stty —
set the
options for a terminal device interface
| stty |
[-a |
-e | -g]
[-f
file]
[operands] |
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 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 and
ospeed 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.
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 to
CR on input.
-
-
- igncr
(-igncr)
- Ignore (do not ignore)
CR on input.
-
-
- icrnl
(-icrnl)
- Map (do not map)
CR to
NL 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 receives
STOP and started when the system
receives START, or if
ixany 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. If imaxbel 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, if imaxbel is unset and the
input queue is full, the next input character causes the entire input and
output queues to be discarded.
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 to
CR-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 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, and
SUSP.
-
-
- icanon
(-icanon)
- Enable (disable) canonical input
(
ERASE and
KILL processing).
-
-
- iexten
(-iexten)
- Enable (disable) any implementation defined special control
characters not currently controlled by
icanon, isig, or
ixon.
-
-
- 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
after KILL 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 an ERASE 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 and
olcuc.
- 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
number
-
- time
number
- Set the value of min or
time to
number.
MIN and
TIME are used in non-canonical mode
input processing (-icanon).
-
-
- 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, -oddp
- Disable parenb and set
cs8.
-
-
- nl
(-nl)
- Enable (disable) icrnl. In
addition, -nl unsets
inlcr and
igncr.
-
-
- ek
- Reset
ERASE and
KILL 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, and
INTR characters are set to ^?, ^U, and
^C; ixany is disabled, and
crt 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 setting raw.
This means that unsetting raw 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.
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 as
sane.
-
-
- 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 and
xcase.
-
-
- 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.
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 when ixon is set.
-
-
- ostop
- Performs a “stop output” operation, as
normally done by an incoming
STOP
character when ixon is set.
The
stty utility exits 0 on success,
and >0 if an error occurs.
termios(4),
tty(4)
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 characters 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.
A
stty command appeared in
Version 2 AT&T UNIX.
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