Updated: 2022/Sep/29

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STTY(1)                     General Commands Manual                    STTY(1)

     stty - set options for a terminal device interface

     stty [-a | -e | -g] [-f file] [operand ...]

     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

     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 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(), 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

   Control Modes
     Control mode flags affect hardware characteristics associated with the
     terminal.  This corresponds to the c_cflag of the termios(4) 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 number, if possible.  If the baud
                 rate is set to zero, modem control is no longer asserted;
                 this will normally hang up the line, including on ptys and
                 other devices not physically connected to modems.

     ispeed number
                 Set terminal input baud rate to number, 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 number, if possible.  If the
                 output baud rate is set to zero, modem control is no longer

     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 RTS/CTS flow control.

     cdtrcts (-cdtrcts)
                 Enable DTR/CTS flow control (if supported).

   Input Modes
     This corresponds to the c_iflag of the termios(4) 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.

     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(4) 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.

     oxtabs (-oxtabs)
                 Expand (do not expand) tabs to spaces on output.

     onocr (-onocr)
                 Do not (do) output CRs at column zero.

     onlret (-onlret)
                 On the terminal NL performs (does not perform) the CR

   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(4) 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

     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

     altwerase (-altwerase)
                 Use (do not use) an alternative word erase algorithm when
                 processing WERASE characters.  This alternative 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

     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

     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 string.  If the string is a
                 single character, then the control character is set to that
                 character.  If the string is the two character sequence "^-"
                 or the string "undef", then the control character is disabled
                 (i.e., set to {_POSIX_VDISABLE}).

                 Recognized control characters:

                       character    Subscript    Description
                       _________    _________    _______________
                       eof          VEOF         EOF character
                       eol          VEOL         EOL character
                       eol2         VEOL2        EOL2 character
                       erase        VERASE       ERASE character
                       werase       VWERASE      WERASE character
                       kill         VKILL        KILL character
                       reprint      VREPRINT     REPRINT character
                       intr         VINTR        INTR character
                       quit         VQUIT        QUIT character
                       susp         VSUSP        SUSP character
                       dsusp        VDSUSP       DSUSP character
                       start        VSTART       START character
                       stop         VSTOP        STOP character
                       lnext        VLNEXT       LNEXT character
                       status       VSTATUS      STATUS character
                       discard      VDISCARD     DISCARD 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

     ek          Reset ERASE and KILL characters back to system defaults.

     sane        Resets all modes to reasonable values for interactive
                 terminal use.

     insane      Sets all modes to random values, which are very likely (but
                 not guaranteed) to be unreasonable for interactive terminal

     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.

     cols number
                 The terminal size is recorded as having number columns.

     columns number
                 An alias for cols.

     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

                       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 utility.

     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.

     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 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 expected to be IEEE Std 1003.2 ("POSIX.2")
     compatible.  The -e and -f flags are extensions to the standard, as are
     the operands mentioned in the control operations section.

     An stty utility appeared in Version 2 AT&T UNIX.

NetBSD 9.99                      May 14, 2022                      NetBSD 9.99