1CONSOLE_CODES(4) Linux Programmer's Manual CONSOLE_CODES(4)
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6 console_codes - Linux console escape and control sequences
7
9 The Linux console implements a large subset of the VT102 and
10 ECMA-48/ISO 6429/ANSI X3.64 terminal controls, plus certain private-
11 mode sequences for changing the color palette, character-set mapping,
12 and so on. In the tabular descriptions below, the second column gives
13 ECMA-48 or DEC mnemonics (the latter if prefixed with DEC) for the
14 given function. Sequences without a mnemonic are neither ECMA-48 nor
15 VT102.
16 After all the normal output processing has been done, and a stream of
18 characters arrives at the console driver for actual printing, the first
19 thing that happens is a translation from the code used for processing
20 to the code used for printing.
21 If the console is in UTF-8 mode, then the incoming bytes are first
23 assembled into 16-bit Unicode codes. Otherwise, each byte is trans‐
24 formed according to the current mapping table (which translates it to a
25 Unicode value). See the Character Sets section below for discussion.
26 In the normal case, the Unicode value is converted to a font index, and
28 this is stored in video memory, so that the corresponding glyph (as
29 found in video ROM) appears on the screen. Note that the use of Uni‐
30 code (and the design of the PC hardware) allows us to use 512 different
31 glyphs simultaneously.
32 If the current Unicode value is a control character, or we are cur‐
34 rently processing an escape sequence, the value will treated specially.
35 Instead of being turned into a font index and rendered as a glyph, it
36 may trigger cursor movement or other control functions. See the Linux
37 Console Controls section below for discussion.
38 It is generally not good practice to hard-wire terminal controls into
40 programs. Linux supports a terminfo(5) database of terminal capabili‐
41 ties. Rather than emitting console escape sequences by hand, you will
42 almost always want to use a terminfo-aware screen library or utility
43 such as ncurses(3), tput(1), or reset(1).
44 Linux console controls
46 This section describes all the control characters and escape sequences
47 that invoke special functions (i.e., anything other than writing a
48 glyph at the current cursor location) on the Linux console.
49 Control characters
51 A character is a control character if (before transformation according
53 to the mapping table) it has one of the 14 codes 00 (NUL), 07 (BEL), 08
54 (BS), 09 (HT), 0a (LF), 0b (VT), 0c (FF), 0d (CR), 0e (SO), 0f (SI), 18
55 (CAN), 1a (SUB), 1b (ESC), 7f (DEL). One can set a "display control
56 characters" mode (see below), and allow 07, 09, 0b, 18, 1a, 7f to be
57 displayed as glyphs. On the other hand, in UTF-8 mode all codes 00–1f
58 are regarded as control characters, regardless of any "display control
59 characters" mode.
60 If we have a control character, it is acted upon immediately and then
62 discarded (even in the middle of an escape sequence) and the escape
63 sequence continues with the next character. (However, ESC starts a new
64 escape sequence, possibly aborting a previous unfinished one, and CAN
65 and SUB abort any escape sequence.) The recognized control characters
66 are BEL, BS, HT, LF, VT, FF, CR, SO, SI, CAN, SUB, ESC, DEL, CSI. They
67 do what one would expect:
68 BEL (0x07, ^G) beeps;
70 BS (0x08, ^H) backspaces one column (but not past the beginning of the
72 line);
73 HT (0x09, ^I) goes to the next tab stop or to the end of the line if
75 there is no earlier tab stop;
76 LF (0x0A, ^J), VT (0x0B, ^K) and FF (0x0C, ^L) all give a linefeed, and
78 if LF/NL (new-line mode) is set also a carriage return;
79 CR (0x0D, ^M) gives a carriage return;
81 SO (0x0E, ^N) activates the G1 character set;
83 SI (0x0F, ^O) activates the G0 character set;
85 CAN (0x18, ^X) and SUB (0x1A, ^Z) abort escape sequences;
87 ESC (0x1B, ^[) starts an escape sequence;
89 DEL (0x7F) is ignored;
91 CSI (0x9B) is equivalent to ESC [.
93 ESC- but not CSI-sequences
95 ESC c RIS Reset.
97 ESC D IND Linefeed.
98 ESC E NEL Newline.
99 ESC H HTS Set tab stop at current column.
100 ESC M RI Reverse linefeed.
101 ESC Z DECID DEC private identification. The kernel returns the
102 string ESC [ ? 6 c, claiming that it is a VT102.
103 ESC 7 DECSC Save current state (cursor coordinates,
104 attributes, character sets pointed at by G0, G1).
105 ESC 8 DECRC Restore state most recently saved by ESC 7.
106 ESC [ CSI Control sequence introducer
107 ESC % Start sequence selecting character set
108 ESC % @ Select default (ISO 646 / ISO 8859-1)
109 ESC % G Select UTF-8
110 ESC % 8 Select UTF-8 (obsolete)
111 ESC # 8 DECALN DEC screen alignment test - fill screen with E's.
112 ESC ( Start sequence defining G0 character set
113 ESC ( B Select default (ISO 8859-1 mapping)
114 ESC ( 0 Select VT100 graphics mapping
115 ESC ( U Select null mapping - straight to character ROM
116 ESC ( K Select user mapping - the map that is loaded by
117 the utility mapscrn(8).
118 ESC ) Start sequence defining G1
119 (followed by one of B, 0, U, K, as above).
120 ESC > DECPNM Set numeric keypad mode
121 ESC = DECPAM Set application keypad mode
122 ESC ] OSC (Should be: Operating system command) ESC ] P
123 nrrggbb: set palette, with parameter given in 7
124 hexadecimal digits after the final P :-(. Here n
125 is the color (0–15), and rrggbb indicates the
126 red/green/blue values (0–255). ESC ] R: reset
127 palette
128 ECMA-48 CSI sequences
130 CSI (or ESC [) is followed by a sequence of parameters, at most NPAR
132 (16), that are decimal numbers separated by semicolons. An empty or
133 absent parameter is taken to be 0. The sequence of parameters may be
134 preceded by a single question mark.
135 However, after CSI [ (or ESC [ [) a single character is read and this
137 entire sequence is ignored. (The idea is to ignore an echoed function
138 key.)
139 The action of a CSI sequence is determined by its final character.
141 @ ICH Insert the indicated # of blank characters.
143 A CUU Move cursor up the indicated # of rows.
144 B CUD Move cursor down the indicated # of rows.
145 C CUF Move cursor right the indicated # of columns.
146 D CUB Move cursor left the indicated # of columns.
147 E CNL Move cursor down the indicated # of rows, to column 1.
148 F CPL Move cursor up the indicated # of rows, to column 1.
149 G CHA Move cursor to indicated column in current row.
150 H CUP Move cursor to the indicated row, column (origin at 1,1).
151 J ED Erase display (default: from cursor to end of display).
152 ESC [ 1 J: erase from start to cursor.
153 ESC [ 2 J: erase whole display.
154 ESC [ 3 J: erase whole display including scroll-back
155 buffer (since Linux 3.0).
156 K EL Erase line (default: from cursor to end of line).
157 ESC [ 1 K: erase from start of line to cursor.
158 ESC [ 2 K: erase whole line.
159 L IL Insert the indicated # of blank lines.
160 M DL Delete the indicated # of lines.
161 P DCH Delete the indicated # of characters on current line.
162 X ECH Erase the indicated # of characters on current line.
163 a HPR Move cursor right the indicated # of columns.
164 c DA Answer ESC [ ? 6 c: "I am a VT102".
165 d VPA Move cursor to the indicated row, current column.
166 e VPR Move cursor down the indicated # of rows.
167 f HVP Move cursor to the indicated row, column.
168 g TBC Without parameter: clear tab stop at current position.
169 ESC [ 3 g: delete all tab stops.
170 h SM Set Mode (see below).
171 l RM Reset Mode (see below).
172 m SGR Set attributes (see below).
173 n DSR Status report (see below).
174 q DECLL Set keyboard LEDs.
175 ESC [ 0 q: clear all LEDs
176 ESC [ 1 q: set Scroll Lock LED
177 ESC [ 2 q: set Num Lock LED
178 ESC [ 3 q: set Caps Lock LED
179 r DECSTBM Set scrolling region; parameters are top and bottom row.
180 s ? Save cursor location.
181 u ? Restore cursor location.
182 ` HPA Move cursor to indicated column in current row.
183 ECMA-48 Set Graphics Rendition
185 The ECMA-48 SGR sequence ESC [ parameters m sets display attributes.
187 Several attributes can be set in the same sequence, separated by semi‐
188 colons. An empty parameter (between semicolons or string initiator or
189 terminator) is interpreted as a zero.
190 param result
192 0 reset all attributes to their defaults
193 1 set bold
194 2 set half-bright (simulated with color on a color display)
195 4 set underscore (simulated with color on a color display)
196 (the colors used to simulate dim or underline are set
197 using ESC ] ...)
198 5 set blink
200 7 set reverse video
201 10 reset selected mapping, display control flag, and toggle
202 meta flag (ECMA-48 says "primary font").
203 11 select null mapping, set display control flag, reset tog‐
204 gle meta flag (ECMA-48 says "first alternate font").
205 12 select null mapping, set display control flag, set toggle
206 meta flag (ECMA-48 says "second alternate font"). The
207 toggle meta flag causes the high bit of a byte to be tog‐
208 gled before the mapping table translation is done.
209 21 set underline; before Linux 4.17, this value set normal
210 intensity (as is done in many other terminals)
211 22 set normal intensity
212 24 underline off
213 25 blink off
214 27 reverse video off
215 30 set black foreground
216 31 set red foreground
217 32 set green foreground
218 33 set brown foreground
219 34 set blue foreground
220 35 set magenta foreground
221 36 set cyan foreground
222 37 set white foreground
223 38 256/24-bit foreground color follows, shoehorned into 16
224 basic colors (before Linux 3.16: set underscore on, set
225 default foreground color)
226 39 set default foreground color (before Linux 3.16: set
227 underscore off, set default foreground color)
228 40 set black background
229 41 set red background
230 42 set green background
231 43 set brown background
232 44 set blue background
233 45 set magenta background
234 46 set cyan background
235 47 set white background
236 48 256/24-bit background color follows, shoehorned into 8
237 basic colors
238 49 set default background color
239 90..97 set foreground to bright versions of 30..37
240 100.107 set background, same as 40..47 (bright not supported)
241 Commands 38 and 48 require further arguments:
243 ;5;x 256 color: values 0..15 are IBGR (black, red, green,
245 ... white), 16..231 a 6x6x6 color cube, 232..255 a
246 grayscale ramp
247 ;2;r;g;b 24-bit color, r/g/b components are in the range 0..255
248 ECMA-48 Mode Switches
250 ESC [ 3 h
252 DECCRM (default off): Display control chars.
253 ESC [ 4 h
255 DECIM (default off): Set insert mode.
256 ESC [ 20 h
258 LF/NL (default off): Automatically follow echo of LF, VT or FF
259 with CR.
260 ECMA-48 Status Report Commands
262 ESC [ 5 n
264 Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).
265 ESC [ 6 n
267 Cursor position report (CPR): Answer is ESC [ y ; x R, where x,y
268 is the cursor location.
269 DEC Private Mode (DECSET/DECRST) sequences
271 These are not described in ECMA-48. We list the Set Mode sequences;
273 the Reset Mode sequences are obtained by replacing the final 'h' by
274 'l'.
275 ESC [ ? 1 h
277 DECCKM (default off): When set, the cursor keys send an ESC O
278 prefix, rather than ESC [.
279 ESC [ ? 3 h
281 DECCOLM (default off = 80 columns): 80/132 col mode switch. The
282 driver sources note that this alone does not suffice; some user-
283 mode utility such as resizecons(8) has to change the hardware
284 registers on the console video card.
285 ESC [ ? 5 h
287 DECSCNM (default off): Set reverse-video mode.
288 ESC [ ? 6 h
290 DECOM (default off): When set, cursor addressing is relative to
291 the upper left corner of the scrolling region.
292 ESC [ ? 7 h
294 DECAWM (default on): Set autowrap on. In this mode, a graphic
295 character emitted after column 80 (or column 132 of DECCOLM is
296 on) forces a wrap to the beginning of the following line first.
297 ESC [ ? 8 h
299 DECARM (default on): Set keyboard autorepeat on.
300 ESC [ ? 9 h
302 X10 Mouse Reporting (default off): Set reporting mode to 1 (or
303 reset to 0)—see below.
304 ESC [ ? 25 h
306 DECTECM (default on): Make cursor visible.
307 ESC [ ? 1000 h
309 X11 Mouse Reporting (default off): Set reporting mode to 2 (or
310 reset to 0)—see below.
311 Linux Console Private CSI Sequences
313 The following sequences are neither ECMA-48 nor native VT102. They are
315 native to the Linux console driver. Colors are in SGR parameters: 0 =
316 black, 1 = red, 2 = green, 3 = brown, 4 = blue, 5 = magenta, 6 = cyan,
317 7 = white; 8–15 = bright versions of 0–7.
318 ESC [ 1 ; n ] Set color n as the underline color.
320 ESC [ 2 ; n ] Set color n as the dim color.
321 ESC [ 8 ] Make the current color pair the default attributes.
322 ESC [ 9 ; n ] Set screen blank timeout to n minutes.
323 ESC [ 10 ; n ] Set bell frequency in Hz.
324 ESC [ 11 ; n ] Set bell duration in msec.
325 ESC [ 12 ; n ] Bring specified console to the front.
326 ESC [ 13 ] Unblank the screen.
327 ESC [ 14 ; n ] Set the VESA powerdown interval in minutes.
328 ESC [ 15 ] Bring the previous console to the front (since
329 Linux 2.6.0).
330 ESC [ 16 ; n ] Set the cursor blink interval in milliseconds
331 (since Linux 4.2).
332 Character sets
334 The kernel knows about 4 translations of bytes into console-screen sym‐
335 bols. The four tables are: a) Latin1 -> PC, b) VT100 graphics -> PC,
336 c) PC -> PC, d) user-defined.
337 There are two character sets, called G0 and G1, and one of them is the
339 current character set. (Initially G0.) Typing ^N causes G1 to become
340 current, ^O causes G0 to become current.
341 These variables G0 and G1 point at a translation table, and can be
343 changed by the user. Initially they point at tables a) and b), respec‐
344 tively. The sequences ESC ( B and ESC ( 0 and ESC ( U and ESC ( K
345 cause G0 to point at translation table a), b), c) and d), respectively.
346 The sequences ESC ) B and ESC ) 0 and ESC ) U and ESC ) K cause G1 to
347 point at translation table a), b), c) and d), respectively.
348 The sequence ESC c causes a terminal reset, which is what you want if
350 the screen is all garbled. The oft-advised "echo ^V^O" will make only
351 G0 current, but there is no guarantee that G0 points at table a). In
352 some distributions there is a program reset(1) that just does "echo
353 ^[c". If your terminfo entry for the console is correct (and has an
354 entry rs1=\Ec), then "tput reset" will also work.
355 The user-defined mapping table can be set using mapscrn(8). The result
357 of the mapping is that if a symbol c is printed, the symbol s = map[c]
358 is sent to the video memory. The bitmap that corresponds to s is found
359 in the character ROM, and can be changed using setfont(8).
360 Mouse tracking
362 The mouse tracking facility is intended to return xterm(1)-compatible
363 mouse status reports. Because the console driver has no way to know
364 the device or type of the mouse, these reports are returned in the con‐
365 sole input stream only when the virtual terminal driver receives a
366 mouse update ioctl. These ioctls must be generated by a mouse-aware
367 user-mode application such as the gpm(8) daemon.
368 The mouse tracking escape sequences generated by xterm(1) encode
370 numeric parameters in a single character as value+040. For example,
371 '!' is 1. The screen coordinate system is 1-based.
372 The X10 compatibility mode sends an escape sequence on button press
374 encoding the location and the mouse button pressed. It is enabled by
375 sending ESC [ ? 9 h and disabled with ESC [ ? 9 l. On button press,
376 xterm(1) sends ESC [ M bxy (6 characters). Here b is button-1, and x
377 and y are the x and y coordinates of the mouse when the button was
378 pressed. This is the same code the kernel also produces.
379 Normal tracking mode (not implemented in Linux 2.0.24) sends an escape
381 sequence on both button press and release. Modifier information is
382 also sent. It is enabled by sending ESC [ ? 1000 h and disabled with
383 ESC [ ? 1000 l. On button press or release, xterm(1) sends ESC [ M
384 bxy. The low two bits of b encode button information: 0=MB1 pressed,
385 1=MB2 pressed, 2=MB3 pressed, 3=release. The upper bits encode what
386 modifiers were down when the button was pressed and are added together:
387 4=Shift, 8=Meta, 16=Control. Again x and y are the x and y coordinates
388 of the mouse event. The upper left corner is (1,1).
389 Comparisons with other terminals
391 Many different terminal types are described, like the Linux console, as
392 being "VT100-compatible". Here we discuss differences between the
393 Linux console and the two most important others, the DEC VT102 and
394 xterm(1).
395 Control-character handling
397 The VT102 also recognized the following control characters:
399 NUL (0x00) was ignored;
401 ENQ (0x05) triggered an answerback message;
403 DC1 (0x11, ^Q, XON) resumed transmission;
405 DC3 (0x13, ^S, XOFF) caused VT100 to ignore (and stop transmitting) all
407 codes except XOFF and XON.
408 VT100-like DC1/DC3 processing may be enabled by the terminal driver.
410 The xterm(1) program (in VT100 mode) recognizes the control characters
412 BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.
413 Escape sequences
415 VT100 console sequences not implemented on the Linux console:
417 ESC N SS2 Single shift 2. (Select G2 character set for the next
419 character only.)
420 ESC O SS3 Single shift 3. (Select G3 character set for the next
421 character only.)
422 ESC P DCS Device control string (ended by ESC \)
423 ESC X SOS Start of string.
424 ESC ^ PM Privacy message (ended by ESC \)
425 ESC \ ST String terminator
426 ESC * ... Designate G2 character set
427 ESC + ... Designate G3 character set
428 The program xterm(1) (in VT100 mode) recognizes ESC c, ESC # 8, ESC >,
430 ESC =, ESC D, ESC E, ESC H, ESC M, ESC N, ESC O, ESC P ... ESC \, ESC Z
431 (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with advanced video option")
432 and ESC ^ ... ESC \ with the same meanings as indicated above. It
433 accepts ESC (, ESC ), ESC *, ESC + followed by 0, A, B for the DEC
434 special character and line drawing set, UK, and US-ASCII, respectively.
435 The user can configure xterm(1) to respond to VT220-specific control
437 sequences, and it will identify itself as a VT52, VT100, and up depend‐
438 ing on the way it is configured and initialized.
439 It accepts ESC ] (OSC) for the setting of certain resources. In addi‐
441 tion to the ECMA-48 string terminator (ST), xterm(1) accepts a BEL to
442 terminate an OSC string. These are a few of the OSC control sequences
443 recognized by xterm(1):
444 ESC ] 0 ; txt ST Set icon name and window title to txt.
446 ESC ] 1 ; txt ST Set icon name to txt.
447 ESC ] 2 ; txt ST Set window title to txt.
448 ESC ] 4 ; num; txt ST Set ANSI color num to txt.
449 ESC ] 10 ; txt ST Set dynamic text color to txt.
450 ESC ] 4 6 ; name ST Change log file to name (normally disabled
451 by a compile-time option)
452 ESC ] 5 0 ; fn ST Set font to fn.
453 It recognizes the following with slightly modified meaning (saving more
455 state, behaving closer to VT100/VT220):
456 ESC 7 DECSC Save cursor
458 ESC 8 DECRC Restore cursor
459 It also recognizes
461 ESC F Cursor to lower left corner of screen (if enabled by
463 xterm(1)'s hpLowerleftBugCompat resource)
464 ESC l Memory lock (per HP terminals).
465 Locks memory above the cursor.
466 ESC m Memory unlock (per HP terminals).
468 ESC n LS2 Invoke the G2 character set.
469 ESC o LS3 Invoke the G3 character set.
470 ESC | LS3R Invoke the G3 character set as GR.
471 ESC } LS2R Invoke the G2 character set as GR.
472 ESC ~ LS1R Invoke the G1 character set as GR.
473 It also recognizes ESC % and provides a more complete UTF-8 implementa‐
475 tion than Linux console.
476 CSI Sequences
478 Old versions of xterm(1), for example, from X11R5, interpret the blink
480 SGR as a bold SGR. Later versions which implemented ANSI colors, for
481 example, XFree86 3.1.2A in 1995, improved this by allowing the blink
482 attribute to be displayed as a color. Modern versions of xterm imple‐
483 ment blink SGR as blinking text and still allow colored text as an
484 alternate rendering of SGRs. Stock X11R6 versions did not recognize
485 the color-setting SGRs until the X11R6.8 release, which incorporated
486 XFree86 xterm. All ECMA-48 CSI sequences recognized by Linux are also
487 recognized by xterm, however xterm(1) implements several ECMA-48 and
488 DEC control sequences not recognized by Linux.
489 The xterm(1) program recognizes all of the DEC Private Mode sequences
491 listed above, but none of the Linux private-mode sequences. For dis‐
492 cussion of xterm(1)'s own private-mode sequences, refer to the Xterm
493 Control Sequences document by Edward Moy, Stephen Gildea, and Thomas E.
494 Dickey available with the X distribution. That document, though terse,
495 is much longer than this manual page. For a chronological overview,
496 ⟨http://invisible-island.net/xterm/xterm.log.html⟩
498 details changes to xterm.
500 The vttest program
502 ⟨http://invisible-island.net/vttest/⟩
504 demonstrates many of these control sequences. The xterm(1) source dis‐
506 tribution also contains sample scripts which exercise other features.
507
509 ESC 8 (DECRC) is not able to restore the character set changed with ESC
510 %.
511
513 In 2.0.23, CSI is broken, and NUL is not ignored inside escape
514 sequences.
515 Some older kernel versions (after 2.0) interpret 8-bit control
517 sequences. These "C1 controls" use codes between 128 and 159 to
518 replace ESC [, ESC ] and similar two-byte control sequence initiators.
519 There are fragments of that in modern kernels (either overlooked or
520 broken by changes to support UTF-8), but the implementation is incom‐
521 plete and should be regarded as unreliable.
522 Linux "private mode" sequences do not follow the rules in ECMA-48 for
524 private mode control sequences. In particular, those ending with ] do
525 not use a standard terminating character. The OSC (set palette)
526 sequence is a greater problem, since xterm(1) may interpret this as a
527 control sequence which requires a string terminator (ST). Unlike the
528 setterm(1) sequences which will be ignored (since they are invalid con‐
529 trol sequences), the palette sequence will make xterm(1) appear to hang
530 (though pressing the return-key will fix that). To accommodate appli‐
531 cations which have been hardcoded to use Linux control sequences, set
532 the xterm(1) resource brokenLinuxOSC to true.
533 An older version of this document implied that Linux recognizes the
535 ECMA-48 control sequence for invisible text. It is ignored.
536
538 ioctl_console(2), charsets(7)
539
541 This page is part of release 5.07 of the Linux man-pages project. A
542 description of the project, information about reporting bugs, and the
543 latest version of this page, can be found at
544 https://www.kernel.org/doc/man-pages/.
545Linux 2020-02-09 CONSOLE_CODES(4)