NAME
stty
—
set the options for a terminal device
interface
SYNOPSIS
stty |
[-a | -e |
-g ] [-f
file] [operands] |
DESCRIPTION
The stty
utility sets or reports on
terminal characteristics for the device that is its standard input. If no
options or operands 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 options are as follows:
-a
- Display all the current settings for the terminal to standard output.
-e
- Display all the current settings for the terminal to standard output in the traditional BSD “all” and “everything” formats.
-f
file- Open and use the terminal named by file rather than
using standard input. The file is opened using the
O_NONBLOCK
flag of open(2), 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. The output does not contain any characters that require quoting, to avoid word expansion by the shell.
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.
parenb
(-parenb
)- Enable (disable) parity generation and detection.
parodd
(-parodd
)- Select odd (even) parity.
cs5 cs6 cs7 cs8
- Select character size, if possible.
- 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.
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.
speed
number- This sets both
ispeed
andospeed
to number. hupcl
(-hupcl
)- Stop asserting modem control (do not stop asserting modem control) on last close.
hup
(-hup
)- Same as
hupcl
(-hupcl
). cstopb
(-cstopb
)- Use two (one) stop bits per character.
cread
(-cread
)- Enable (disable) the receiver.
clocal
(-clocal
)- Assume a line without (with) modem control.
crtscts
(-crtscts
)- Enable (disable) RTS/CTS flow control.
Input modes
This corresponds to the c_iflag
in the
termios structure.
ignbrk
(-ignbrk
)- Ignore (do not ignore) break on input.
brkint
(-brkint
)- Signal (do not signal)
INTR
on break. ignpar
(-ignpar
)- Ignore (do not ignore) parity errors.
parmrk
(-parmrk
)- Mark (do not mark) parity errors.
inpck
(-inpck
)- Enable (disable) input parity checking.
istrip
(-istrip
)- Strip (do not strip) input characters to seven bits.
inlcr
(-inlcr
)- Map (do not map)
NL
toCR
on input. igncr
(-igncr
)- Ignore (do not ignore)
CR
on input. icrnl
(-icrnl
)- Map (do not map)
CR
toNL
on input. iuclc
(-iuclc
)- Translate (do not translate) upper case to lower case on input.
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. ixoff
(-ixoff
)- Request that the system send (not send)
START/STOP
characters when the input queue is nearly empty/full. ixany
(-ixany
)- Allow any character (allow only
START
) to restart output. 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.
Output modes
This corresponds to the c_oflag
of the
termios structure.
opost
(-opost
)- Post-process output (do not post-process output; ignore all other output modes).
onlcr
(-onlcr
)- Map (do not map)
NL
toCR-NL
on output. ocrnl
(-ocrnl
)- Translate (do not translate) carriage return to newline on output.
onocr
(-onocr
)- Carriage return is not output (is output) at column 0.
onlret
(-onlret
)- Newline performs (does not perform) carriage return on output.
olcuc
(-olcuc
)- Translate (do not translate) lower case to upper case on output.
oxtabs
(-oxtabs
)- Expand (do not expand) tabs to spaces on output.
onoeot
(-onoeot
)- Discard (do not discard) EOFs on output.
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.
isig
(-isig
)- Enable (disable) the checking of characters against the special control
characters
INTR
,QUIT
, andSUSP
. icanon
(-icanon
)- Enable (disable) canonical input (
ERASE
andKILL
processing). iexten
(-iexten
)- Enable (disable) any implementation defined special control characters not
currently controlled by
icanon
,isig
, orixon
. echo
(-echo
)- Echo back (do not echo back) every character typed.
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. echoctl
(-echoctl
)- If
echoctl
is set, echo control characters as ‘^X
’. Otherwise control characters echo as themselves. echoprt
(-echoprt
)- For printing terminals. If set, echo erased characters backwards within
‘
\
’ and ‘/
’. Otherwise, disable this feature. noflsh
(-noflsh
)- Disable (enable) flush after
INTR
,QUIT
,SUSP
. tostop
(-tostop
)- Send (do not send)
SIGTTOU
for background output. This causes background jobs to stop if they attempt terminal output. 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). 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). flusho
(-flusho
)- Indicates output is (is not) being discarded.
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.
xcase
(-xcase
)- Upper and lower case is (is not) handled canonically on input and output
with
iuclc
andolcuc
.
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 Subscript Description character eof VEOF
EOF character eol VEOL
EOL character eol2 VEOL2
EOL2 character erase VERASE
ERASE 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
ortime
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. evenp
orparity
- Enable
parenb
andcs7
; disableparodd
. oddp
- Enable
parenb
,cs7
, andparodd
. -parity
,-evenp
,-oddp
- Disable
parenb
and setcs8
. nl
(-nl
)- Enable (disable)
icrnl
. In addition,-nl
unsetsinlcr
andigncr
. ek
- Reset
ERASE
andKILL
characters back to system defaults. sane
- Resets all modes to reasonable values for interactive terminal use.
tty
- Set the line discipline to the standard terminal line discipline
TTYDISC
. crt
(-crt
)- Set (disable) all modes suitable for a CRT display device.
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. columns
number- The terminal size is recorded as having number columns.
cols
number- This is an alias for
columns
. rows
number- The terminal size is recorded as having number rows.
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). 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.
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"
size
- The size of the terminal is printed as two numbers on a single line, first rows, then columns.
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. everything
- Same as
all
. cooked
- Same as
sane
. cbreak
- If set, enables
brkint
,ixon
,imaxbel
,opost
,isig
,iexten
, and-icanon
. If unset, same assane
. new
- Same as
tty
. old
- Same as
tty
. newcrt
(-newcrt
)- Same as
crt
. pass8
- The converse of
parity
. tandem
(-tandem
)- Same as
ixoff
. decctlq
(-decctlq
)- The converse of
ixany
. crterase
(-crterase
)- Same as
echoe
. crtbs
(-crtbs
)- Same as
echoe
. crtkill
(-crtkill
)- Same as
echoke
. ctlecho
(-ctlecho
)- Same as
echoctl
. prterase
(-prterase
)- Same as
echoprt
. lcase
(-lcase
)- Same as
iuclc
,olcuc
andxcase
. litout
(-litout
)- The converse of
opost
. tabs
(-tabs
)- The converse of
oxtabs
. brk
value- Same as the control character
eol
. flush
value- Same as the control character
discard
. rprnt
value- Same as the control character
reprint
.
Control operations
These operations are not modes, but rather commands to be performed by the tty layer.
ostart
- Performs a “start output” operation, as normally done by an
incoming
START
character whenixon
is set. ostop
- Performs a “stop output” operation, as normally done by an
incoming
STOP
character whenixon
is set.
EXIT STATUS
The stty
utility exits 0 on
success, and >0 if an error occurs.
SEE ALSO
STANDARDS
The stty
utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
specification.
The flags [-ef
], the operands
altwerase
, cols
,
columns
, crt
,
crtscts
, dec
,
echoke
, extproc
,
flusho
, imaxbel
,
kerninfo
, mdmbuf
,
onlcr
, onoeot
,
ostart
, ostop
,
oxtabs
, pendin
,
rows
, size
,
speed
, and tty
, and the
control charcters eol2, dsusp, lnext, reprint, status, and werase are all
extensions to that specification.
The operands iuclc
,
olcuc
, and xcase
are marked
by IEEE Std 1003.1-2008 (“POSIX.1”) as
legacy items; the operands listed in
Compatibility modes can also
be considered legacy.
The operands bs0-1
,
cr0-3
, ff0-1
,
nl0-1
, ocrnl
,
ofdel
, ofill
,
onlret
, onocr
,
raw
, tab0-3
,
tabs
, and vt0-1
are marked
by IEEE Std 1003.1-2008 (“POSIX.1”) as
being an X/Open System Interfaces option. Of those, only
ocrnl
, onlret
,
onocr
, raw
, and
tabs
are supported by this implementation of
stty
, and behaviour for tabs
differs.
HISTORY
A stty
command appeared in
Version 3 AT&T UNIX.