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STTY(1P)                   POSIX Programmer's Manual                  STTY(1P)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may dif-
       fer (consult the corresponding Linux manual page for details of Linux behavior), or the interface  may  not  be
       implemented on Linux.

NAME
       stty - set the options for a terminal

SYNOPSIS
       stty [ -a| -g]

       stty operands


DESCRIPTION
       The stty utility shall set or report on terminal I/O characteristics for the device that is its standard input.
       Without options or operands specified, it shall report the settings of certain characteristics,  usually  those
       that  differ  from  implementation-defined defaults. Otherwise, it shall modify the terminal state according to
       the specified operands. Detailed information about the  modes  listed  in  the  first  five  groups  below  are
       described  in  the  Base  Definitions  volume  of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.
       Operands in the Combination Modes group (see Combination Modes ) are implemented using operands in the previous
       groups.  Some combinations of operands are mutually-exclusive on some terminal types; the results of using such
       combinations are unspecified.

       Typical implementations of this utility require a communications line configured to use the  termios  interface
       defined  in  the  System  Interfaces  volume  of IEEE Std 1003.1-2001. On systems where none of these lines are
       available, and on lines not currently configured to support the termios interface, some of  the  operands  need
       not affect terminal characteristics.

OPTIONS
       The  stty  utility  shall conform to the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2, Utility
       Syntax Guidelines.

       The following options shall be supported:

       -a     Write to standard output all the current settings for the terminal.

       -g     Write to standard output all the current settings in an unspecified form that can be used  as  arguments
              to  another invocation of the stty utility on the same system. The form used shall not contain any char-
              acters that would require quoting to avoid word expansion by the shell; see Word Expansions .


OPERANDS
       The following operands shall be supported to set the terminal characteristics.

   Control Modes
       parenb  (-parenb)
              Enable (disable) parity generation and detection. This shall have the effect of  setting  (not  setting)
              PARENB  in the termios c_cflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       parodd  (-parodd)

              Select odd (even) parity. This shall have the effect of setting (not  setting)  PARODD  in  the  termios
              c_cflag  field,  as  defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General
              Terminal Interface.

       cs5 cs6 cs7 cs8
              Select character size, if possible. This shall have the effect  of  setting  CS5,  CS6,  CS7,  and  CS8,
              respectively,   in   the   termios  c_cflag  field,  as  defined  in  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       number Set terminal baud rate to the number given, if possible. If the baud rate is set to zero, the modem con-
              trol  lines  shall  no  longer  be  asserted. This shall have the effect of setting the input and output
              termios baud rate values as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter  11,
              General Terminal Interface.

       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 shall be specified by the value of the output baud rate. This shall have the  effect
              of  setting  the  input  termios  baud  rate  values  as  defined  in  the  Base  Definitions  volume of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       ospeed  number
              Set terminal output baud rate to the number given, if possible. If the output baud rate is set to  zero,
              the  modem  control  lines shall no longer be asserted. This shall have the effect of setting the output
              termios baud rate values as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter  11,
              General Terminal Interface.

       hupcl  (-hupcl)
              Stop asserting modem control lines (do not stop asserting modem control lines) on last close. This shall
              have the effect of setting (not setting) HUPCL in the termios c_cflag field, as defined in the Base Def-
              initions volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       hup  (-hup)
              Equivalent to hupcl( -hupcl).

       cstopb  (-cstopb)
              Use two (one) stop bits per character. This shall have the effect of setting (not setting) CSTOPB in the
              termios c_cflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       cread  (-cread)
              Enable  (disable) the receiver. This shall have the effect of setting (not setting) CREAD in the termios
              c_cflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,  Chapter  11,  General
              Terminal Interface.

       clocal  (-clocal)
              Assume  a  line without (with) modem control. This shall have the effect of setting (not setting) CLOCAL
              in the termios c_cflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter
              11, General Terminal Interface.


       It is unspecified whether stty shall report an error if an attempt to set a Control Mode fails.

   Input Modes
       ignbrk  (-ignbrk)
              Ignore (do not ignore) break on input. This shall have the effect of setting (not setting) IGNBRK in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       brkint  (-brkint)
              Signal  (do not signal) INTR on break. This shall have the effect of setting (not setting) BRKINT in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       ignpar  (-ignpar)
              Ignore  (do  not  ignore)  bytes with parity errors. This shall have the effect of setting (not setting)
              IGNPAR in the termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       parmrk  (-parmrk)

              Mark  (do  not  mark)  parity  errors. This shall have the effect of setting (not setting) PARMRK in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       inpck  (-inpck)
              Enable (disable) input parity checking. This shall have the effect of setting (not setting) INPCK in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       istrip  (-istrip)
              Strip (do not strip) input characters to seven bits. This shall have the effect of setting (not setting)
              ISTRIP in the termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       inlcr  (-inlcr)
              Map  (do  not  map)  NL to CR on input. This shall have the effect of setting (not setting) INLCR in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       igncr (-igncr)
              Ignore  (do  not  ignore)  CR on input. This shall have the effect of setting (not setting) IGNCR in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       icrnl  (-icrnl)
              Map  (do  not  map)  CR to NL on input. This shall have the effect of setting (not setting) ICRNL in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       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. This shall have the effect  of  setting  (not  setting)
              IXON  in  the  termios c_iflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       ixany  (-ixany)
              Allow any character to restart output. This shall have the effect of setting (not setting) IXANY in  the
              termios  c_iflag  field,  as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11,
              General Terminal Interface.

       ixoff  (-ixoff)
              Request that the system send (not send) STOP characters when the input queue is nearly  full  and  START
              characters to resume data transmission. This shall have the effect of setting (not setting) IXOFF in the
              termios c_iflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.


   Output Modes
       opost  (-opost)
              Post-process  output  (do  not  post-process output; ignore all other output modes). This shall have the
              effect of setting (not setting) OPOST in the termios c_oflag field, as defined in the  Base  Definitions
              volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       ocrnl  (-ocrnl)
              Map  (do  not  map)  CR to NL on output This shall have the effect of setting (not setting) OCRNL in the
              termios c_oflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       onocr  (-onocr)
              Do  not  (do) output CR at column zero. This shall have the effect of setting (not setting) ONOCR in the
              termios c_oflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       onlret  (-onlret)
              The  terminal  newline  key  performs (does not perform) the CR function.  This shall have the effect of
              setting (not setting) ONLRET in the termios c_oflag field, as defined in the Base Definitions volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       ofill  (-ofill)
              Use  fill  characters (use timing) for delays. This shall have the effect of setting (not setting) OFILL
              in the termios c_oflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter
              11, General Terminal Interface.

       ofdel  (-ofdel)
              Fill  characters  are  DELs  (NULs).  This  shall  have the effect of setting (not setting) OFDEL in the
              termios c_oflag field, as defined in the Base Definitions volume of  IEEE Std 1003.1-2001,  Chapter  11,
              General Terminal Interface.

       cr0 cr1 cr2 cr3
              Select the style of delay for CRs. This shall have the effect of setting CRDLY to CR0, CR1, CR2, or CR3,
              respectively,  in  the  termios  c_oflag  field,  as  defined  in  the  Base   Definitions   volume   of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       nl0 nl1
              Select  the  style  of  delay for NL. This shall have the effect of setting NLDLY to NL0 or NL1, respec-
              tively, in the termios c_oflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       tab0 tab1 tab2 tab3

              Select  the  style  of  delay for horizontal tabs. This shall have the effect of setting TABDLY to TAB0,
              TAB1, TAB2, or TAB3, respectively, in the termios c_oflag field, as defined in the Base Definitions vol-
              ume  of  IEEE Std 1003.1-2001,  Chapter 11, General Terminal Interface. Note that TAB3 has the effect of
              expanding <tab>s to <space>s.

       tabs  (-tabs)
              Synonym for tab0 ( tab3).

       bs0 bs1
              Select the style of delay for backspaces. This shall have the effect of setting BSDLY  to  BS0  or  BS1,
              respectively,   in   the   termios  c_oflag  field,  as  defined  in  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       ff0 ff1
              Select the style of delay for form-feeds. This shall have the effect of setting FFDLY  to  FF0  or  FF1,
              respectively,   in   the   termios  c_oflag  field,  as  defined  in  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       vt0 vt1
              Select the style of delay for vertical-tabs. This shall have the effect of setting VTDLY to VT0 or  VT1,
              respectively,   in   the   termios  c_oflag  field,  as  defined  in  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.


   Local Modes
       isig  (-isig)
              Enable (disable) the checking of characters against the special control characters INTR, QUIT, and SUSP.
              This shall have the effect of setting (not setting) ISIG in the termios c_lflag field, as defined in the
              Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       icanon  (-icanon)
              Enable (disable) canonical input (ERASE and KILL processing). This shall have the effect of setting (not
              setting)  ICANON  in  the  termios  c_lflag  field,  as  defined  in  the  Base  Definitions  volume  of
              IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface.

       iexten  (-iexten)
              Enable (disable) any implementation-defined special  control  characters  not  currently  controlled  by
              icanon,  isig, ixon, or ixoff. This shall have the effect of setting (not setting) IEXTEN in the termios
              c_lflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,  Chapter  11,  General
              Terminal Interface.

       echo  (-echo)
              Echo  back (do not echo back) every character typed. This shall have the effect of setting (not setting)
              ECHO in the termios c_lflag field, as defined in the Base Definitions  volume  of  IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       echoe  (-echoe)
              The  ERASE  character  visually  erases (does not erase) the last character in the current line from the
              display, if possible. This shall have the effect of setting (not setting) ECHOE in the  termios  c_lflag
              field,  as  defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal
              Interface.

       echok  (-echok)
              Echo (do not echo) NL after KILL character. This shall have the effect of setting (not setting) ECHOK in
              the  termios  c_lflag  field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter
              11, General Terminal Interface.

       echonl  (-echonl)
              Echo (do not echo) NL, even if echo is disabled. This shall have the effect  of  setting  (not  setting)
              ECHONL  in the termios c_lflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       noflsh  (-noflsh)
              Disable (enable) flush after INTR, QUIT, SUSP. This shall have  the  effect  of  setting  (not  setting)
              NOFLSH  in the termios c_lflag field, as defined in the Base Definitions volume of IEEE Std 1003.1-2001,
              Chapter 11, General Terminal Interface.

       tostop  (-tostop)
              Send SIGTTOU for background output. This shall have the effect of setting (not setting)  TOSTOP  in  the
              termios  c_lflag  field,  as defined in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11,
              General Terminal Interface.


   Special Control Character Assignments
       <control>-character string

              Set <control>-character to string. If <control>-character is one of the character sequences in the first
              column  of the following table, the corresponding Base Definitions volume of IEEE Std 1003.1-2001, Chap-
              ter 11, General Terminal Interface control character from the second column shall  be  recognized.  This
              has  the effect of setting the corresponding element of the termios c_cc array (see the Base Definitions
              volume of IEEE Std 1003.1-2001, Chapter 13, Headers, <termios.h>).

                                               Table: Control Character Names in stty

                                         Control Character  c_cc Subscript  Description
                                         eof                VEOF            EOF character
                                         eol                VEOL            EOL character
                                         erase              VERASE          ERASE 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

       If string is a single character, the control character shall be set to that character. If string  is  the  two-
       character sequence "^-" or the string undef, the control character shall be set to _POSIX_VDISABLE, if it is in
       effect for the device; if _POSIX_VDISABLE is not in effect for the device, it shall be treated as an error.  In
       the POSIX locale, if string is a two-character sequence beginning with circumflex ( '^' ), and the second char-
       acter is one of those listed in the "^c" column of the following table, the control character shall be  set  to
       the corresponding character value in the Value column of the table.

                                        Table: Circumflex Control Characters in stty

                                         ^c     Value   ^c     Value   ^c     Value
                                         a, A   <SOH>   l, L   <FF>    w, W   <ETB>
                                         b, B   <STX>   m, M   <CR>    x, X   <CAN>
                                         c, C   <ETX>   n, N   <SO>    y, Y   <EM>
                                         d, D   <EOT>   o, O   <SI>    z, Z   <SUB>
                                         e, E   <ENQ>   p, P   <DLE>   [      <ESC>
                                         f, F   <ACK>   q, Q   <DC1>   \      <FS>
                                         g, G   <BEL>   r, R   <DC2>   ]      <GS>
                                         h, H   <BS>    s, S   <DC3>   ^      <RS>
                                         i, I   <HT>    t, T   <DC4> -------- <US>
                                         j, J   <LF>    u, U   <NAK>   ?      <DEL>
                                         k, K   <VT>    v, V   <SYN>

       min  number

              Set the value of MIN to number. MIN is used in non-canonical mode input processing ( icanon).

       time  number

              Set the value of TIME to number. TIME is 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, or -oddp

              Disable parenb, and set cs8.

       raw  (-raw or cooked)

              Enable (disable) raw input and output. Raw mode shall be equivalent to setting:


              stty cs8 erase ^- kill ^- intr ^- \
                  quit ^- eof ^- eol ^- -post -inpck

       nl  (-nl)

              Disable (enable) icrnl. In addition, -nl unsets inlcr and igncr.

       ek     Reset ERASE and KILL characters back to system defaults.

       sane

              Reset all modes to some reasonable, unspecified, values.


STDIN
       Although  no  input  is  read from standard input, standard input shall be used to get the current terminal I/O
       characteristics and to set new terminal I/O characteristics.

INPUT FILES
       None.

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of stty:

       LANG   Provide a default value for the internationalization variables that are unset or  null.  (See  the  Base
              Definitions  volume  of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the prece-
              dence of internationalization variables used to determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.

       LC_CTYPE
              This variable determines the locale for the interpretation of sequences of bytes of text data as charac-
              ters (for example, single-byte as opposed to multi-byte characters in arguments)  and  which  characters
              are in the class print.

       LC_MESSAGES
              Determine  the locale that should be used to affect the format and contents of diagnostic messages writ-
              ten to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .


ASYNCHRONOUS EVENTS
       Default.

STDOUT
       If operands are specified, no output shall be produced.

       If the -g option is specified, stty shall write to standard output the current settings in a form that  can  be
       used as arguments to another instance of stty on the same system.

       If  the -a option is specified, all of the information as described in the OPERANDS section shall be written to
       standard output. Unless otherwise specified, this information shall be written as <space>-separated  tokens  in
       an  unspecified format, on one or more lines, with an unspecified number of tokens per line.  Additional infor-
       mation may be written.

       If no options or operands are specified, an unspecified subset of the information written  for  the  -a  option
       shall be written.

       If speed information is written as part of the default output, or if the -a option is specified and if the ter-
       minal input speed and output speed are the same, the speed information shall be written as follows:


              "speed %d baud;", <speed>

       Otherwise, speeds shall be written as:


              "ispeed %d baud; ospeed %d baud;", <ispeed>, <ospeed>

       In locales other than the POSIX locale, the word baud may be changed to something  more  appropriate  in  those
       locales.

       If  control  characters  are  written  as part of the default output, or if the -a option is specified, control
       characters shall be written as:


              "%s = %s;", <control-character name>, <value>

       where <value> is either the character, or some visual representation of the character if it  is  non-printable,
       or the string undef if the character is disabled.

STDERR
       The standard error shall be used only for diagnostic messages.

OUTPUT FILES
       None.

EXTENDED DESCRIPTION
       None.

EXIT STATUS
       The following exit values shall be returned:

        0     The terminal options were read or set successfully.

       >0     An error occurred.


CONSEQUENCES OF ERRORS
       Default.

       The following sections are informative.

APPLICATION USAGE
       The  -g  flag  is  designed  to facilitate the saving and restoring of terminal state from the shell level. For
       example, a program may:


              saveterm="$(stty -g)"       # save terminal state
              stty (new settings)         # set new state
              ...                         # ...
              stty $saveterm              # restore terminal state

       Since the format is unspecified, the saved value is not portable across systems.

       Since the -a format is so loosely specified, scripts that save and restore terminal settings should use the  -g
       option.

EXAMPLES
       None.

RATIONALE
       The  original  stty  description  was  taken  directly from System V and reflected the System V terminal driver
       termio.  It has been modified to correspond to the terminal driver termios.

       Output modes are specified only for XSI-conformant systems. All implementations are expected  to  provide  stty
       operands corresponding to all of the output modes they support.

       The  stty  utility  is  primarily used to tailor the user interface of the terminal, such as selecting the pre-
       ferred ERASE and KILL characters. As an application programming utility, stty can be used within shell  scripts
       to alter the terminal settings for the duration of the script.

       The  termios  section  states  that  individual  disabling of control characters is possible through the option
       _POSIX_VDISABLE. If enabled, two conventions currently exist for specifying this: System V uses "^-",  and  BSD
       uses  undef.  Both  are  accepted  by stty in this volume of IEEE Std 1003.1-2001.  The other BSD convention of
       using the letter 'u' was rejected because it conflicts with the actual letter 'u', which is an acceptable value
       for a control character.

       Early  proposals  did not specify the mapping of "^c" to control characters because the control characters were
       not specified in the POSIX locale character set description file requirements.  The control  character  set  is
       now  specified in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 3, Definitions so the historical
       mapping is specified. Note that although the mapping corresponds to control-character key assignments  on  many
       terminals  that use the ISO/IEC 646:1991 standard (or ASCII) character encodings, the mapping specified here is
       to the control characters, not their keyboard encodings.

       Since termios supports separate speeds for input and output, two new options were added to  specify  each  dis-
       tinctly.

       Some historical implementations use standard input to get and set terminal characteristics; others use standard
       output. Since input from a login TTY is usually restricted to the owner while output to  a  TTY  is  frequently
       open  to anyone, using standard input provides fewer chances of accidentally (or maliciously) altering the ter-
       minal settings of other users. Using standard input also allows stty -a and stty -g output to be redirected for
       later use. Therefore, usage of standard input is required by this volume of IEEE Std 1003.1-2001.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Shell  Command  Language,  the  Base  Definitions  volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal
       Interface, <termios.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,  Inc  and  The
       Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Stan-
       dard, the original IEEE and The Open Group Standard is the referee  document.  The  original  Standard  can  be
       obtained online at http://www.opengroup.org/unix/online.html .



IEEE/The Open Group                  2003                             STTY(1P)