console_codes(4)                                      Kernel Interfaces Manual                                     console_codes(4)

       console_codes - Linux console escape and control sequences

       The  Linux  console  implements  a large subset of the VT102 and ECMA-48/ISO 6429/ANSI X3.64 terminal controls, plus certain
       private-mode sequences for changing the color palette, character-set mapping, and so on.  In the tabular descriptions below,
       the  second column gives ECMA-48 or DEC mnemonics (the latter if prefixed with DEC) for the given function.  Sequences with‐
       out a mnemonic are neither ECMA-48 nor VT102.

       After all the normal output processing has been done, and a stream of characters arrives at the console  driver  for  actual
       printing, the first thing that happens is a translation from the code used for processing to the code used for printing.

       If  the  console  is  in UTF-8 mode, then the incoming bytes are first assembled into 16-bit Unicode codes.  Otherwise, each
       byte is transformed according to the current mapping table (which translates it to a Unicode value).  See the Character Sets
       section below for discussion.

       In  the  normal case, the Unicode value is converted to a font index, and this is stored in video memory, so that the corre‐
       sponding glyph (as found in video ROM) appears on the screen.  Note that the use of Unicode (and the design of the PC  hard‐
       ware) allows us to use 512 different glyphs simultaneously.

       If  the  current  Unicode  value  is  a control character, or we are currently processing an escape sequence, the value will
       treated specially.  Instead of being turned into a font index and rendered as a glyph, it may  trigger  cursor  movement  or
       other control functions.  See the Linux Console Controls section below for discussion.

       It  is  generally  not good practice to hard-wire terminal controls into programs.  Linux supports a terminfo(5) database of
       terminal capabilities.  Rather than emitting console escape sequences by hand, you will almost always want  to  use  a  ter‐
       minfo-aware screen library or utility such as ncurses(3), tput(1), or reset(1).

   Linux console controls
       This  section  describes all the control characters and escape sequences that invoke special functions (i.e., anything other
       than writing a glyph at the current cursor location) on the Linux console.

       Control characters

       A character is a control character if (before transformation according to the mapping table) it has one of the 14  codes  00
       (NUL),  07  (BEL),  08 (BS), 09 (HT), 0a (LF), 0b (VT), 0c (FF), 0d (CR), 0e (SO), 0f (SI), 18 (CAN), 1a (SUB), 1b (ESC), 7f
       (DEL).  One can set a "display control characters" mode (see below), and allow 07, 09, 0b, 18, 1a, 7f  to  be  displayed  as
       glyphs.   On  the  other  hand, in UTF-8 mode all codes 00–1f are regarded as control characters, regardless of any "display
       control characters" mode.

       If we have a control character, it is acted upon immediately and then discarded (even in the middle of an  escape  sequence)
       and  the escape sequence continues with the next character.  (However, ESC starts a new escape sequence, possibly aborting a
       previous unfinished one, and CAN and SUB abort any escape sequence.)  The recognized control characters are BEL, BS, HT, LF,
       VT, FF, CR, SO, SI, CAN, SUB, ESC, DEL, CSI.  They do what one would expect:

       BEL (0x07, ^G)

       BS (0x08, ^H)
              backspaces one column (but not past the beginning of the line);

       HT (0x09, ^I)
              goes to the next tab stop or to the end of the line if there is no earlier tab stop;

       LF (0x0A, ^J)
       VT (0x0B, ^K)
       FF (0x0C, ^L)
              all give a linefeed, and if LF/NL (new-line mode) is set also a carriage return;

       CR (0x0D, ^M)
              gives a carriage return;

       SO (0x0E, ^N)
              activates the G1 character set;

       SI (0x0F, ^O)
              activates the G0 character set;

       CAN (0x18, ^X)
       SUB (0x1A, ^Z)
              abort escape sequences;

       ESC (0x1B, ^[)
              starts an escape sequence;

       DEL (0x7F)
              is ignored;

       CSI (0x9B)
              is equivalent to ESC [.

       ESC- but not CSI-sequences

       ESC c     RIS      Reset.
       ESC D     IND      Linefeed.
       ESC E     NEL      Newline.
       ESC H     HTS      Set tab stop at current column.
       ESC M     RI       Reverse linefeed.
       ESC Z     DECID    DEC private identification. The kernel returns the string  ESC [ ? 6 c, claiming that it is a VT102.
       ESC 7     DECSC    Save current state (cursor coordinates, attributes, character sets pointed at by G0, G1).
       ESC 8     DECRC    Restore state most recently saved by ESC 7.
       ESC %              Start sequence selecting character set
       ESC % @               Select default (ISO 646 / ISO 8859-1)
       ESC % G               Select UTF-8
       ESC % 8               Select UTF-8 (obsolete)
       ESC # 8   DECALN   DEC screen alignment test - fill screen with E's.
       ESC (              Start sequence defining G0 character set (followed by one of B, 0, U, K, as below)
       ESC ( B            Select default (ISO 8859-1 mapping).
       ESC ( 0            Select VT100 graphics mapping.
       ESC ( U            Select null mapping - straight to character ROM.
       ESC ( K            Select user mapping - the map that is loaded by the utility mapscrn(8).
       ESC )              Start sequence defining G1 (followed by one of B, 0, U, K, as above).
       ESC >     DECPNM   Set numeric keypad mode
       ESC =     DECPAM   Set application keypad mode
       ESC ]     OSC      Operating System Command prefix.
       ESC ] R            Reset palette.
       ESC ] P            Set palette, with parameter given in 7 hexadecimal digits nrrggbb after the final P. Here n is the color
                          (0–15), and rrggbb indicates the red/green/blue values (0–255).

       ECMA-48 CSI sequences

       CSI (or ESC [) is followed by a sequence of parameters, at most NPAR (16), that are decimal numbers separated by semicolons.
       An empty or absent parameter is taken to be 0.  The sequence of parameters may be preceded by a single question mark.

       However, after CSI [ (or ESC [ [) a single character is read and this entire sequence is ignored.  (The idea is to ignore an
       echoed function key.)

       The action of a CSI sequence is determined by its final character.

       @   ICH       Insert the indicated # of blank characters.
       A   CUU       Move cursor up the indicated # of rows.
       B   CUD       Move cursor down the indicated # of rows.
       C   CUF       Move cursor right the indicated # of columns.
       D   CUB       Move cursor left the indicated # of columns.
       E   CNL       Move cursor down the indicated # of rows, to column 1.
       F   CPL       Move cursor up the indicated # of rows, to column 1.
       G   CHA       Move cursor to indicated column in current row.

       H   CUP       Move cursor to the indicated row, column (origin at 1,1).
       J   ED        Erase display (default: from cursor to end of display).
                     ESC [ 1 J: erase from start to cursor.
                     ESC [ 2 J: erase whole display.
                     ESC [ 3 J: erase whole display including scroll-back buffer (since Linux 3.0).
       K   EL        Erase line (default: from cursor to end of line).
                     ESC [ 1 K: erase from start of line to cursor.
                     ESC [ 2 K: erase whole line.
       L   IL        Insert the indicated # of blank lines.
       M   DL        Delete the indicated # of lines.
       P   DCH       Delete the indicated # of characters on current line.
       X   ECH       Erase the indicated # of characters on current line.
       a   HPR       Move cursor right the indicated # of columns.
       c   DA        Answer ESC [ ? 6 c: "I am a VT102".
       d   VPA       Move cursor to the indicated row, current column.
       e   VPR       Move cursor down the indicated # of rows.
       f   HVP       Move cursor to the indicated row, column.
       g   TBC       Without parameter: clear tab stop at current position.
                     ESC [ 3 g: delete all tab stops.
       h   SM        Set Mode (see below).
       l   RM        Reset Mode (see below).
       m   SGR       Set attributes (see below).
       n   DSR       Status report (see below).
       q   DECLL     Set keyboard LEDs.
                     ESC [ 0 q: clear all LEDs
                     ESC [ 1 q: set Scroll Lock LED
                     ESC [ 2 q: set Num Lock LED
                     ESC [ 3 q: set Caps Lock LED
       r   DECSTBM   Set scrolling region; parameters are top and bottom row.
       s   ?         Save cursor location.
       u   ?         Restore cursor location.
       `   HPA       Move cursor to indicated column in current row.

       ECMA-48 Select Graphic Rendition

       The ECMA-48 SGR sequence ESC [ parameters m sets display attributes.  Several attributes can be set in  the  same  sequence,
       separated  by  semicolons.   An  empty  parameter (between semicolons or string initiator or terminator) is interpreted as a

       param      result
       0          reset all attributes to their defaults
       1          set bold
       2          set half-bright (simulated with color on a color display)
       3          set italic (since Linux 2.6.22; simulated with color on a color display)
       4          set underscore (simulated with color on a color display) (the colors used to simulate dim or underline are set
                  using ESC ] ...)
       5          set blink
       7          set reverse video
       10         reset selected mapping, display control flag, and toggle meta flag (ECMA-48 says "primary font").
       11         select null mapping, set display control flag, reset toggle meta flag (ECMA-48 says "first alternate font").
       12         select null mapping, set display control flag, set toggle meta flag (ECMA-48 says "second alternate font").  The
                  toggle meta flag causes the high bit of a byte to be toggled before the mapping table translation is done.
       21         set underline; before Linux 4.17, this value set normal intensity (as is done in many other terminals)
       22         set normal intensity
       23         italic off (since Linux 2.6.22)
       24         underline off
       25         blink off
       27         reverse video off
       30         set black foreground
       31         set red foreground
       32         set green foreground
       33         set brown foreground
       34         set blue foreground
       35         set magenta foreground
       36         set cyan foreground

       37         set white foreground
       38         256/24-bit foreground color follows, shoehorned into 16 basic colors (before Linux 3.16: set underscore on, set
                  default foreground color)
       39         set default foreground color (before Linux 3.16: set underscore off, set default foreground color)
       40         set black background
       41         set red background
       42         set green background
       43         set brown background
       44         set blue background
       45         set magenta background
       46         set cyan background
       47         set white background
       48         256/24-bit background color follows, shoehorned into 8 basic colors
       49         set default background color
       90..97     set foreground to bright versions of 30..37
       100..107   set background, same as 40..47 (bright not supported)

       Commands 38 and 48 require further arguments:

       ;5;x       256 color: values 0..15 are IBGR (black, red, green, ... white), 16..231 a 6x6x6 color cube, 232..255 a grayscale
       ;2;r;g;b   24-bit color, r/g/b components are in the range 0..255

       ECMA-48 Mode Switches

       ESC [ 3 h
              DECCRM (default off): Display control chars.

       ESC [ 4 h
              DECIM (default off): Set insert mode.

       ESC [ 20 h
              LF/NL (default off): Automatically follow echo of LF, VT, or FF with CR.

       ECMA-48 Status Report Commands

       ESC [ 5 n
              Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).

       ESC [ 6 n
              Cursor position report (CPR): Answer is ESC [ y ; x R, where x,y is the cursor location.

       DEC Private Mode (DECSET/DECRST) sequences

       These are not described in ECMA-48.  We list the Set Mode sequences; the Reset Mode sequences are obtained by replacing  the
       final 'h' by 'l'.

       ESC [ ? 1 h
              DECCKM (default off): When set, the cursor keys send an ESC O prefix, rather than ESC [.

       ESC [ ? 3 h
              DECCOLM  (default  off  = 80 columns): 80/132 col mode switch.  The driver sources note that this alone does not suf‐
              fice; some user-mode utility such as resizecons(8) has to change the hardware registers on the console video card.

       ESC [ ? 5 h
              DECSCNM (default off): Set reverse-video mode.

       ESC [ ? 6 h
              DECOM (default off): When set, cursor addressing is relative to the upper left corner of the scrolling region.

       ESC [ ? 7 h
              DECAWM (default on): Set autowrap on.  In this mode, a graphic character emitted after column 80 (or  column  132  of
              DECCOLM is on) forces a wrap to the beginning of the following line first.

       ESC [ ? 8 h
              DECARM (default on): Set keyboard autorepeat on.

       ESC [ ? 9 h
              X10 Mouse Reporting (default off): Set reporting mode to 1 (or reset to 0)—see below.

       ESC [ ? 25 h
              DECTECM (default on): Make cursor visible.

       ESC [ ? 1000 h
              X11 Mouse Reporting (default off): Set reporting mode to 2 (or reset to 0)—see below.

       Linux Console Private CSI Sequences

       The  following  sequences are neither ECMA-48 nor native VT102.  They are native to the Linux console driver.  Colors are in
       SGR parameters: 0 = black, 1 = red, 2 = green, 3 = brown, 4 = blue, 5 = magenta, 6 = cyan, 7 = white; 8–15 = bright versions
       of 0–7.

       ESC [ 1 ; n ]       Set color n as the underline color.
       ESC [ 2 ; n ]       Set color n as the dim color.
       ESC [ 8 ]           Make the current color pair the default attributes.
       ESC [ 9 ; n ]       Set screen blank timeout to n minutes.
       ESC [ 10 ; n ]      Set bell frequency in Hz.
       ESC [ 11 ; n ]      Set bell duration in msec.
       ESC [ 12 ; n ]      Bring specified console to the front.
       ESC [ 13 ]          Unblank the screen.
       ESC [ 14 ; n ]      Set the VESA powerdown interval in minutes.
       ESC [ 15 ]          Bring the previous console to the front (since Linux 2.6.0).
       ESC [ 16 ; n ]      Set the cursor blink interval in milliseconds (since Linux 4.2).

   Character sets
       The  kernel knows about 4 translations of bytes into console-screen symbols.  The four tables are: a) Latin1 -> PC, b) VT100
       graphics -> PC, c) PC -> PC, d) user-defined.

       There are two character sets, called G0 and G1, and one of them is the current character set.  (Initially  G0.)   Typing  ^N
       causes G1 to become current, ^O causes G0 to become current.

       These  variables  G0 and G1 point at a translation table, and can be changed by the user.  Initially they point at tables a)
       and b), respectively.  The sequences ESC ( B and ESC ( 0 and ESC ( U and ESC ( K cause G0 to point at translation table  a),
       b),  c),  and  d), respectively.  The sequences ESC ) B and ESC ) 0 and ESC ) U and ESC ) K cause G1 to point at translation
       table a), b), c), and d), respectively.

       The sequence ESC c causes a terminal reset, which is what you want if the screen is  all  garbled.   The  oft-advised  "echo
       ^V^O"  will  make  only  G0 current, but there is no guarantee that G0 points at table a).  In some distributions there is a
       program reset(1) that just does "echo ^[c".  If your terminfo entry for the console is correct (and has an  entry  rs1=\Ec),
       then "tput reset" will also work.

       The user-defined mapping table can be set using mapscrn(8).  The result of the mapping is that if a symbol c is printed, the
       symbol s = map[c] is sent to the video memory.  The bitmap that corresponds to s is found in the character ROM, and  can  be
       changed using setfont(8).

   Mouse tracking
       The  mouse tracking facility is intended to return xterm(1)-compatible mouse status reports.  Because the console driver has
       no way to know the device or type of the mouse, these reports are returned in the console input stream only when the virtual
       terminal  driver  receives a mouse update ioctl.  These ioctls must be generated by a mouse-aware user-mode application such
       as the gpm(8) daemon.

       The mouse tracking escape sequences generated by xterm(1) encode numeric parameters in a single character as value+040.  For
       example, '!' is 1.  The screen coordinate system is 1-based.

       The  X10 compatibility mode sends an escape sequence on button press encoding the location and the mouse button pressed.  It
       is enabled by sending ESC [ ? 9 h and disabled with ESC [ ? 9 l.  On button press, xterm(1) sends ESC [  M  bxy  (6  charac‐
       ters).   Here  b is button-1, and x and y are the x and y coordinates of the mouse when the button was pressed.  This is the
       same code the kernel also produces.

       Normal tracking mode (not implemented in Linux 2.0.24) sends an escape sequence on both button press and release.   Modifier
       information is also sent.  It is enabled by sending ESC [ ? 1000 h and disabled with ESC [ ? 1000 l.  On button press or re‐
       lease, xterm(1) sends ESC [ M bxy.  The low two bits of b encode button information: 0=MB1  pressed,  1=MB2  pressed,  2=MB3
       pressed,  3=release.   The  upper  bits  encode what modifiers were down when the button was pressed and are added together:
       4=Shift, 8=Meta, 16=Control.  Again x and y are the x and y coordinates of the mouse event.  The upper left corner is (1,1).

   Comparisons with other terminals
       Many different terminal types are described, like the Linux console, as being "VT100-compatible".  Here we  discuss  differ‐
       ences between the Linux console and the two most important others, the DEC VT102 and xterm(1).

       Control-character handling

       The VT102 also recognized the following control characters:

       NUL (0x00)
              was ignored;

       ENQ (0x05)
              triggered an answerback message;

       DC1 (0x11, ^Q, XON)
              resumed transmission;

       DC3 (0x13, ^S, XOFF)
              caused VT100 to ignore (and stop transmitting) all codes except XOFF and XON.

       VT100-like DC1/DC3 processing may be enabled by the terminal driver.

       The xterm(1) program (in VT100 mode) recognizes the control characters BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.

       Escape sequences

       VT100 console sequences not implemented on the Linux console:

       ESC N       SS2   Single  shift 2. (Select G2 char‐
                         acter set for the next  character
       ESC O       SS3   Single  shift 3. (Select G3 char‐
                         acter set for the next  character
       ESC P       DCS   Device  control  string (ended by
                         ESC \)
       ESC X       SOS   Start of string.
       ESC ^       PM    Privacy message (ended by ESC \)
       ESC \       ST    String terminator
       ESC * ...         Designate G2 character set
       ESC + ...         Designate G3 character set

       The program xterm(1) (in VT100 mode) recognizes ESC c, ESC # 8, ESC >, ESC =, ESC D, ESC E, ESC H, ESC M, ESC N, ESC O,  ESC
       P ... ESC \, ESC Z (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with advanced video option") and ESC ^ ... ESC \ with the same
       meanings as indicated above.  It accepts ESC (, ESC ), ESC *,  ESC + followed by 0, A, B for the DEC special  character  and
       line drawing set, UK, and US-ASCII, respectively.

       The  user  can  configure  xterm(1)  to  respond to VT220-specific control sequences, and it will identify itself as a VT52,
       VT100, and up depending on the way it is configured and initialized.

       It accepts ESC ] (OSC) for the setting of certain resources.  In addition to the ECMA-48 string  terminator  (ST),  xterm(1)
       accepts a BEL to terminate an OSC string.  These are a few of the OSC control sequences recognized by xterm(1):

       ESC ] 0 ; txt ST        Set icon name and window title to txt.
       ESC ] 1 ; txt ST        Set icon name to txt.
       ESC ] 2 ; txt ST        Set window title to txt.
       ESC ] 4 ; num; txt ST   Set ANSI color num to txt.
       ESC ] 10 ; txt ST       Set dynamic text color to txt.
       ESC ] 4 6 ; name ST     Change  log  file to name (normally disabled
                               by a compile-time option).
       ESC ] 5 0 ; fn ST       Set font to fn.

       It recognizes the following with slightly modified meaning (saving more state, behaving closer to VT100/VT220):

       ESC 7  DECSC   Save cursor

       ESC 8  DECRC   Restore cursor

       It also recognizes

       ESC F          Cursor to lower left corner of screen (if enabled by xterm(1)'s hpLowerleftBugCompat resource).
       ESC l          Memory lock (per HP terminals).
                      Locks memory above the cursor.
       ESC m          Memory unlock (per HP terminals).
       ESC n   LS2    Invoke the G2 character set.
       ESC o   LS3    Invoke the G3 character set.
       ESC |   LS3R   Invoke the G3 character set as GR.
                      Has no visible effect in xterm.
       ESC }   LS2R   Invoke the G2 character set as GR.
                      Has no visible effect in xterm.
       ESC ~   LS1R   Invoke the G1 character set as GR.

       It also recognizes ESC % and provides a more complete UTF-8 implementation than Linux console.

       CSI Sequences

       Old versions of xterm(1), for example, from X11R5, interpret the blink SGR as a bold SGR.  Later versions which  implemented
       ANSI  colors, for example, XFree86 3.1.2A in 1995, improved this by allowing the blink attribute to be displayed as a color.
       Modern versions of xterm implement blink SGR as blinking text and still allow colored text  as  an  alternate  rendering  of
       SGRs.   Stock  X11R6 versions did not recognize the color-setting SGRs until the X11R6.8 release, which incorporated XFree86
       xterm.  All ECMA-48 CSI sequences recognized by Linux are also recognized by  xterm,  however  xterm(1)  implements  several
       ECMA-48 and DEC control sequences not recognized by Linux.

       The  xterm(1)  program recognizes all of the DEC Private Mode sequences listed above, but none of the Linux private-mode se‐
       quences.  For discussion of xterm(1)'s own private-mode sequences, refer to the Xterm Control Sequences document  by  Edward
       Moy,  Stephen  Gildea,  and Thomas E. Dickey available with the X distribution.  That document, though terse, is much longer
       than this manual page.  For a chronological overview,


       details changes to xterm.

       The vttest program


       demonstrates many of these control sequences.  The xterm(1) source distribution also contains sample scripts which  exercise
       other features.

       ESC 8 (DECRC) is not able to restore the character set changed with ESC %.

       In Linux 2.0.23, CSI is broken, and NUL is not ignored inside escape sequences.

       Some  older  kernel versions (after Linux 2.0) interpret 8-bit control sequences.  These "C1 controls" use codes between 128
       and 159 to replace ESC [, ESC ] and similar two-byte control sequence initiators.  There are fragments  of  that  in  modern
       kernels  (either  overlooked  or broken by changes to support UTF-8), but the implementation is incomplete and should be re‐
       garded as unreliable.

       Linux "private mode" sequences do not follow the rules in ECMA-48 for private mode control sequences.  In particular,  those
       ending  with  ]  do  not  use  a standard terminating character.  The OSC (set palette) sequence is a greater problem, since
       xterm(1) may interpret this as a control sequence which requires a string terminator (ST).  Unlike the setterm(1)  sequences
       which  will  be  ignored  (since they are invalid control sequences), the palette sequence will make xterm(1) appear to hang
       (though pressing the return-key will fix that).  To accommodate applications which have been hardcoded to use Linux  control
       sequences, set the xterm(1) resource brokenLinuxOSC to true.

       An  older version of this document implied that Linux recognizes the ECMA-48 control sequence for invisible text.  It is ig‐

       ioctl_console(2), charsets(7)

Linux man-pages 6.03                                         2023-02-05                                            console_codes(4)