NAME
stty
—
set the options for a terminal device
interface
SYNOPSIS
stty |
[-a | -e |
-g ] [-f
file] [arguments] |
DESCRIPTION
The stty
utility sets or reports on
terminal characteristics for the device that is its standard input. If no
options or arguments are specified, it reports the settings of a subset of
characteristics as well as additional ones if they differ from their default
values. Otherwise it modifies the terminal state according to the specified
arguments. Some combinations of arguments are mutually exclusive on some
terminal types.
The following options are available:
-a
- Display all the current settings for the terminal to standard output as per IEEE Std 1003.2 (“POSIX.2”).
-e
- Display all the current settings for the terminal to standard output in the traditional BSD ``all'' and ``everything'' formats.
-f
- Open and use the terminal named by file rather than
using standard input. The file is opened using the
O_NONBLOCK
flag ofopen
(), making it possible to set or display settings on a terminal that might otherwise block on the open. -g
- Display all the current settings for the terminal to standard output in a
form that may be used as an argument to a subsequent invocation of
stty
to restore the current terminal state as per IEEE Std 1003.2 (“POSIX.2”).
The following arguments are available to set the terminal characteristics:
Control Modes:
Control mode flags affect hardware characteristics associated with the terminal. This corresponds to the c_cflag in the termios structure.
- number
- Set terminal baud rate to the number given, if possible. If the baud rate is set to zero, modem control is no longer asserted.
clocal
(-clocal
)- Assume a line without (with) modem control.
cread
(-cread
)- Enable (disable) the receiver.
crtscts
(-crtscts
)- Enable (disable) RTS/CTS flow control.
cs5 cs6 cs7 cs8
- Select character size, if possible.
cstopb
(-cstopb
)- Use two (one) stop bits per character.
hup
(-hup
)- Same as
hupcl
(-hupcl
). hupcl
(-hupcl
)- Stop asserting modem control (do not stop asserting modem control) on last close.
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 is set to the value of the output baud rate.
ospeed
number- Set terminal output baud rate to the number given, if possible. If the output baud rate is set to zero, modem control is no longer asserted.
parenb
(-parenb
)- Enable (disable) parity generation and detection.
parodd
(-parodd
)- Select odd (even) parity.
speed
number- This sets both
ispeed
andospeed
to number.
Input Modes:
This corresponds to the c_iflag in the termios structure.
brkint
(-brkint
)- Signal (do not signal)
INTR
on break. icrnl
(-icrnl
)- Map (do not map)
CR
toNL
on input. ignbrk
(-ignbrk
)- Ignore (do not ignore) break on input.
igncr
(-igncr
)- Ignore (do not ignore)
CR
on input. ignpar
(-ignpar
)- Ignore (do not ignore) characters with parity errors.
imaxbel
(-imaxbel
)- The system imposes a limit of
MAX_INPUT
(currently 255) characters in the input queue. Ifimaxbel
is set and the input queue limit has been reached, subsequent input causes the system to send an ASCII BEL character to the output queue (the terminal beeps at you). Otherwise, ifimaxbel
is unset and the input queue is full, the next input character causes the entire input and output queues to be discarded. inlcr
(-inlcr
)- Map (do not map)
NL
toCR
on input. inpck
(-inpck
)- Enable (disable) input parity checking.
istrip
(-istrip
)- Strip (do not strip) input characters to seven bits.
iutf8
(-iutf8
)- Assume input characters are UTF-8 encoded.
ixany
(-ixany
)- Allow any character (allow only
START
) to restart output. ixoff
(-ixoff
)- Request that the system send (not send)
START/STOP
characters when the input queue is nearly empty/full. ixon
(-ixon
)- Enable (disable)
START/STOP
output control. Output from the system is stopped when the system receivesSTOP
and started when the system receivesSTART
, or ifixany
is set, any character restarts output. parmrk
(-parmrk
)- Mark (do not mark) characters with parity errors.
Output Modes:
This corresponds to the c_oflag of the termios structure.
bs0 bs1
- Select the style of delay for backspaces (e.g., set BSDLY to BS0).
cr0 cr1 cr2 cr3
- Select the style of delay for carriage returns (e.g., set CRDLY to CR0).
ff0 ff1
- Select the style of delay for form feeds (e.g., set FFDLY to FF0).
nl0 nl1
- Select the style of delay for newlines (e.g., set NLDLY to NL0).
ocrnl
(-ocrnl
)- Map (do not map) carriage return to newline on output.
ofdel
(-odell
)- Use DELs (NULs) as fill characters.
ofill
(-ofill
)- Use fill characters (use timing) for delays.
onlcr
(-onlcr
)- Map (do not map)
NL
toCR-NL
on output. onlret
(-onlret
)- On the terminal, NL performs (does not perform) the CR function.
onocr
(-onocr
)- Do not (do) output CRs at column zero.
opost
(-opost
)- Post-process output (do not post-process output; ignore all other output modes).
oxtabs
(-oxtabs
)- Expand (do not expand) tabs to spaces on output.
tab0 tab1 tab2 tab3
- Select the style of delay for horizontal tabs (e.g., set TABDLY to TAB0).
tabs
(-tabs
)- Same as
tab0
(tab3
). vt0 vt1
- Select the style of delay for vertical tabs (e.g., set VTDLY to VT0).
Local Modes:
Local mode flags (lflags) affect various and sundry characteristics of terminal processing. Historically the term "local" pertained to new job control features implemented by Jim Kulp on a Pdp 11/70 at IIASA. Later, the driver ran on the first VAX at Evans Hall, UC Berkeley, where the job control details were greatly modified, but the structure definitions and names remained essentially unchanged. The second interpretation of the 'l' in lflag is ``line discipline flag'', which corresponds to the c_lflag of the termios structure.
altwerase
(-altwerase
)- Use (do not use) an alternate word erase algorithm when processing
WERASE
characters. This alternate algorithm considers sequences of alphanumeric/underscores as words. It also skips the first preceding character in its classification (as a convenience, since the one preceding character could have been erased with simply anERASE
character.) echo
(-echo
)- Echo back (do not echo back) every character typed.
echoctl
(-echoctl
)- If
echoctl
is set, echo control characters as ^X. Otherwise, control characters echo as themselves. echoe
(-echoe
)- The
ERASE
character shall (shall not) visually erase the last character in the current line from the display, if possible. echok
(-echok
)- Echo (do not echo)
NL
afterKILL
character. echoke
(-echoke
)- The
KILL
character shall (shall not) visually erase the current line from the display, if possible. echonl
(-echonl
)- Echo (do not echo)
NL
, even if echo is disabled. echoprt
(-echoprt
)- For printing terminals. If set, echo erased characters backwards within ``\'' and ``/''. Otherwise, disable this feature.
flusho
(-flusho
)- Indicates output is (is not) being discarded.
icanon
(-icanon
)- Enable (disable) canonical input (
ERASE
andKILL
processing). iexten
(-iexten
)- Enable (disable) any implementation-defined special control characters
that are not currently controlled by
icanon
,isig
,ixoff
, orixon
. isig
(-isig
)- Enable (disable) the checking of characters against the special control
characters
INTR
,QUIT
, andSUSP
. mdmbuf
(-mdmbuf
)- If set, flow control output based on condition of Carrier Detect.
Otherwise, writes return an error if Carrier Detect is low (and Carrier is
not being ignored with the
CLOCAL
flag.) noflsh
(-noflsh
)- Disable (enable) flush after
INTR
,QUIT
, orSUSP
. pendin
(-pendin
)- Indicates input is (is not) pending after a switch from non-canonical to canonical mode and will be re-input when a read becomes pending or more input arrives.
tostop
(-tostop
)- Send (do not send)
SIGTTOU
for background output. This causes background jobs to stop if they attempt terminal output.
Control Characters:
- control-character string
- Set control-character to
string. If string is a single character, the control
character is set to that character. If string is the two character
sequence "^-" or the string "undef" the control
character is disabled (i.e., set to
{
_POSIX_VDISABLE
}.)Recognized control-characters:
control- character Subscript Description _________ _________ _______________ eof VEOF EOF character eol VEOL EOL character eol2 VEOL2 EOL2 character erase VERASE ERASE character erase2 VERASE2 ERASE2 character werase VWERASE WERASE 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 dsusp VDSUSP DSUSP character lnext VLNEXT LNEXT character reprint VREPRINT REPRINT character status VSTATUS STATUS character min
numbertime
number- Set the value of min or time to number.
MIN
andTIME
are 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. cols
number- Same as
columns
. columns
number- The terminal size is recorded as having number columns.
crt
(-crt
)- Set (disable) all modes suitable for a CRT display device.
dec
- Set modes suitable for users of Digital Equipment Corporation systems
(
ERASE
,KILL
, andINTR
characters are set to ^?, ^U, and ^C;ixany
is disabled, andcrt
is enabled.) ek
- Reset
ERASE
,ERASE2
, andKILL
characters back to system defaults. -evenp
- Same as
-oddp
and-parity
. evenp
- Enable
parenb
andcs7
; disableparodd
. extproc
(-extproc
)- If set, this flag indicates that some amount of terminal processing is being performed by either the terminal hardware or by the remote side connected to a pty.
kerninfo
(-kerninfo
)- Enable (disable) the system generated status line associated with
processing a
STATUS
character (usually set to ^T). The status line consists of the system load average, the current command name, its process ID, the event the process is waiting on (or the status of the process), the user and system times, percent cpu, and current memory usage. nl
(-nl
)- Enable (disable)
icrnl
. In addition,-nl
unsetsinlcr
andigncr
. -oddp
- Same as
-evenp
and-parity
. oddp
- Enable
parenb
,cs7
, andparodd
. -parity
- Disable
parenb
; setcs8
. parity
- Same as
evenp
. raw
(-raw
)- If set, change the modes of the terminal so that no input or output
processing is performed. If unset, change the modes of the terminal to
some reasonable state that performs input and output processing. Note that
since the terminal driver no longer has a single
RAW
bit, it is not possible to intuit what flags were set prior to settingraw
. This means that unsettingraw
may not put back all the setting that were previously in effect. To set the terminal into a raw state and then accurately restore it, the following shell code is recommended:save_state=$(stty -g) stty raw ... stty "$save_state"
rows
number- The terminal size is recorded as having number rows.
sane
- Resets all modes to reasonable values for interactive terminal use.
size
- The size of the terminal is printed as two numbers on a single line, first rows, then columns.
tty
- Set the line discipline to the standard terminal line discipline
TTYDISC
.
Compatibility Modes:
These modes remain for compatibility with the previous version of
the stty
command.
all
- Reports all the terminal modes as with
stty
-a
except that the control characters are printed in a columnar format. brk
value- Same as the control character
eol
. cbreak
- If set, enables
brkint
,ixon
,imaxbel
,opost
,isig
,iexten
, and-icanon
. If unset, same assane
. cooked
- Same as
sane
. crtbs
(-crtbs
)- Same as
echoe
. crterase
(-crterase
)- Same as
echoe
. crtkill
(-crtkill
)- Same as
echoke
. ctlecho
(-ctlecho
)- Same as
echoctl
. decctlq
(-decctlq
)- The converse of
ixany
. everything
- Same as
all
. flush
value- Same as the control character
discard
. litout
(-litout
)- The converse of
opost
. new
- Same as
tty
. newcrt
(-newcrt
)- Same as
crt
. old
- Same as
tty
. oxtabs
(-oxtabs
)- Expand(do not expand) tabs to spaces on output.
pass8
- The converse of
parity
. prterase
(-prterase
)- Same as
echoprt
. rprnt
value- Same as the control character
reprint
. tabs
(-tabs
)- The converse of
oxtabs
. tandem
(-tandem
)- Same as
ixoff
.
EXIT STATUS
The stty
utility exits 0 on
success, and >0 if an error occurs.
LEGACY DESCRIPTION
In legacy operation, the bs[01]
,
cr[0-3]
, ff[01]
,
nl[01]
, tab[0-3]
, and
vt[01]
control modes are not accepted, nor are
ocrnl
(-ocrnl
),
ofdel
(-ofdel
),
ofill
(-ofill
),
onlret
(-onlret
), and
onocr
(-onocr
).
For more information about legacy mode, see compat(5).
SEE ALSO
STANDARDS
The stty
utility is expected to be
IEEE Std 1003.2 (“POSIX.2”)
compatible. The flags -e
and
-f
are extensions to the standard.
HISTORY
A stty
command appeared in
Version 2 AT&T UNIX.