or
FF1, respectively, in the termios c_oflag field,
as defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
vt0 vt1
Select the style of delay for vertical-tabs. This
shall have the effect of setting VTDLY to VT0 or
VT1, respectively, in the termios c_oflag field,
as defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
Local Modes
isig (-isig)
Enable (disable) the checking of characters
against the special control characters INTR,
QUIT, and SUSP. This shall have the effect of
setting (not setting) ISIG in the termios c_lflag
field, as defined in the Base Definitions volume
of IEEE Std 1003.1-2001, Chapter 11, General Ter-
minal Interface.
icanon (-icanon)
Enable (disable) canonical input (ERASE and KILL
processing). This shall have the effect of set-
ting (not setting) ICANON in the termios c_lflag
field, as defined in the Base Definitions volume
of IEEE Std 1003.1-2001, Chapter 11, General Ter-
minal Interface.
iexten (-iexten)
Enable (disable) any implementation-defined spe-
cial control characters not currently controlled
by icanon, isig, ixon, or ixoff. This shall have
the effect of setting (not setting) IEXTEN in the
termios c_lflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
echo (-echo)
Echo back (do not echo back) every character
typed. This shall have the effect of setting (not
setting) ECHO in the termios c_lflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
echoe (-echoe)
The ERASE character visually erases (does not
erase) the last character in the current line
from the display, if possible. This shall have
the effect of setting (not setting) ECHOE in the
termios c_lflag field, as defined in the Base
Definitions volume of IEEE Std 1003.1-2001, Chap-
ter 11, General Terminal Interface.
echok (-echok)
Echo (do not echo) NL after KILL character. This
shall have the effect of setting (not setting)
ECHOK in the termios c_lflag field, as defined in
the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
echonl (-echonl)
Echo (do not echo) NL, even if echo is disabled.
This shall have the effect of setting (not set-
ting) ECHONL in the termios c_lflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
noflsh (-noflsh)
Disable (enable) flush after INTR, QUIT, SUSP.
This shall have the effect of setting (not set-
ting) NOFLSH in the termios c_lflag field, as
defined in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface.
tostop (-tostop)
Send SIGTTOU for background output. This shall
have the effect of setting (not setting) TOSTOP
in the termios c_lflag field, as defined in the
Base Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface.
Special Control Character Assignments
<control>-character string
Set <control>-character to string. If <con-
trol>-character is one of the character sequences
in the first column of the following table, the
corresponding Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Termi-
nal Interface control character from the second
column shall be recognized. This has the effect
of setting the corresponding element of the
termios c_cc array (see the Base Definitions vol-
ume of IEEE Std 1003.1-2001, Chapter 13, Headers,
<termios.h>).
Table: Control Character Names in stty
Control Character c_cc Subscript Description
eof VEOF EOF character
eol VEOL EOL character
erase VERASE ERASE character
intr VINTR INTR character
kill VKILL KILL character
quit VQUIT QUIT character
susp VSUSP SUSP character
start VSTART START character
stop VSTOP STOP character
If string is a single character, the control character
shall be set to that character. If string is the two-
character sequence "^-" or the string undef, the control
character shall be set to _POSIX_VDISABLE , if it is in
effect for the device; if _POSIX_VDISABLE is not in
effect for the device, it shall be treated as an error.
In the POSIX locale, if string is a two-character
sequence beginning with circumflex ( '^' ), and the sec-
ond character is one of those listed in the "^c" column
of the following table, the control character shall be
set to the corresponding character value in the Value
column of the table. Table: Circumflex Control Charac-
ters in stty
^c Value ^c Value ^c Value
a, A <SOH> l, L <FF> w, W <ETB>
b, B <STX> m, M <CR> x, X <CAN>
c, C <ETX> n, N <SO> y, Y <EM>
d, D <EOT> o, O <SI> z, Z <SUB>
e, E <ENQ> p, P <DLE> [ <ESC>
f, F <ACK> q, Q <DC1> \ <FS>
g, G <BEL> r, R <DC2> ] <GS>
h, H <BS> s, S <DC3> ^ <RS>
i, I <HT> t, T <DC4> _ <US>
j, J <LF> u, U <NAK> ? <DEL>
k, K <VT> v, V <SYN>
min number
Set the value of MIN to number. MIN is used in
non-canonical mode input processing ( icanon).
time number
Set the value of TIME to number. TIME is used in
non-canonical mode input processing ( icanon).
Combination Modes
saved settings
Set the current terminal characteristics to the
saved settings produced by the -g option.
evenp or parity
Enable parenb and cs7; disable parodd.
oddp
Enable parenb, cs7, and parodd.
-parity, -evenp, or -oddp
Disable parenb, and set cs8.
raw (-raw or cooked)
Enable (disable) raw input and output. Raw mode
shall be equivalent to setting:
stty cs8 erase ^- kill ^- intr ^- \
quit ^- eof ^- eol ^- -post -inpck
nl (-nl)
Disable (enable) icrnl. In addition, -nl unsets
inlcr and igncr.
ek Reset ERASE and KILL characters back to system
defaults.
sane
Reset all modes to some reasonable, unspecified,
values.
STDIN
Although no input is read from standard input, standard
input shall be used to get the current terminal I/O
characteristics and to set new terminal I/O characteris-
tics.
INPUT FILES
None.
ENVIRONMENT VARIABLES
The following environment variables shall affect the
execution of stty:
LANG Provide a default value for the internationaliza-
tion variables that are unset or null. (See the
Base Definitions volume of IEEE Std 1003.1-2001,
Section 8.2, Internationalization Variables for
the precedence of internationalization variables
used to determine the values of locale cate-
gories.)
LC_ALL If set to a non-empty string value, override the
values of all the other internationalization
variables.
LC_CTYPE
This variable determines the locale for the
interpretation of sequences of bytes of text data
as characters (for example, single-byte as
opposed to multi-byte characters in arguments)
and which characters are in the class print.
LC_MESSAGES
Determine the locale that should be used to
affect the format and contents of diagnostic mes-
sages written to standard error.
NLSPATH
Determine the location of message catalogs for
the processing of LC_MESSAGES .
ASYNCHRONOUS EVENTS
Default.
STDOUT
If operands are specified, no output shall be produced.
If the -g option is specified, stty shall write to stan-
dard output the current settings in a form that can be
used as arguments to another instance of stty on the
same system.
If the -a option is specified, all of the information as
described in the OPERANDS section shall be written to
standard output. Unless otherwise specified, this infor-
mation shall be written as <space>-separated tokens in
an unspecified format, on one or more lines, with an
unspecified number of tokens per line. Additional
information may be written.
If no options or operands are specified, an unspecified
subset of the information written for the -a option
shall be written.
If speed information is written as part of the default
output, or if the -a option is specified and if the ter-
minal input speed and output speed are the same, the
speed information shall be written as follows:
"speed %d baud;", <speed>
Otherwise, speeds shall be written as:
"ispeed %d baud; ospeed %d baud;", <ispeed>, <ospeed>
In locales other than the POSIX locale, the word baud
may be changed to something more appropriate in those
locales.
If control characters are written as part of the default
output, or if the -a option is specified, control char-
acters shall be written as:
"%s = %s;", <control-character name>, <value>
where <value> is either the character, or some visual
representation of the character if it is non-printable,
or the string undef if the character is disabled.
STDERR
The standard error shall be used only for diagnostic
messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0 The terminal options were read or set success-
fully.
>0 An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
The -g flag is designed to facilitate the saving and
restoring of terminal state from the shell level. For
example, a program may:
saveterm="$(stty -g)" # save terminal state
stty (new settings) # set new state
... # ...
stty $saveterm # restore terminal state
Since the format is unspecified, the saved value is not
portable across systems.
Since the -a format is so loosely specified, scripts
that save and restore terminal settings should use the
-g option.
EXAMPLES
None.
RATIONALE
The original stty description was taken directly from
System V and reflected the System V terminal driver
termio. It has been modified to correspond to the ter-
minal driver termios.
Output modes are specified only for XSI-conformant sys-
tems. All implementations are expected to provide stty
operands corresponding to all of the output modes they
support.
The stty utility is primarily used to tailor the user
interface of the terminal, such as selecting the pre-
ferred ERASE and KILL characters. As an application pro-
gramming utility, stty can be used within shell scripts
to alter the terminal settings for the duration of the
script.
The termios section states that individual disabling of
control characters is possible through the option
_POSIX_VDISABLE. If enabled, two conventions currently
exist for specifying this: System V uses "^-" , and BSD
uses undef. Both are accepted by stty in this volume of
IEEE Std 1003.1-2001. The other BSD convention of using
the letter 'u' was rejected because it conflicts with
the actual letter 'u' , which is an acceptable value for
a control character.
Early proposals did not specify the mapping of "^c" to
control characters because the control characters were
not specified in the POSIX locale character set descrip-
tion file requirements. The control character set is
now specified in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 3, Definitions so the his-
torical mapping is specified. Note that although the
mapping corresponds to control-character key assignments
on many terminals that use the ISO/IEC 646:1991 standard
(or ASCII) character encodings, the mapping specified
here is to the control characters, not their keyboard
encodings.
Since termios supports separate speeds for input and
output, two new options were added to specify each dis-
tinctly.
Some historical implementations use standard input to
get and set terminal characteristics; others use stan-
dard output. Since input from a login TTY is usually
restricted to the owner while output to a TTY is fre-
quently open to anyone, using standard input provides
fewer chances of accidentally (or maliciously) altering
the terminal settings of other users. Using standard
input also allows stty -a and stty -g output to be redi-
rected for later use. Therefore, usage of standard input
is required by this volume of IEEE Std 1003.1-2001.
FUTURE DIRECTIONS
None.
SEE ALSO
Shell Command Language , the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 11, General Terminal
Interface, <termios.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in
electronic form from IEEE Std 1003.1, 2003 Edition,
Standard for Information Technology -- Portable Operat-
ing System Interface (POSIX), The Open Group Base Speci-
fications Issue 6, Copyright (C) 2001-2003 by the Insti-
tute of Electrical and Electronics Engineers, Inc and
The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be
obtained online at http://www.open-
group.org/unix/online.html .
POSIX 2003 stty(P)
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