summaryrefslogtreecommitdiffstats
path: root/man4/console_codes.4
blob: e2ac4e86b4ef814dc53711d66d9b5f5762c37131 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
'\" t
.\" Copyright (c) 1996 Andries Brouwer <aeb@cwi.nl>, Mon Oct 31 22:13:04 1996
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" This is combined from many sources.
.\" For Linux, the definitive source is of course console.c.
.\" About vt100-like escape sequences in general there are
.\" the ISO 6429 and ISO 2022 norms, the descriptions of
.\" an actual vt100, and the xterm docs (ctlseqs.ms).
.\" Substantial portions of this text are derived from a write-up
.\" by Eric S. Raymond <esr@thyrsus.com>.
.\"
.\" Tiny correction, aeb, 961107.
.\"
.\" 2006-05-27, Several corrections - Thomas E. Dickey
.\"
.TH console_codes 4 2023-02-05 "Linux man-pages 6.05.01"
.SH NAME
console_codes \- Linux console escape and control sequences
.SH DESCRIPTION
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 without a mnemonic are neither ECMA-48 nor VT102.
.PP
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.
.PP
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 \fBCharacter Sets\fP section below for discussion.
.PP
In the normal case, the Unicode value is converted to a font index,
and this is stored in video memory, so that the corresponding glyph
(as found in video ROM) appears on the screen.
Note that the use of Unicode (and the design of the PC hardware)
allows us to use 512 different glyphs simultaneously.
.PP
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 \fBLinux Console Controls\fP section below for discussion.
.PP
It is generally not good practice to hard-wire terminal controls into
programs.
Linux supports a
.BR terminfo (5)
database of terminal capabilities.
Rather than emitting console escape sequences by hand, you will almost
always want to use a terminfo-aware screen library or utility such as
.BR ncurses (3),
.BR tput (1),
or
.BR reset (1).
.SS 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.
.PP
.B "Control characters"
.PP
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\[en]1f are regarded
as control characters, regardless of any "display control characters"
mode.
.PP
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:
.TP
BEL (0x07, \fB\[ha]G\fP)
beeps;
.TP
BS (0x08, \fB\[ha]H\fP)
backspaces one column
(but not past the beginning of the line);
.TP
HT (0x09, \fB\[ha]I\fP)
goes to the next tab stop or to the end of the line
if there is no earlier tab stop;
.TP
LF (0x0A, \fB\[ha]J\fP)
.TQ
VT (0x0B, \fB\[ha]K\fP)
.TQ
FF (0x0C, \fB\[ha]L\fP)
all give a linefeed,
and if LF/NL (new-line mode) is set also a carriage return;
.TP
CR (0x0D, \fB\[ha]M\fP)
gives a carriage return;
.TP
SO (0x0E, \fB\[ha]N\fP)
activates the G1 character set;
.TP
SI (0x0F, \fB\[ha]O\fP)
activates the G0 character set;
.TP
CAN (0x18, \fB\[ha]X\fP)
.TQ
SUB (0x1A, \fB\[ha]Z\fP)
abort escape sequences;
.TP
ESC (0x1B, \fB\[ha][\fP)
starts an escape sequence;
.TP
DEL (0x7F)
is ignored;
.TP
CSI (0x9B)
is equivalent to ESC [.
.PP
.B "ESC- but not CSI-sequences"
.ad l
.TS
l l lx.
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	T{
DEC private identification. The kernel
returns the string  ESC [ ? 6 c, claiming
that it is a VT102.
T}
ESC 7	DECSC	T{
Save current state (cursor coordinates,
attributes, character sets pointed at by G0, G1).
T}
ESC 8	DECRC	T{
Restore state most recently saved by ESC 7.
T}
ESC %		Start sequence selecting character set
ESC % @		\0\0\0Select default (ISO 646 / ISO 8859-1)
ESC % G		\0\0\0Select UTF-8
ESC % 8		\0\0\0Select UTF-8 (obsolete)
ESC # 8	DECALN	T{
DEC screen alignment test \- fill screen with E's.
T}
ESC (		T{
Start sequence defining G0 character set
(followed by one of B, 0, U, K, as below)
T}
ESC ( B		T{
Select default (ISO 8859-1 mapping).
T}
ESC ( 0		T{
Select VT100 graphics mapping.
T}
ESC ( U		T{
Select null mapping \- straight to character ROM.
T}
ESC ( K		T{
Select user mapping \- the map that is loaded by the utility \fBmapscrn\fP(8).
T}
ESC )		T{
Start sequence defining G1 (followed by one of B, 0, U, K, as above).
T}
ESC >	DECPNM	Set numeric keypad mode
ESC =	DECPAM	Set application keypad mode
ESC ]	OSC	T{
Operating System Command prefix.
T}
ESC ] R		Reset palette.
ESC ] P		T{
Set palette, with parameter given in 7 hexadecimal digits \fInrrggbb\fP after
the final P. Here \fIn\fP is the color (0\[en]15), and \fIrrggbb\fP indicates
the red/green/blue values (0\[en]255).
T}
.TE
.ad
.PP
.B "ECMA-48 CSI sequences"
.PP
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.
.PP
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.)
.PP
The action of a CSI sequence is determined by its final character.
.ad l
.TS
l l lx.
@	ICH	T{
Insert the indicated # of blank characters.
T}
A	CUU	T{
Move cursor up the indicated # of rows.
T}
B	CUD	T{
Move cursor down the indicated # of rows.
T}
C	CUF	T{
Move cursor right the indicated # of columns.
T}
D	CUB	T{
Move cursor left the indicated # of columns.
T}
E	CNL	T{
Move cursor down the indicated # of rows, to column 1.
T}
F	CPL	T{
Move cursor up the indicated # of rows, to column 1.
T}
G	CHA	T{
Move cursor to indicated column in current row.
T}
H	CUP	T{
Move cursor to the indicated row, column (origin at 1,1).
T}
J	ED	T{
Erase display (default: from cursor to end of display).
T}
		T{
ESC [ 1 J: erase from start to cursor.
T}
		T{
ESC [ 2 J: erase whole display.
T}
		T{
ESC [ 3 J: erase whole display including scroll-back
buffer (since Linux 3.0).
T}
.\" ESC [ 3 J: commit f8df13e0a901fe55631fed66562369b4dba40f8b
K	EL	T{
Erase line (default: from cursor to end of line).
T}
		T{
ESC [ 1 K: erase from start of line to cursor.
T}
		T{
ESC [ 2 K: erase whole line.
T}
L	IL	T{
Insert the indicated # of blank lines.
T}
M	DL	T{
Delete the indicated # of lines.
T}
P	DCH	T{
Delete the indicated # of characters on current line.
T}
X	ECH	T{
Erase the indicated # of characters on current line.
T}
a	HPR	T{
Move cursor right the indicated # of columns.
T}
c	DA	T{
Answer ESC [ ? 6 c: "I am a VT102".
T}
d	VPA	T{
Move cursor to the indicated row, current column.
T}
e	VPR	T{
Move cursor down the indicated # of rows.
T}
f	HVP	T{
Move cursor to the indicated row, column.
T}
g	TBC	T{
Without parameter: clear tab stop at current position.
T}
		T{
ESC [ 3 g: delete all tab stops.
T}
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	T{
Set scrolling region; parameters are top and bottom row.
T}
s	?	Save cursor location.
u	?	Restore cursor location.
\`	HPA	T{
Move cursor to indicated column in current row.
T}
.TE
.ad
.PP
.B ECMA-48 Select Graphic Rendition
.PP
The ECMA-48 SGR sequence ESC [ \fIparameters\fP 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 zero.
.ad l
.TS
l lx.
param	result
0	T{
reset all attributes to their defaults
T}
1	set bold
2	T{
set half-bright (simulated with color on a color display)
T}
3	set italic (since Linux 2.6.22; simulated with color on a color display)
4	T{
set underscore (simulated with color on a color display)
(the colors used to simulate dim or underline are set
using ESC ] ...)
T}
5	set blink
7	set reverse video
10	T{
reset selected mapping, display control flag,
and toggle meta flag (ECMA-48 says "primary font").
T}
11	T{
select null mapping, set display control flag,
reset toggle meta flag (ECMA-48 says "first alternate font").
T}
12	T{
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.
T}
21	T{
set underline; before Linux 4.17, this value
set normal intensity (as is done in many other terminals)
T}
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	T{
256/24-bit foreground color follows, shoehorned into 16 basic colors
(before Linux 3.16: set underscore on, set default foreground color)
T}
39	T{
set default foreground color
(before Linux 3.16: set underscore off, set default foreground color)
T}
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	T{
256/24-bit background color follows, shoehorned into 8 basic colors
T}
49	set default background color
90..97	T{
set foreground to bright versions of 30..37
T}
100..107	T{
set background, same as 40..47 (bright not supported)
T}
.TE
.ad
.PP
Commands 38 and 48 require further arguments:
.TS
l lx.
;5;x	T{
256 color: values 0..15 are IBGR (black, red, green, ... white),
16..231 a 6x6x6 color cube, 232..255 a grayscale ramp
T}
;2;r;g;b	T{
24-bit color, r/g/b components are in the range 0..255
T}
.TE
.PP
.B ECMA-48 Mode Switches
.TP
ESC [ 3 h
DECCRM (default off): Display control chars.
.TP
ESC [ 4 h
DECIM (default off): Set insert mode.
.TP
ESC [ 20 h
LF/NL (default off): Automatically follow echo of LF, VT, or FF with CR.
.\"
.PP
.B ECMA-48 Status Report Commands
.\"
.TP
ESC [ 5 n
Device status report (DSR): Answer is ESC [ 0 n (Terminal OK).
.TP
ESC [ 6 n
Cursor position report (CPR): Answer is ESC [ \fIy\fP ; \fIx\fP R,
where \fIx,y\fP is the cursor location.
.\"
.PP
.B DEC Private Mode (DECSET/DECRST) sequences
.PP
.\"
These are not described in ECMA-48.
We list the Set Mode sequences;
the Reset Mode sequences are obtained by replacing the final \[aq]h\[aq]
by \[aq]l\[aq].
.TP
ESC [ ? 1 h
DECCKM (default off): When set, the cursor keys send an ESC O prefix,
rather than ESC [.
.TP
ESC [ ? 3 h
DECCOLM (default off = 80 columns): 80/132 col mode switch.
The driver sources note that this alone does not suffice; some user-mode
utility such as
.BR resizecons (8)
has to change the hardware registers on the console video card.
.TP
ESC [ ? 5 h
DECSCNM (default off): Set reverse-video mode.
.TP
ESC [ ? 6 h
DECOM (default off): When set, cursor addressing is relative to
the upper left corner of the scrolling region.
.TP
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.
.TP
ESC [ ? 8 h
DECARM (default on): Set keyboard autorepeat on.
.TP
ESC [ ? 9 h
X10 Mouse Reporting (default off): Set reporting mode to 1 (or reset to
0)\[em]see below.
.TP
ESC [ ? 25 h
DECTECM (default on): Make cursor visible.
.TP
ESC [ ? 1000 h
X11 Mouse Reporting (default off): Set reporting mode to 2 (or reset
to 0)\[em]see below.
.\"
.PP
.B Linux Console Private CSI Sequences
.PP
.\"
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\[en]15 = bright versions of 0\[en]7.
.TS
l lx.
ESC [ 1 ; \fIn\fP ]	T{
Set color \fIn\fP as the underline color.
T}
ESC [ 2 ; \fIn\fP ]	T{
Set color \fIn\fP as the dim color.
T}
ESC [ 8 ]       	T{
Make the current color pair the default attributes.
T}
ESC [ 9 ; \fIn\fP ]	T{
Set screen blank timeout to \fIn\fP minutes.
T}
ESC [ 10 ; \fIn\fP ]	T{
Set bell frequency in Hz.
T}
ESC [ 11 ; \fIn\fP ]	T{
Set bell duration in msec.
T}
ESC [ 12 ; \fIn\fP ]	T{
Bring specified console to the front.
T}
ESC [ 13 ]      	T{
Unblank the screen.
T}
ESC [ 14 ; \fIn\fP ]   	T{
Set the VESA powerdown interval in minutes.
T}
ESC [ 15 ]	T{
Bring the previous console to the front
(since Linux 2.6.0).
T}
ESC [ 16 ; \fIn\fP ]	T{
Set the cursor blink interval in milliseconds
(since Linux 4.2).
T}
.\" commit bd63364caa8df38bad2b25b11b2a1b849475cce5
.TE
.SS 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.
.PP
There are two character sets, called G0 and G1, and one of them
is the current character set.
(Initially G0.)
Typing \fB\[ha]N\fP causes G1 to become current,
\fB\[ha]O\fP causes G0 to become current.
.PP
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.
.PP
The sequence ESC c causes a terminal reset, which is what you want if the
screen is all garbled.
The oft-advised "echo \[ha]V\[ha]O" will make only G0 current,
but there is no guarantee that G0 points at table a).
In some distributions there is a program
.BR reset (1)
that just does "echo \[ha][c".
If your terminfo entry for the console is correct
(and has an entry rs1=\eEc), then "tput reset" will also work.
.PP
The user-defined mapping table can be set using
.BR 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
.BR setfont (8).
.SS Mouse tracking
The mouse tracking facility is intended to return
.BR 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
.BR gpm (8)
daemon.
.PP
The mouse tracking escape sequences generated by
\fBxterm\fP(1) encode numeric parameters in a single character as
\fIvalue\fP+040.
For example, \[aq]!\[aq] is 1.
The screen coordinate system is 1-based.
.PP
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, \fBxterm\fP(1) sends
ESC [ M \fIbxy\fP (6 characters).
Here \fIb\fP is button\-1,
and \fIx\fP and \fIy\fP are the x and y coordinates of the mouse
when the button was pressed.
This is the same code the kernel also produces.
.PP
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 release, \fBxterm\fP(1) sends ESC [ M
\fIbxy\fP.
The low two bits of \fIb\fP 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 \fIx\fP and
\fIy\fP are the x and y coordinates of the mouse event.
The upper left corner is (1,1).
.SS Comparisons with other terminals
Many different terminal types are described, like the Linux console,
as being "VT100-compatible".
Here we discuss differences between the
Linux console and the two most important others, the DEC VT102 and
.BR xterm (1).
.\"
.PP
.B Control-character handling
.PP
The VT102 also recognized the following control characters:
.TP
NUL (0x00)
was ignored;
.TP
ENQ (0x05)
triggered an answerback message;
.TP
DC1 (0x11, \fB\[ha]Q\fP, XON)
resumed transmission;
.TP
DC3 (0x13, \fB\[ha]S\fP, XOFF)
caused VT100 to ignore (and stop transmitting)
all codes except XOFF and XON.
.PP
VT100-like DC1/DC3 processing may be enabled by the terminal driver.
.PP
The
.BR xterm (1)
program (in VT100 mode) recognizes the control characters
BEL, BS, HT, LF, VT, FF, CR, SO, SI, ESC.
.\"
.PP
.B Escape sequences
.PP
VT100 console sequences not implemented on the Linux console:
.TS
l l l.
ESC N	SS2	T{
Single shift 2. (Select G2 character set for the next character only.)
T}
ESC O	SS3	T{
Single shift 3. (Select G3 character set for the next character only.)
T}
ESC P	DCS	T{
Device control string (ended by ESC \e)
T}
ESC X	SOS	Start of string.
ESC \[ha]	PM	Privacy message (ended by ESC \e)
ESC \e	ST	String terminator
ESC * ...		Designate G2 character set
ESC + ...		Designate G3 character set
.TE
.PP
The program
.BR 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 \e,
ESC Z (it answers ESC [ ? 1 ; 2 c, "I am a VT100 with
advanced video option")
and ESC \[ha] ... ESC \e 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.
.PP
The user can configure \fBxterm\fP(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.
.PP
It accepts ESC ] (OSC) for the setting of certain resources.
In addition to the ECMA-48 string terminator (ST),
\fBxterm\fP(1) accepts a BEL to terminate an OSC string.
These are a few of the OSC control sequences recognized by \fBxterm\fP(1):
.TS
l l.
ESC ] 0 ; \fItxt\fP ST	T{
Set icon name and window title to \fItxt\fP.
T}
ESC ] 1 ; \fItxt\fP ST	Set icon name to \fItxt\fP.
ESC ] 2 ; \fItxt\fP ST	Set window title to \fItxt\fP.
ESC ] 4 ; \fInum\fP; \fItxt\fP ST	Set ANSI color \fInum\fP to \fItxt\fP.
ESC ] 10 ; \fItxt\fP ST	Set dynamic text color to \fItxt\fP.
ESC ] 4 6 ; \fIname\fP ST	T{
Change log file to \fIname\fP (normally disabled by a compile-time option).
T}
ESC ] 5 0 ; \fIfn\fP ST	Set font to \fIfn\fP.
.TE
.PP
It recognizes the following with slightly modified meaning
(saving more state, behaving closer to VT100/VT220):
.TS
l l l.
ESC 7  DECSC	Save cursor
ESC 8  DECRC	Restore cursor
.TE
.PP
It also recognizes
.TS
l l lx.
ESC F		T{
Cursor to lower left corner of screen (if enabled
by \fBxterm\fP(1)'s \fBhpLowerleftBugCompat\fP resource).
T}
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.
ESC }	LS2R	Invoke the G2 character set as GR.
ESC \[ti]	LS1R	Invoke the G1 character set as GR.
.TE
.PP
It also recognizes ESC % and provides a more complete UTF-8
implementation than Linux console.
.\"
.PP
.B CSI Sequences
.PP
Old versions of \fBxterm\fP(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
.IR xterm ,
however \fBxterm\fP(1) implements several ECMA-48 and DEC control sequences
not recognized by Linux.
.PP
The \fBxterm\fP(1)
program recognizes all of the DEC Private Mode sequences listed
above, but none of the Linux private-mode sequences.
For discussion of \fBxterm\fP(1)'s
own private-mode sequences, refer to the
\fIXterm Control Sequences\fP
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,
.PP
.RS
.UR http://invisible\-island.net\:/xterm\:/xterm.log.html
.UE
.RE
.PP
details changes to xterm.
.PP
The \fIvttest\fP program
.PP
.RS
.UR http://invisible\-island.net\:/vttest/
.UE
.RE
.PP
demonstrates many of these control sequences.
The \fBxterm\fP(1) source distribution also contains sample
scripts which exercise other features.
.SH NOTES
ESC 8 (DECRC) is not able to restore the character set changed with
ESC %.
.SH BUGS
In Linux 2.0.23, CSI is broken, and NUL is not ignored inside
escape sequences.
.PP
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 regarded
as unreliable.
.PP
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 \fBxterm\fP(1) may interpret this as a control sequence
which requires a string terminator (ST).
Unlike the \fBsetterm\fP(1) sequences which will be ignored (since
they are invalid control sequences), the palette sequence will make
\fBxterm\fP(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 \fBxterm\fP(1) resource \fBbrokenLinuxOSC\fP to true.
.PP
An older version of this document implied that Linux recognizes the
ECMA-48 control sequence for invisible text.
It is ignored.
.SH SEE ALSO
.BR ioctl_console (2),
.BR charsets (7)