STTY(1) BSD General Commands Manual STTY(1)
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 speci-
fied, 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 invo-
cation 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 and ospeed 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 to NL 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. 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.
inlcr (-inlcr)
Map (do not map) NL to CR 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 receives STOP and started when the
system receives START, or if ixany 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 to CR-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 conve-
nience, since the one preceding character could have been erased with simply an ERASE 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 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.
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 and KILL processing).
iexten (-iexten)
Enable (disable) any implementation-defined special control characters that are not currently controlled by icanon, isig, ixoff,
or ixon.
isig (-isig)
Enable (disable) the checking of characters against the special control characters INTR, QUIT, and SUSP.
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, or SUSP.
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 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.
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, and INTR characters are set to ^?, ^U, and
^C; ixany is disabled, and crt is enabled.)
ek Reset ERASE, ERASE2, and KILL characters back to system defaults.
-evenp Same as -oddp and -parity.
evenp Enable parenb and cs7; disable parodd.
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 unsets inlcr and igncr.
-oddp Same as -evenp and -parity.
oddp Enable parenb, cs7, and parodd.
-parity Disable parenb; set cs8.
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 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"
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 as sane.
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.
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.
DIAGNOSTICS
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
termios(4), compat(5)
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.
BSD
April 18, 1994 BSD