stty



STTY(1)                     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
     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 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.

   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 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.

   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)
                 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, 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 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 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 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.

   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.

     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.

   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.


EXIT STATUS

     The stty utility exits 0 on success, and >0 if an error occurs.


SEE ALSO

     termios(4), tty(4)


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 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.


HISTORY

     A stty command appeared in Version 2 AT&T UNIX.

OpenBSD 6.4                     August 20, 2016                    OpenBSD 6.4

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