STTY(1) FreeBSD General Commands Manual STTY(1)
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 of
open(), 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.
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.
rtsdtr (--rtsdtr)
Enable (disable) asserting RTS/DTR on open.
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) characters with parity errors.
parmrk (-parmrk)
Mark (do not mark) characters with 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.
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.
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 to CR-NL on output.
ocrnl (-ocrnl)
Map (do not map) CR to NL on output.
tab0 tab3 Select tab expansion policy. tab0 disables tab expansion,
while tab3 enables it.
onocr (-onocr)
Do not (do) output CRs at column zero.
onlret (-onlret)
On the terminal NL performs (does not perform) the CR
function.
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, 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.
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 number
time number
Set the value of min or time to number. MIN and TIME 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 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, ERASE2, 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.
If the sysctl(8) variable kern.tty_info_kstacks is set to a
non-zero value, the status message also includes the kernel
program stack of the foreground thread.
columns number
The terminal size is recorded as having number columns.
cols number
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.
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 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.
litout (-litout)
The converse of opost.
oxtabs (-oxtabs)
Expand (do not expand) tabs to spaces on output.
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.
EXIT STATUS
The stty utility exits 0 on success, and >0 if an error occurs.
SEE ALSO
resizewin(1), termios(4), pstat(8)
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.
FreeBSD 13.1-RELEASE-p6 October 20, 2018 FreeBSD 13.1-RELEASE-p6
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