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) interrupt 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 normal intensity (ECMA-48 says "doubly underlined")
210 22 set normal intensity
211 24 underline off
212 25 blink off
213 27 reverse video off
214 30 set black foreground
215 31 set red foreground
216 32 set green foreground
217 33 set brown foreground
218 34 set blue foreground
219 35 set magenta foreground
220 36 set cyan foreground
221 37 set white foreground
222 38 set underscore on, set default foreground color
223 39 set underscore off, set default foreground color
224 40 set black background
225 41 set red background
226 42 set green background
227 43 set brown background
228 44 set blue background
229 45 set magenta background
230 46 set cyan background
231 47 set white background
232 49 set default background color
233 ECMA-48 Mode Switches
235 ESC [ 3 h
237 DECCRM (default off): Display control chars.
238 ESC [ 4 h
240 DECIM (default off): Set insert mode.
241 ESC [ 20 h
243 LF/NL (default off): Automatically follow echo of LF, VT or FF
244 with CR.
245 ECMA-48 Status Report Commands
247 ESC [ 5 n
249 Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).
250 ESC [ 6 n
252 Cursor position report (CPR): Answer is ESC [ y ; x R, where x,y
253 is the cursor location.
254 DEC Private Mode (DECSET/DECRST) sequences
256 These are not described in ECMA-48. We list the Set Mode sequences;
258 the Reset Mode sequences are obtained by replacing the final 'h' by
259 'l'.
260 ESC [ ? 1 h
262 DECCKM (default off): When set, the cursor keys send an ESC O
263 prefix, rather than ESC [.
264 ESC [ ? 3 h
266 DECCOLM (default off = 80 columns): 80/132 col mode switch. The
267 driver sources note that this alone does not suffice; some user-
268 mode utility such as resizecons(8) has to change the hardware
269 registers on the console video card.
270 ESC [ ? 5 h
272 DECSCNM (default off): Set reverse-video mode.
273 ESC [ ? 6 h
275 DECOM (default off): When set, cursor addressing is relative to
276 the upper left corner of the scrolling region.
277 ESC [ ? 7 h
279 DECAWM (default on): Set autowrap on. In this mode, a graphic
280 character emitted after column 80 (or column 132 of DECCOLM is
281 on) forces a wrap to the beginning of the following line first.
282 ESC [ ? 8 h
284 DECARM (default on): Set keyboard autorepeat on.
285 ESC [ ? 9 h
287 X10 Mouse Reporting (default off): Set reporting mode to 1 (or
288 reset to 0)—see below.
289 ESC [ ? 25 h
291 DECTECM (default on): Make cursor visible.
292 ESC [ ? 1000 h
294 X11 Mouse Reporting (default off): Set reporting mode to 2 (or
295 reset to 0)—see below.
296 Linux Console Private CSI Sequences
298 The following sequences are neither ECMA-48 nor native VT102. They are
300 native to the Linux console driver. Colors are in SGR parameters: 0 =
301 black, 1 = red, 2 = green, 3 = brown, 4 = blue, 5 = magenta, 6 = cyan,
302 7 = white; 8–15 = bright versions of 0–7.
303 ESC [ 1 ; n ] Set color n as the underline color.
305 ESC [ 2 ; n ] Set color n as the dim color.
306 ESC [ 8 ] Make the current color pair the default attributes.
307 ESC [ 9 ; n ] Set screen blank timeout to n minutes.
308 ESC [ 10 ; n ] Set bell frequency in Hz.
309 ESC [ 11 ; n ] Set bell duration in msec.
310 ESC [ 12 ; n ] Bring specified console to the front.
311 ESC [ 13 ] Unblank the screen.
312 ESC [ 14 ; n ] Set the VESA powerdown interval in minutes.
313 ESC [ 15 ] Bring the previous console to the front (since
314 Linux 2.6.0).
315 ESC [ 16 ; n ] Set the cursor blink interval in milliseconds
316 (since Linux 4.2).
317 Character sets
319 The kernel knows about 4 translations of bytes into console-screen sym‐
320 bols. The four tables are: a) Latin1 -> PC, b) VT100 graphics -> PC,
321 c) PC -> PC, d) user-defined.
322 There are two character sets, called G0 and G1, and one of them is the
324 current character set. (Initially G0.) Typing ^N causes G1 to become
325 current, ^O causes G0 to become current.
326 These variables G0 and G1 point at a translation table, and can be
328 changed by the user. Initially they point at tables a) and b), respec‐
329 tively. The sequences ESC ( B and ESC ( 0 and ESC ( U and ESC ( K
330 cause G0 to point at translation table a), b), c) and d), respectively.
331 The sequences ESC ) B and ESC ) 0 and ESC ) U and ESC ) K cause G1 to
332 point at translation table a), b), c) and d), respectively.
333 The sequence ESC c causes a terminal reset, which is what you want if
335 the screen is all garbled. The oft-advised "echo ^V^O" will make only
336 G0 current, but there is no guarantee that G0 points at table a). In
337 some distributions there is a program reset(1) that just does "echo
338 ^[c". If your terminfo entry for the console is correct (and has an
339 entry rs1=\Ec), then "tput reset" will also work.
340 The user-defined mapping table can be set using mapscrn(8). The result
342 of the mapping is that if a symbol c is printed, the symbol s = map[c]
343 is sent to the video memory. The bitmap that corresponds to s is found
344 in the character ROM, and can be changed using setfont(8).
345 Mouse tracking
347 The mouse tracking facility is intended to return xterm(1)-compatible
348 mouse status reports. Because the console driver has no way to know
349 the device or type of the mouse, these reports are returned in the con‐
350 sole input stream only when the virtual terminal driver receives a
351 mouse update ioctl. These ioctls must be generated by a mouse-aware
352 user-mode application such as the gpm(8) daemon.
353 The mouse tracking escape sequences generated by xterm(1) encode
355 numeric parameters in a single character as value+040. For example,
356 '!' is 1. The screen coordinate system is 1-based.
357 The X10 compatibility mode sends an escape sequence on button press
359 encoding the location and the mouse button pressed. It is enabled by
360 sending ESC [ ? 9 h and disabled with ESC [ ? 9 l. On button press,
361 xterm(1) sends ESC [ M bxy (6 characters). Here b is button-1, and x
362 and y are the x and y coordinates of the mouse when the button was
363 pressed. This is the same code the kernel also produces.
364 Normal tracking mode (not implemented in Linux 2.0.24) sends an escape
366 sequence on both button press and release. Modifier information is
367 also sent. It is enabled by sending ESC [ ? 1000 h and disabled with
368 ESC [ ? 1000 l. On button press or release, xterm(1) sends ESC [ M
369 bxy. The low two bits of b encode button information: 0=MB1 pressed,
370 1=MB2 pressed, 2=MB3 pressed, 3=release. The upper bits encode what
371 modifiers were down when the button was pressed and are added together:
372 4=Shift, 8=Meta, 16=Control. Again x and y are the x and y coordinates
373 of the mouse event. The upper left corner is (1,1).
374 Comparisons with other terminals
376 Many different terminal types are described, like the Linux console, as
377 being "VT100-compatible". Here we discuss differences between the
378 Linux console and the two most important others, the DEC VT102 and
379 xterm(1).
380 Control-character handling
382 The VT102 also recognized the following control characters:
384 NUL (0x00) was ignored;
386 ENQ (0x05) triggered an answerback message;
388 DC1 (0x11, ^Q, XON) resumed transmission;
390 DC3 (0x13, ^S, XOFF) caused VT100 to ignore (and stop transmitting) all
392 codes except XOFF and XON.
393 VT100-like DC1/DC3 processing may be enabled by the terminal driver.
395 The xterm(1) program (in VT100 mode) recognizes the control characters
397 BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.
398 Escape sequences
400 VT100 console sequences not implemented on the Linux console:
402 ESC N SS2 Single shift 2. (Select G2 character set for the next
404 character only.)
405 ESC O SS3 Single shift 3. (Select G3 character set for the next
406 character only.)
407 ESC P DCS Device control string (ended by ESC \)
408 ESC X SOS Start of string.
409 ESC ^ PM Privacy message (ended by ESC \)
410 ESC \ ST String terminator
411 ESC * ... Designate G2 character set
412 ESC + ... Designate G3 character set
413 The program xterm(1) (in VT100 mode) recognizes ESC c, ESC # 8, ESC >,
415 ESC =, ESC D, ESC E, ESC H, ESC M, ESC N, ESC O, ESC P ... ESC \, ESC Z
416 (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with advanced video option")
417 and ESC ^ ... ESC \ with the same meanings as indicated above. It
418 accepts ESC (, ESC ), ESC *, ESC + followed by 0, A, B for the DEC
419 special character and line drawing set, UK, and US-ASCII, respectively.
420 The user can configure xterm(1) to respond to VT220-specific control
422 sequences, and it will identify itself as a VT52, VT100, and up depend‐
423 ing on the way it is configured and initialized.
424 It accepts ESC ] (OSC) for the setting of certain resources. In addi‐
426 tion to the ECMA-48 string terminator (ST), xterm(1) accepts a BEL to
427 terminate an OSC string. These are a few of the OSC control sequences
428 recognized by xterm(1):
429 ESC ] 0 ; txt ST Set icon name and window title to txt.
431 ESC ] 1 ; txt ST Set icon name to txt.
432 ESC ] 2 ; txt ST Set window title to txt.
433 ESC ] 4 ; num; txt ST Set ANSI color num to txt.
434 ESC ] 10 ; txt ST Set dynamic text color to txt.
435 ESC ] 4 6 ; name ST Change log file to name (normally disabled
436 by a compile-time option)
437 ESC ] 5 0 ; fn ST Set font to fn.
438 It recognizes the following with slightly modified meaning (saving more
440 state, behaving closer to VT100/VT220):
441 ESC 7 DECSC Save cursor
443 ESC 8 DECRC Restore cursor
444 It also recognizes
446 ESC F Cursor to lower left corner of screen (if enabled by
448 xterm(1)'s hpLowerleftBugCompat resource)
449 ESC l Memory lock (per HP terminals).
450 Locks memory above the cursor.
451 ESC m Memory unlock (per HP terminals).
452 ESC n LS2 Invoke the G2 character set.
453 ESC o LS3 Invoke the G3 character set.
454 ESC | LS3R Invoke the G3 character set as GR.
455 ESC } LS2R Invoke the G2 character set as GR.
456 ESC ~ LS1R Invoke the G1 character set as GR.
457 It also recognizes ESC % and provides a more complete UTF-8 implementa‐
459 tion than Linux console.
460 CSI Sequences
462 Old versions of xterm(1), for example, from X11R5, interpret the blink
464 SGR as a bold SGR. Later versions which implemented ANSI colors, for
465 example, XFree86 3.1.2A in 1995, improved this by allowing the blink
466 attribute to be displayed as a color. Modern versions of xterm imple‐
467 ment blink SGR as blinking text and still allow colored text as an
468 alternate rendering of SGRs. Stock X11R6 versions did not recognize
469 the color-setting SGRs until the X11R6.8 release, which incorporated
470 XFree86 xterm. All ECMA-48 CSI sequences recognized by Linux are also
471 recognized by xterm, however xterm(1) implements several ECMA-48 and
472 DEC control sequences not recognized by Linux.
473 The xterm(1) program recognizes all of the DEC Private Mode sequences
475 listed above, but none of the Linux private-mode sequences. For dis‐
476 cussion of xterm(1)'s own private-mode sequences, refer to the Xterm
477 Control Sequences document by Edward Moy, Stephen Gildea, and Thomas E.
478 Dickey available with the X distribution. That document, though terse,
479 is much longer than this manual page. For a chronological overview,
480 ⟨http://invisible-island.net/xterm/xterm.log.html⟩
482 details changes to xterm.
484 The vttest program
486 ⟨http://invisible-island.net/vttest/⟩
488 demonstrates many of these control sequences. The xterm(1) source dis‐
490 tribution also contains sample scripts which exercise other features.
491
493 ESC 8 (DECRC) is not able to restore the character set changed with ESC
494 %.
495
497 In 2.0.23, CSI is broken, and NUL is not ignored inside escape
498 sequences.
499 Some older kernel versions (after 2.0) interpret 8-bit control
501 sequences. These "C1 controls" use codes between 128 and 159 to
502 replace ESC [, ESC ] and similar two-byte control sequence initiators.
503 There are fragments of that in modern kernels (either overlooked or
504 broken by changes to support UTF-8), but the implementation is incom‐
505 plete and should be regarded as unreliable.
506 Linux "private mode" sequences do not follow the rules in ECMA-48 for
508 private mode control sequences. In particular, those ending with ] do
509 not use a standard terminating character. The OSC (set palette)
510 sequence is a greater problem, since xterm(1) may interpret this as a
511 control sequence which requires a string terminator (ST). Unlike the
512 setterm(1) sequences which will be ignored (since they are invalid con‐
513 trol sequences), the palette sequence will make xterm(1) appear to hang
514 (though pressing the return-key will fix that). To accommodate appli‐
515 cations which have been hardcoded to use Linux control sequences, set
516 the xterm(1) resource brokenLinuxOSC to true.
517 An older version of this document implied that Linux recognizes the
519 ECMA-48 control sequence for invisible text. It is ignored.
520
522 ioctl_console(2), charsets(7)
523
525 This page is part of release 5.02 of the Linux man-pages project. A
526 description of the project, information about reporting bugs, and the
527 latest version of this page, can be found at
528 https://www.kernel.org/doc/man-pages/.
529Linux 2019-03-06 CONSOLE_CODES(4)