1CONSOLE_CODES(4) Linux Programmer's Manual CONSOLE_CODES(4)
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6 console_codes - Linux console escape and control sequences
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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 etc. 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 K EL Erase line (default: from cursor to end of line).
155 ESC [ 1 K: erase from start of line to cursor.
156 ESC [ 2 K: erase whole line.
157 L IL Insert the indicated # of blank lines.
158 M DL Delete the indicated # of lines.
159 P DCH Delete the indicated # of characters on the current line.
160 X ECH Erase the indicated # of characters on the current line.
161 a HPR Move cursor right the indicated # of columns.
162 c DA Answer ESC [ ? 6 c: "I am a VT102".
163 d VPA Move cursor to the indicated row, current column.
164 e VPR Move cursor down the indicated # of rows.
165 f HVP Move cursor to the indicated row, column.
166 g TBC Without parameter: clear tab stop at the current position.
167 ESC [ 3 g: delete all tab stops.
168 h SM Set Mode (see below).
169 l RM Reset Mode (see below).
170 m SGR Set attributes (see below).
171 n DSR Status report (see below).
172 q DECLL Set keyboard LEDs.
173 ESC [ 0 q: clear all LEDs
174 ESC [ 1 q: set Scroll Lock LED
175 ESC [ 2 q: set Num Lock LED
176 ESC [ 3 q: set Caps Lock LED
177 r DECSTBM Set scrolling region; parameters are top and bottom row.
178 s ? Save cursor location.
179 u ? Restore cursor location.
180 ` HPA Move cursor to indicated column in current row.
181 ECMA-48 Set Graphics Rendition
183 The ECMA-48 SGR sequence ESC [ parameters m sets display attributes.
185 Several attributes can be set in the same sequence, separated by semi‐
186 colons. An empty parameter (between semicolons or string initiator or
187 terminator) is interpreted as a zero.
188 param result
190 0 reset all attributes to their defaults
191 1 set bold
192 2 set half-bright (simulated with color on a color display)
193 4 set underscore (simulated with color on a color display)
194 (the colors used to simulate dim or underline are set
195 using ESC ] ...)
196 5 set blink
197 7 set reverse video
198 10 reset selected mapping, display control flag, and toggle
200 meta flag (ECMA-48 says "primary font").
201 11 select null mapping, set display control flag, reset tog‐
202 gle meta flag (ECMA-48 says "first alternate font").
203 12 select null mapping, set display control flag, set toggle
204 meta flag (ECMA-48 says "second alternate font"). The
205 toggle meta flag causes the high bit of a byte to be tog‐
206 gled before the mapping table translation is done.
207 21 set normal intensity (ECMA-48 says "doubly underlined")
208 22 set normal intensity
209 24 underline off
210 25 blink off
211 27 reverse video off
212 30 set black foreground
213 31 set red foreground
214 32 set green foreground
215 33 set brown foreground
216 34 set blue foreground
217 35 set magenta foreground
218 36 set cyan foreground
219 37 set white foreground
220 38 set underscore on, set default foreground color
221 39 set underscore off, set default foreground color
222 40 set black background
223 41 set red background
224 42 set green background
225 43 set brown background
226 44 set blue background
227 45 set magenta background
228 46 set cyan background
229 47 set white background
230 49 set default background color
231 ECMA-48 Mode Switches
233 ESC [ 3 h
235 DECCRM (default off): Display control chars.
236 ESC [ 4 h
238 DECIM (default off): Set insert mode.
239 ESC [ 20 h
241 LF/NL (default off): Automatically follow echo of LF, VT or FF
242 with CR.
243 ECMA-48 Status Report Commands
245 ESC [ 5 n
247 Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).
248 ESC [ 6 n
250 Cursor position report (CPR): Answer is ESC [ y ; x R, where x,y
251 is the cursor location.
252 DEC Private Mode (DECSET/DECRST) sequences
254 These are not described in ECMA-48. We list the Set Mode sequences;
256 the Reset Mode sequences are obtained by replacing the final 'h' by
257 'l'.
258 ESC [ ? 1 h
260 DECCKM (default off): When set, the cursor keys send an ESC O
261 prefix, rather than ESC [.
262 ESC [ ? 3 h
264 DECCOLM (default off = 80 columns): 80/132 col mode switch. The
265 driver sources note that this alone does not suffice; some user-
266 mode utility such as resizecons(8) has to change the hardware
267 registers on the console video card.
268 ESC [ ? 5 h
270 DECSCNM (default off): Set reverse-video mode.
271 ESC [ ? 6 h
273 DECOM (default off): When set, cursor addressing is relative to
274 the upper left corner of the scrolling region.
275 ESC [ ? 7 h
277 DECAWM (default on): Set autowrap on. In this mode, a graphic
278 character emitted after column 80 (or column 132 of DECCOLM is
279 on) forces a wrap to the beginning of the following line first.
280 ESC [ ? 8 h
282 DECARM (default on): Set keyboard autorepeat on.
283 ESC [ ? 9 h
285 X10 Mouse Reporting (default off): Set reporting mode to 1 (or
286 reset to 0) — see below.
287 ESC [ ? 25 h
289 DECTECM (default on): Make cursor visible.
290 ESC [ ? 1000 h
292 X11 Mouse Reporting (default off): Set reporting mode to 2 (or
293 reset to 0) — see below.
294 Linux Console Private CSI Sequences
296 The following sequences are neither ECMA-48 nor native VT102. They are
298 native to the Linux console driver. Colors are in SGR parameters: 0 =
299 black, 1 = red, 2 = green, 3 = brown, 4 = blue, 5 = magenta, 6 = cyan,
300 7 = white.
301 ESC [ 1 ; n ] Set color n as the underline color
303 ESC [ 2 ; n ] Set color n as the dim color
304 ESC [ 8 ] Make the current color pair the default attributes.
305 ESC [ 9 ; n ] Set screen blank timeout to n minutes.
306 ESC [ 10 ; n ] Set bell frequency in Hz.
307 ESC [ 11 ; n ] Set bell duration in msec.
308 ESC [ 12 ; n ] Bring specified console to the front.
309 ESC [ 13 ] Unblank the screen.
310 ESC [ 14 ; n ] Set the VESA powerdown interval in minutes.
311 Character Sets
313 The kernel knows about 4 translations of bytes into console-screen sym‐
314 bols. The four tables are: a) Latin1 -> PC, b) VT100 graphics -> PC,
315 c) PC -> PC, d) user-defined.
316 There are two character sets, called G0 and G1, and one of them is the
318 current character set. (Initially G0.) Typing ^N causes G1 to become
319 current, ^O causes G0 to become current.
320 These variables G0 and G1 point at a translation table, and can be
322 changed by the user. Initially they point at tables a) and b), respec‐
323 tively. The sequences ESC ( B and ESC ( 0 and ESC ( U and ESC ( K
324 cause G0 to point at translation table a), b), c) and d), respectively.
325 The sequences ESC ) B and ESC ) 0 and ESC ) U and ESC ) K cause G1 to
326 point at translation table a), b), c) and d), respectively.
327 The sequence ESC c causes a terminal reset, which is what you want if
329 the screen is all garbled. The oft-advised "echo ^V^O" will only make
330 G0 current, but there is no guarantee that G0 points at table a). In
331 some distributions there is a program reset(1) that just does "echo
332 ^[c". If your terminfo entry for the console is correct (and has an
333 entry rs1=\Ec), then "tput reset" will also work.
334 The user-defined mapping table can be set using mapscrn(8). The result
336 of the mapping is that if a symbol c is printed, the symbol s = map[c]
337 is sent to the video memory. The bitmap that corresponds to s is found
338 in the character ROM, and can be changed using setfont(8).
339 Mouse Tracking
341 The mouse tracking facility is intended to return xterm(1)-compatible
342 mouse status reports. Because the console driver has no way to know
343 the device or type of the mouse, these reports are returned in the con‐
344 sole input stream only when the virtual terminal driver receives a
345 mouse update ioctl. These ioctls must be generated by a mouse-aware
346 user-mode application such as the gpm(8) daemon.
347 The mouse tracking escape sequences generated by xterm(1) encode
349 numeric parameters in a single character as value+040. For example,
350 '!' is 1. The screen coordinate system is 1-based.
351 The X10 compatibility mode sends an escape sequence on button press
353 encoding the location and the mouse button pressed. It is enabled by
354 sending ESC [ ? 9 h and disabled with ESC [ ? 9 l. On button press,
355 xterm(1) sends ESC [ M bxy (6 characters). Here b is button-1, and x
356 and y are the x and y coordinates of the mouse when the button was
357 pressed. This is the same code the kernel also produces.
358 Normal tracking mode (not implemented in Linux 2.0.24) sends an escape
360 sequence on both button press and release. Modifier information is
361 also sent. It is enabled by sending ESC [ ? 1000 h and disabled with
362 ESC [ ? 1000 l. On button press or release, xterm(1) sends ESC [ M
363 bxy. The low two bits of b encode button information: 0=MB1 pressed,
364 1=MB2 pressed, 2=MB3 pressed, 3=release. The upper bits encode what
365 modifiers were down when the button was pressed and are added together:
366 4=Shift, 8=Meta, 16=Control. Again x and y are the x and y coordinates
367 of the mouse event. The upper left corner is (1,1).
368 Comparisons With Other Terminals
370 Many different terminal types are described, like the Linux console, as
371 being "VT100-compatible". Here we discuss differences between the
372 Linux console and the two most important others, the DEC VT102 and
373 xterm(1).
374 Control-character handling
376 The VT102 also recognized the following control characters:
378 NUL (0x00) was ignored;
380 ENQ (0x05) triggered an answerback message;
382 DC1 (0x11, ^Q, XON) resumed transmission;
384 DC3 (0x13, ^S, XOFF) caused VT100 to ignore (and stop transmitting) all
386 codes except XOFF and XON.
387 VT100-like DC1/DC3 processing may be enabled by the tty driver.
389 The xterm(1) program (in VT100 mode) recognizes the control characters
391 BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.
392 Escape sequences
394 VT100 console sequences not implemented on the Linux console:
396 ESC N SS2 Single shift 2. (Select G2 character set for the next
398 character only.)
399 ESC O SS3 Single shift 3. (Select G3 character set for the next
401 character only.)
402 ESC P DCS Device control string (ended by ESC \)
403 ESC X SOS Start of string.
404 ESC ^ PM Privacy message (ended by ESC \)
405 ESC \ ST String terminator
406 ESC * ... Designate G2 character set
407 ESC + ... Designate G3 character set
408 The program xterm(1) (in VT100 mode) recognizes ESC c, ESC # 8, ESC >,
410 ESC =, ESC D, ESC E, ESC H, ESC M, ESC N, ESC O, ESC P ... ESC \, ESC Z
411 (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with advanced video option")
412 and ESC ^ ... ESC \ with the same meanings as indicated above. It
413 accepts ESC (, ESC ), ESC *, ESC + followed by 0, A, B for the DEC
414 special character and line drawing set, UK, and US-ASCII, respectively.
415 The user can configure xterm(1) to respond to VT220-specific control
417 sequences, and it will identify itself as a VT52, VT100, and up depend‐
418 ing on the way it is configured and initialized.
419 It accepts ESC ] (OSC) for the setting of certain resources. In addi‐
421 tion to the ECMA-48 string terminator (ST), xterm(1) accepts a BEL to
422 terminate an OSC string. These are a few of the OSC control sequences
423 recognized by xterm(1):
424 ESC ] 0 ; txt ST Set icon name and window title to txt.
426 ESC ] 1 ; txt ST Set icon name to txt.
427 ESC ] 2 ; txt ST Set window title to txt.
428 ESC ] 4 ; num; txt ST Set ANSI color num to txt.
429 ESC ] 10 ; txt ST Set dynamic text color to txt.
430 ESC ] 4 6 ; name ST Change log file to name (normally disabled
431 by a compile-time option)
432 ESC ] 5 0 ; fn ST Set font to fn.
433 It recognizes the following with slightly modified meaning (saving more
435 state, behaving closer to VT100/VT220):
436 ESC 7 DECSC Save cursor
438 ESC 8 DECRC Restore cursor
439 It also recognizes
441 ESC F Cursor to lower left corner of screen (if enabled by
443 xterm(1)'s hpLowerleftBugCompat resource)
444 ESC l Memory lock (per HP terminals).
445 Locks memory above the cursor.
446 ESC m Memory unlock (per HP terminals).
447 ESC n LS2 Invoke the G2 character set.
448 ESC o LS3 Invoke the G3 character set.
449 ESC | LS3R Invoke the G3 character set as GR.
450 ESC } LS2R Invoke the G2 character set as GR.
451 ESC ~ LS1R Invoke the G1 character set as GR.
452 It also recognizes ESC % and provides a more complete UTF-8 implementa‐
454 tion than Linux console.
455 CSI Sequences
457 Old versions of xterm(1), for example, from X11R5, interpret the blink
459 SGR as a bold SGR. Later versions which implemented ANSI colors, for
460 example, XFree86 3.1.2A in 1995, improved this by allowing the blink
461 attribute to be displayed as a color. Modern versions of xterm imple‐
462 ment blink SGR as blinking text and still allow colored text as an
463 alternate rendering of SGRs. Stock X11R6 versions did not recognize
464 the color-setting SGRs until the X11R6.8 release, which incorporated
465 XFree86 xterm. All ECMA-48 CSI sequences recognized by Linux are also
466 recognized by xterm, however xterm(1) implements several ECMA-48 and
467 DEC control sequences not recognized by Linux.
468 The xterm(1) program recognizes all of the DEC Private Mode sequences
470 listed above, but none of the Linux private-mode sequences. For dis‐
471 cussion of xterm(1)'s own private-mode sequences, refer to the Xterm
472 Control Sequences document by Edward Moy, Stephen Gildea, and Thomas E.
473 Dickey available with the X distribution. That document, though terse,
474 is much longer than this manual page. For a chronological overview,
475 http://invisible-island.net/xterm/xterm.log.html
477 details changes to xterm.
479 The vttest program
481 http://invisible-island.net/vttest/
483 demonstrates many of these control sequences. The xterm(1) source dis‐
485 tribution also contains sample scripts which exercise other features.
486
488 ESC 8 (DECRC) is not able to restore the character set changed with ESC
489 %.
490
492 In 2.0.23, CSI is broken, and NUL is not ignored inside escape
493 sequences.
494 Some older kernel versions (after 2.0) interpret 8-bit control
496 sequences. These "C1 controls" use codes between 128 and 159 to
497 replace ESC [, ESC ] and similar two-byte control sequence initiators.
498 There are fragments of that in modern kernels (either overlooked or
499 broken by changes to support UTF-8), but the implementation is incom‐
500 plete and should be regarded as unreliable.
501 Linux "private mode" sequences do not follow the rules in ECMA-48 for
503 private mode control sequences. In particular, those ending with ] do
504 not use a standard terminating character. The OSC (set palette)
505 sequence is a greater problem, since xterm(1) may interpret this as a
506 control sequence which requires a string terminator (ST). Unlike the
507 setterm(1) sequences which will be ignored (since they are invalid con‐
508 trol sequences), the palette sequence will make xterm(1) appear to hang
509 (though pressing the return-key will fix that). To accommodate appli‐
510 cations which have been hardcoded to use Linux control sequences, set
511 the xterm(1) resource brokenLinuxOSC to true.
512 An older version of this document implied that Linux recognizes the
514 ECMA-48 control sequence for invisible text. It is ignored.
515
517 console(4), console_ioctl(4), charsets(7)
518
520 This page is part of release 3.22 of the Linux man-pages project. A
521 description of the project, and information about reporting bugs, can
522 be found at http://www.kernel.org/doc/man-pages/.
523Linux 2008-01-01 CONSOLE_CODES(4)