ANSI escape code

ANSI escape sequences are a standard for in-band signaling to control the cursor location, color, and other options on video text terminals and terminal emulators. Certain sequences of bytes, most starting with Esc and '[', are embedded into the text, which the terminal looks for and interprets as commands, not as character codes.

ANSI sequences were introduced in the 1970s to replace vendor-specific sequences and became widespread in the computer equipment market by the early 1980s. They were used in development, scientific and commercial applications and later by the nascent bulletin board systems to offer improved displays compared to earlier systems lacking cursor movement, a primary reason they became a standard adopted by all manufacturers.

Although hardware text terminals have become increasingly rare in the 21st century, the relevance of the ANSI standard persists because most terminal emulators interpret at least some of the ANSI escape sequences in output text. A notable exception was DOS and older versions of the Win32 console of Microsoft Windows.

History

Almost all manufacturers of video terminals added vendor-specific escape sequences to perform operations such as placing the cursor at arbitrary positions on the screen. One example is the VT52 terminal, which allowed the cursor to be placed at an x,y location on the screen by sending the ESC character, a y character, and then two characters representing with numerical values equal to the x,y location plus 32 (thus starting at the ASCII space character and avoiding the control characters).

As these sequences were different for different terminals, elaborate libraries such as termcap and utilities such as tput had to be created so programs could use the same API to work with any terminal. In addition many of these terminals required sending numbers (such as row and column) as the binary values of the characters; for some programming languages, and for systems that did not use ASCII internally, it was often difficult or impossible to turn a number into the correct character.

The ANSI standard attempted to address these problems by making a command set that all terminals would use and requiring all numeric information to be transmitted as ASCII numbers. The first standard in the series was ECMA-48, adopted in 1976. It was a continuation of a series of character coding standards, the first one being ECMA-6 from 1965, a 7-bit standard from which ISO 646 originates. The name "ANSI escape sequence" dates from 1979 when ANSI adopted ANSI X3.64. The ANSI X3L2 committee collaborated with the ECMA committee TC 1 to produce nearly identical standards. These two standards were merged into an international standard, ISO 6429.[1] In 1994, ANSI withdrew its standard in favor of the international standard.

The first popular video terminal to support these sequences was the Digital VT100, introduced in 1978.[2] This model was very successful in the market, which sparked a variety of VT100 clones, among the earliest and most popular of which was the much more affordable Zenith Z-19 in 1979.[3] Others included the Qume QVT-108, Televideo TVI-970, Wyse WY-99GT as well as optional "VT100" or "VT103" or "ANSI" modes with varying degrees of compatibility on many other brands. The popularity of these gradually led to more and more software (especially bulletin board systems and other online services) assuming the escape sequences worked, leading to almost all new terminals and emulator programs supporting them.

In 1981, ANSI X3.64 was adopted for use in the US government by FIPS publication 86. Later, the US government stopped duplicating industry standards, so FIPS pub. 86 was withdrawn.[4]

ECMA-48 has been updated several times and is currently at its 5th edition, from 1991. It is also adopted by ISO and IEC as standard ISO/IEC 6429.

Platform support

Unix-like systems

Although termcap/terminfo-style libraries were primarily developed on and for Unix, since about 1984 programs running on Unix-like operating systems could almost always assume they were using a terminal or emulator that supported ANSI sequences; this led to widespread use of ANSI by programs running on those platforms. For instance, many games and shell scripts (see below for colored prompt examples), and utilities such as color directory listings, directly write the ANSI sequences and thus cannot be used on a terminal that does not interpret them. Many programs, including text editors such as vi and GNU Emacs, still use termcap or terminfo, or use libraries such as curses that use termcap or terminfo, and thus in theory support non-ANSI terminals, but this is so rarely tested nowadays that they are unlikely to work with those terminals. Terminal emulators for communicating with local programs as well as remote machines and the text system console almost always support ANSI escape codes.

DOS

MS-DOS 1.x did not support the ANSI or any other escape sequences. Only a few control characters (BEL, CR, LF, BS) were interpreted by the underlying BIOS, making it almost[nb 1] impossible to do any kind of full-screen application. Any display effects had to be done with BIOS calls, which were notoriously slow, or by directly manipulating the IBM PC hardware.

DOS 2.0 introduced the ability to add a device driver for the ANSI escape sequences – the de facto standard being ANSI.SYS, but others like ANSI.COM,[5] NANSI.SYS[6] and ANSIPLUS.EXE are used as well (these are considerably faster as they bypass the BIOS). Slowness and the fact that it was not installed by default made software rarely take advantage of it; instead, applications continued to directly manipulate the hardware to get the text display needed. ANSI.SYS and similar drivers continued to work in Windows 9x up to Windows Me, and in NT-derived systems for 16-bit legacy programs executing under the NTVDM.

PTS-DOS[7][8] as well as Concurrent DOS, Multiuser DOS[9] and REAL/32 have built-in support for ANSI ecape sequences (plus a number of extensions) and do not require a separate ANSI driver to be loaded.

OS/2

The ANSI command in a batch file or at the command line enables the extensions.

Atari ST

The Atari ST used the command system adapted from the VT52 with some expansions for color support,[10] rather than supporting ANSI escape codes.

AmigaOS

AmigaOS not only interprets ANSI code sequences for text output to the screen, the AmigaOS printer driver also interprets them (with extensions proprietary to AmigaOS) and translates them into the codes required for the particular printer that is actually attached.[11]

Windows

The Win32 console did not originally support ANSI escape sequences. Some replacements or additions for the console window such as JP Software's TCC (formerly 4NT), Michael J. Mefford's ANSI.COM, Jason Hood's ANSICON[12] and Maximus5's ConEmu interpreted ANSI escape sequences printed by programs. A Python package[13] internally interpreted ANSI escape sequences in text being printed, translating them to calls to manipulate the color and cursor position, to make it easier to port Python code using ANSI to Windows.

In 2016, Microsoft released the Windows 10 Version 1511 update which unexpectedly implemented support for ANSI escape sequences[14]. The change was designed to complement the Windows Subsystem for Linux, adding to the Windows Console Host used by Command Prompt support for character escape codes used by terminal-based software for Unix-like systems. This is not the default behavior and must be enabled by enabled programmatically with the Win32 API via SetConsoleMode(handle, ENABLE_VIRTUAL_TERMINAL_PROCESSING).[15] This was enabled by CMD.EXE but not initially by PowerShell[16] however, Windows PowerShell 5.1 now enables this by default. The ability to make a string constant containing ESC was added in PowerShell 6 with (for example) "`e[32m",[17] for PowerShell 5 you had to use [char]0x1b+"[32m".

Escape sequences

Sequences have different lengths. All sequences start with ESC (27 / hex 0x1B / octal 033), followed by a second byte in the range 0x40–0x5F (ASCII @A–Z[\]^_).[18]:5.3.a

The standard says that in 8-bit environments these two-byte sequences can be merged into single C1 control code in the 0x80–0x9F range.[18]:5.4.a However on modern devices those codes are often used for other purposes, such as parts of UTF-8 or for CP-1252 characters, so only the 2-byte sequence is used.

Other C0 codes besides ESC — commonly BEL, BS, CR, LF, FF, TAB, VT, SO, and SI — produce similar or identical effects to some control sequences when output.

Some ANSI escape sequences (not an exhaustive list)
Sequence C1 Name Effect
ESC N 0x8e SS2 – Single Shift Two Select a single character from one of the alternative character sets. In xterm, SS2 selects the G2 character set, and SS3 selects the G3 character set.[19]
ESC O 0x8f SS3 – Single Shift Three
ESC P 0x90 DCS – Device Control String Terminated by ST. Xterm's uses of this sequence include defining User-Defined Keys, and requesting or setting Termcap/Terminfo data.[19]
ESC [ 0x9b CSI - Control Sequence Introducer Most of the useful sequences, see next section.
ESC \ 0x9c ST – String Terminator Terminates strings in other controls.[18]:8.3.143
ESC ] 0x9d OSC – Operating System Command Starts a control string for the operating system to use, terminated by ST.[18]:8.3.89 In xterm, they may also be terminated by BEL.[19] In xterm, the window title can be set by OSC 0;this is the window title BEL.
ESC X 0x98 SOS – Start of String Takes an argument of a string of text, terminated by ST. The uses for these string control sequences are defined by the application[18]:8.3.2,8.3.128 or privacy discipline.[18]:8.3.94 These functions are not implemented and the arguments are ignored by xterm.[19]
ESC ^ 0x9e PM – Privacy Message
ESC _ 0x9f APC – Application Program Command
ESC c RIS – Reset to Initial State Resets the device to its original state. This may include (if applicable): reset graphic rendition, clear tabulation stops, reset to default font, and more.

Pressing special keys on the keyboard, as well as outputting many xterm CSI, DCS, or OSC sequences, often produces a CSI, DCS, or OSC sequence, sent from the terminal to the computer as though the user typed it.

CSI sequences

The ESC [ is followed by any number (including none) of "parameter bytes" in the range 0x30–0x3F (ASCII 0–9:;<=>?), then by any number of "intermediate bytes" in the range 0x20–0x2F (ASCII space and !"#$%&'()*+,-./), then finally by a single "final byte" in the range 0x40–0x7E (ASCII @A–Z[\]^_`a–z{|}~).[18]:5.4

All common sequences just use the parameters as a series of semicolon-separated numbers such as 1;2;3. Missing numbers are treated as 0 (1;;3 acts like the middle number is 0, and no parameters at all in ESC[m acts like a 0 reset code). Some sequences (such as CUU) treat 0 as 1 in order to make missing parameters useful.[18]:F.4.2 Bytes other than digits and semicolon seem to not be used.

A subset of arrangements was declared "private" so that terminal manufacturers could insert their own sequences without conflicting with the standard. Sequences containing the parameter bytes <=>? or the final bytes 0x70–0x7E (p–z{|}~) are private.

The behavior of the terminal is undefined in the case where a CSI sequence contains any character outside of the range 0x20–0x7E. These illegal characters are either C0 control characters (the range 0–0x1F), DEL (0x7F), or bytes with the high bit set. Possible responses are to ignore the byte, to process it immediately, and furthermore whether to continue with the CSI sequence, to abort it immediately, or to ignore the rest of it.

Some ANSI control sequences (not an exhaustive list)
Code Name Effect
CSI n A CUU – Cursor Up Moves the cursor n (default 1) cells in the given direction. If the cursor is already at the edge of the screen, this has no effect.
CSI n B CUD – Cursor Down
CSI n C CUF – Cursor Forward
CSI n D CUB – Cursor Back
CSI n E CNL – Cursor Next Line Moves cursor to beginning of the line n (default 1) lines down. (not ANSI.SYS)
CSI n F CPL – Cursor Previous Line Moves cursor to beginning of the line n (default 1) lines up. (not ANSI.SYS)
CSI n G CHA – Cursor Horizontal Absolute Moves the cursor to column n (default 1). (not ANSI.SYS)
CSI n ; m H CUP – Cursor Position Moves the cursor to row n, column m. The values are 1-based, and default to 1 (top left corner) if omitted. A sequence such as CSI ;5H is a synonym for CSI 1;5H as well as CSI 17;H is the same as CSI 17H and CSI 17;1H
CSI n J ED – Erase in Display Clears part of the screen. If n is 0 (or missing), clear from cursor to end of screen. If n is 1, clear from cursor to beginning of the screen. If n is 2, clear entire screen (and moves cursor to upper left on DOS ANSI.SYS). If n is 3, clear entire screen and delete all lines saved in the scrollback buffer (this feature was added for xterm and is supported by other terminal applications).
CSI n K EL – Erase in Line Erases part of the line. If n is 0 (or missing), clear from cursor to the end of the line. If n is 1, clear from cursor to beginning of the line. If n is 2, clear entire line. Cursor position does not change.
CSI n S SU – Scroll Up Scroll whole page up by n (default 1) lines. New lines are added at the bottom. (not ANSI.SYS)
CSI n T SD – Scroll Down Scroll whole page down by n (default 1) lines. New lines are added at the top. (not ANSI.SYS)
CSI n ; m f HVP – Horizontal Vertical Position Same as CUP
CSI n m SGR – Select Graphic Rendition Sets the appearance of the following characters, see SGR parameters below.
CSI 5i AUX Port On Enable aux serial port usually for local serial printer
CSI 4i AUX Port Off Disable aux serial port usually for local serial printer
CSI 6n DSR – Device Status Report Reports the cursor position (CPR) to the application as (as though typed at the keyboard) ESC[n;mR, where n is the row and m is the column.)
CSI s SCP – Save Cursor Position Saves the cursor position/state.
CSI u RCP – Restore Cursor Position Restores the cursor position/state.
Some popular private sequences
Code Effect
CSI ? 25 h DECTCEM Shows the cursor, from the VT320.
CSI ? 25 l DECTCEM Hides the cursor.
CSI ? 1049 h Enable alternative screen buffer
CSI ? 1049 l Disable alternative screen buffer
CSI ? 2004 h Turn on bracketed paste mode. Text pasted into the terminal will be surrounded by ESC [200~ and ESC [201~, and characters in it should not be treated as commands (for example in Vim).[20] From Unix terminal emulators.
CSI ? 2004 l Turn off bracketed paste mode.

SGR (Select Graphic Rendition) parameters

SGR sets display attributes. Several attributes can be set in the same sequence, separated by semicolons.[21] Each display attribute remains in effect until a following occurrence of SGR resets it.[1] If no codes are given, CSI m is treated as CSI 0 m (reset / normal).

In ECMA-48 SGR is called "Select Graphic Rendition".[1] In Linux manual pages the term "Set Graphics Rendition" is used.[21]

Code Effect Note
0 Reset / Normal all attributes off
1 Bold or increased intensity
2 Faint (decreased intensity)
3 Italic Not widely supported. Sometimes treated as inverse.
4 Underline
5 Slow Blink less than 150 per minute
6 Rapid Blink MS-DOS ANSI.SYS; 150+ per minute; not widely supported
7 reverse video swap foreground and background colors
8 Conceal Not widely supported.
9 Crossed-out Characters legible, but marked for deletion.
10 Primary(default) font
11–19 Alternative font Select alternative font
20 Fraktur Rarely supported
21 Doubly underline or Bold off Double-underline per ECMA-48.[22] See discussion
22 Normal color or intensity Neither bold nor faint
23 Not italic, not Fraktur
24 Underline off Not singly or doubly underlined
25 Blink off
27 Inverse off
28 Reveal conceal off
29 Not crossed out
30–37 Set foreground color See color table below
38 Set foreground color Next arguments are 5;n or 2;r;g;b, see below
39 Default foreground color implementation defined (according to standard)
40–47 Set background color See color table below
48 Set background color Next arguments are 5;n or 2;r;g;b, see below
49 Default background color implementation defined (according to standard)
51 Framed
52 Encircled
53 Overlined
54 Not framed or encircled
55 Not overlined
60 ideogram underline or right side line Rarely supported
61 ideogram double underline or
double line on the right side
62 ideogram overline or left side line
63 ideogram double overline or
double line on the left side
64 ideogram stress marking
65 ideogram attributes off reset the effects of all of 6064
90–97 Set bright foreground color aixterm (not in standard)
100–107 Set bright background color aixterm (not in standard)

Colors

3/4 bit

The original specification only had 8 colors, and just gave them names. The SGR parameters 30-37 selected the foreground color, while 40-47 selected the background. Quite a few terminals implemented "bold" (SGR code 1) as a brighter color rather than a different font, thus providing 8 additional foreground colors. Usually you could not get these as background colors, though sometimes inverse video (SGR code 7) would allow that. Examples: to get black letters on white background use ESC[30;47m, to get red use ESC[31m, to get bright red use ESC[1;31m. To reset colors to their defaults, use ESC[39;49m (not supported on some terminals), or reset all attributes with ESC[0m. Later terminals added the ability to directly specify the "bright" colors with 90-97 and 100-107.

When hardware started using 8-bit DACs several pieces of software assigned 24-bit color numbers to these names. The chart below shows values sent to the DAC for some common hardware and software.

Name FG Code BG Code VGA[nb 2] Windows Console[nb 3] PowerShell Terminal.app PuTTY mIRC xterm X[nb 4] Ubuntu[nb 5]
Black 30 40 0,0,0 1,1,1
Red 31 41 170,0,0 128,0,0 128,0,0 194,54,33 187,0,0 127,0,0 205,0,0 255,0,0 222,56,43
Green 32 42 0,170,0 0,128,0 0,128,0 37,188,36 0,187,0 0,147,0 0,205,0 0,255,0 57,181,74
Yellow 33 43 170,85,0[nb 6] 128,128,0 238,237,240 173,173,39 187,187,0 252,127,0 205,205,0 255,255,0 255,199,6
Blue 34 44 0,0,170 0,0,128 0,0,128 73,46,225 0,0,187 0,0,127 0,0,238[23] 0,0,255 0,111,184
Magenta 35 45 170,0,170 128,0,128 1,36,86 211,56,211 187,0,187 156,0,156 205,0,205 255,0,255 118,38,113
Cyan 36 46 0,170,170 0,128,128 0,128,128 51,187,200 0,187,187 0,147,147 0,205,205 0,255,255 44,181,233
White 37 47 170,170,170 192,192,192 192,192,192 203,204,205 187,187,187 210,210,210 229,229,229 255,255,255 204,204,204
Bright Black 90 100 85,85,85 128,128,128 128,128,128 129,131,131 85,85,85 127,127,127 127,127,127 128,128,128
Bright Red 91 101 255,85,85 255,0,0 255,0,0 252,57,31 255,85,85 255,0,0 255,0,0 255,0,0
Bright Green 92 102 85,255,85 0,255,0 0,255,0 49,231,34 85,255,85 0,252,0 0,255,0 144,238,144 0,255,0
Bright Yellow 93 103 255,255,85 255,255,0 255,255,0 234,236,35 255,255,85 255,255,0 255,255,0 255,255,224 255,255,0
Bright Blue 94 104 85,85,255 0,0,255 0,0,255 88,51,255 85,85,255 0,0,252 92,92,255[24] 173,216,230 0,0,255
Bright Magenta 95 105 255,85,255 255,0,255 255,0,255 249,53,248 255,85,255 255,0,255 255,0,255 255,0,255
Bright Cyan 96 106 85,255,255 0,255,255 0,255,255 20,240,240 85,255,255 0,255,255 0,255,255 224,255,255 0,255,255
Bright White 97 107 255,255,255 255,255,255 255,255,255 233,235,235 255,255,255 255,255,255 255,255,255 255,255,255

8-bit

As 256-color lookup tables became common on graphic cards, escape sequences were added to select from a pre-defined set of 256 colors:

   ESC[ 38;5;<n> m Select foreground color
   ESC[ 48;5;<n> m Select background color
     0-  7:  standard colors (as in ESC [ 30–37 m)
     8- 15:  high intensity colors (as in ESC [ 90–97 m)
    16-231:  6 × 6 × 6 cube (216 colors): 16 + 36 × r + 6 × g + b (0 ≤ r, g, b ≤ 5)
   232-255:  grayscale from black to white in 24 steps

The ITU's T.416 Information technology - Open Document Architecture (ODA) and interchange format: Character content architectures[25] uses ':' as separator characters instead:

   ESC[ 38:5:<n> m Select foreground color
   ESC[ 48:5:<n> m Select background color

24-bit

As "true color" graphic cards with 16 to 24 bits of color became common, Xterm,[19] KDE's Konsole,[26] as well as all libvte based terminals[27] (including GNOME Terminal) support 24-bit foreground and background color setting[28]

   ESC[ 38;2;<r>;<g>;<b> m Select RGB foreground color
   ESC[ 48;2;<r>;<g>;<b> m Select RGB background color

The ITU's T.416 Information technology - Open Document Architecture (ODA) and interchange format: Character content architectures[25] which was adopted as ISO/IEC International Standard 8613-6 gives an alternative version that seems to be less supported:

   ESC[ 38:2:<Color-Space-ID>:<r>:<g>:<b>:<unused>:<CS tolerance>:<Color-Space associated with tolerance: 0="CIELUV"; 1="CIELAB">; m Select RGB foreground color
   ESC[ 48:2:<Color-Space-ID>:<r>:<g>:<b>:<unused>:<CS tolerance>:<Color-Space associated with tolerance: 0="CIELUV"; 1="CIELAB">; m Select RGB background color

Note that this uses the otherwise reserved ':' character to separate the sub-options which may have been a source of confusion for real-world implementations. It also documents using '3' as the second parameter to specify colors using a Cyan-Magenta-Yellow scheme and '4' for a Cyan-Magenta-Yellow-Black one, the latter using the position marked as "unused" in the above examples for the Black component.

Also note that many implementation that recognize ':' as the separator erroneously forget about the color space identifier parameter and hence shift the position of the remaining ones.

Examples

CSI 2 J — This clears the screen and, on some devices, locates the cursor to the y,x position 1,1 (upper left corner).

CSI 32 m — This makes text green. The green may be a dark, dull green, so you may wish to enable Bold with the sequence CSI 1 m which would make it bright green, or combined as CSI 32 ; 1 m. Some implementations use the Bold state to make the character Bright.

CSI 0 ; 6 8 ; "DIR" ; 13 p — This reassigns the key F10 to send to the keyboard buffer the string "DIR" and ENTER, which in the DOS command line would display the contents of the current directory. (MS-DOS ANSI.SYS only) This was sometimes used for ANSI bombs. This is a private-use code (as indicated by the letter p), using a non-standard extension to include a string-valued parameter. Following the letter of the standard would consider the sequence to end at the letter D.

CSI s — This saves the cursor position. Using the sequence CSI u will restore it to the position. Say the current cursor position is 7(y) and 10(x). The sequence CSI s will save those two numbers. Now you can move to a different cursor position, such as 20(y) and 3(x), using the sequence CSI 20 ; 3 H or CSI 20 ; 3 f. Now if you use the sequence CSI u the cursor position will return to 7(y) and 10(x). Some terminals require the DEC sequences ESC 7 / ESC 8 instead which is more widely supported.

Example of use in shell scripting

ANSI escape codes are often used in UNIX and UNIX-like terminals to provide syntax highlighting. For example, on compatible terminals, the following list command color-codes file and directory names by type.

ls --color

Users can employ escape codes in their scripts by including them as part of standard output or standard error. For example, the following GNU sed command embellishes the output of the make command by displaying lines containing words starting with "WARN" in reverse video and words starting with "ERR" in bright yellow on a dark red background (letter case is ignored). The representations of the codes are highlighted.[29]

make 2>&1 | sed -e 's/.*\bWARN.*/\x1b[7m&\x1b[0m/i' -e 's/.*\bERR.*/\x1b[93;41m&\x1b[0m/i'

The following Bash function flashes the terminal (by alternately sending reverse and normal video mode codes) until the user presses a key.[30]

flasher () { while true; do printf \\e[?5h; sleep 0.1; printf \\e[?5l; read -s -n1 -t1 && break; done; }

This can be used to alert a programmer when a lengthy command terminates, such as with make ; flasher .[31]

printf \\033c

This will reset the console, similar to the command reset on modern Linux systems; however it should work even on older Linux systems and on other (non-Linux) UNIX variants.

Invalid and ambiguous sequences in use

  • The Linux console uses OSC P n rr gg bb to change the palette, which, if hard-coded into an application, may hang other terminals. However, appending ST will be ignored by Linux and form a proper, ignorable sequence for other terminals.
  • On the Linux console, certain function keys generate sequences of the form CSI [ char. The CSI sequence should terminate on the [.
  • Old versions of Terminator generate SS3 1; modifiers char when F1–F4 are pressed with modifiers. The faulty behavior was copied from GNOME Terminal.
  • xterm replies CSI row ; column R if asked for cursor position and CSI 1 ; modifiers R if the F3 key is pressed with modifiers, which collide in the case of row == 1. This can be avoided by using the ? private modifier, which will be reflected in the response.
  • many terminals prepend ESC to any character that is typed with the alt key down. This creates ambiguity for uppercase letters and symbols @[\]^_, which would form C1 codes.
  • Konsole generates SS3 modifiers char when F1–F4 are pressed with modifiers.

See also

Notes

  1. ^ The screen display could be replaced by drawing the entire new screen's contents at the bottom, scrolling the previous screen up sufficiently to erase all the old text. The user would see the scrolling, and the hardware cursor would be left at the very bottom. Some early batch files achieved rudimentary "full screen" displays in this way.
  2. ^ Typical colors that are used when booting PCs and leaving them in text mode, which used a 16-entry color table. The colors are different in the EGA/VGA graphic modes.
  3. ^ As of Windows XP
  4. ^ Above color name from X11 rgb.txt color database, with "light" prefixed for the bright colors.
  5. ^ For virtual terminals, from /etc/vtrgb.
  6. ^ On terminals based on CGA compatible hardware, such as ANSI.SYS running on DOS, this normal intensity foreground color is rendered as Orange. CGA RGBI monitors contained hardware to modify the dark yellow color to an orange/brown color by reducing the green component. See this ansi art Archived 25 July 2011 at the Wayback Machine as an example.

References

  1. ^ a b c "Standard ECMA-48: Control Functions for Character-Imaging I/O Devices" (PDF) (Second ed.). Ecma International. August 1979.
  2. ^ Williams, Paul (2006). "Digital's Video Terminals". VT100.net. Retrieved 2011-08-17.
  3. ^ Heathkit Company (1979). "Heathkit Catalog 1979". Heathkit Company. Archived from the original on 2012-01-13. Retrieved 2011-11-04.
  4. ^ "Withdrawn FIPS Listed by Number" (PDF). National Institute of Standards and Technology. December 15, 2016.
  5. ^ Mefford, Michael (1989-02-07). "ANSI.com: Download It Here". PC Magazine. Retrieved 2011-08-10.
  6. ^ Kegel, Dan; Auer, Eric (1999-02-28). "Nansi and NNansi – ANSI Drivers for MS-DOS". Dan Kegel's Web Hostel. Retrieved 2011-08-10.
  7. ^ "PTS-DOS 2000 Pro User Manual" (PDF). Buggingen, Germany: Paragon Technology GmbH. 1999. Archived (PDF) from the original on 2018-05-12. Retrieved 2018-05-12.
  8. ^ Günther, Jens; Ernst, Tobias (2004-04-25) [1996]. Ellsässer, Wolfgang, ed. "Inoffizielle deutschsprachige PTS-DOS-FAQ (PTS/FAQD)" [Inofficial German PTS-DOS FAQ] (in German). Retrieved 2018-10-02.
  9. ^ CCI Multiuser DOS 7.22 GOLD Online Documentation. Concurrent Controls, Inc. (CCI). 1997-02-10. HELP.HLP.
  10. ^ "Using C-Kermit", p. 88.
  11. ^ "Amiga Printer Command Definitions". Commodore. Retrieved 2013-07-10.
  12. ^ Hood, Jason (2005). "Process ANSI escape sequences for Windows console programs". Jason Hood's Home page. Retrieved 2013-05-09.
  13. ^ "colorama 0.2.5 :". Python Package Index. Retrieved 2013-08-17.
  14. ^ bitcrazed. "Console Virtual Terminal Sequences - Windows Console". docs.microsoft.com. Retrieved 2018-05-30.
  15. ^ "Windows 10 Creators Update: What's new in Bash/WSL & Windows Console". Comment by ulrichb and reply by Rick Turner.
  16. ^ Grehan, Oisin (2016-02-04). "Windows 10 TH2 (v1511) Console Host Enhancements". Retrieved 2016-02-10.;
  17. ^ "PowerShell Help: About Special Characters".
  18. ^ a b c d e f g h "Standard ECMA-48: Control Functions for Coded Character Sets" (Fifth ed.). Ecma International. June 1991.
  19. ^ a b c d e "XTerm Control Sequences". invisible-island.net. 2014-01-13. Retrieved 2014-04-13.
  20. ^ Conrad Irwin (April 2013). "bracketed paste mode". cirw.in.
  21. ^ a b "console_codes(4) - Linux manual page". man7.org. Retrieved 2018-03-23.
  22. ^ ECMA International. "Control Functions for Coded Character Sets" (PDF). p. 61 on printed page, PDF page 75.
  23. ^ Changed from 0,0,205 in July 2004 "Patch #192 – 2004/7/12 – XFree86 4.4.99.9".
  24. ^ Changed from 0,0,255 in July 2004 "Patch #192 – 2004/7/12 – XFree86 4.4.99.9".
  25. ^ a b "T.416 Information technology - Open Document Architecture (ODA) and interchange format: Character content architectures".
  26. ^ "color-spaces.pl (a copy of 256colors2.pl from xterm dated 1999-07-11)". KDE. 2006-12-06.
  27. ^ "libvte's bug report and patches". GNOME Bugzilla. 2014-04-04. Retrieved 2016-06-05.
  28. ^ "README.moreColors". KDE. 2010-04-22.
  29. ^ "Chapter 9. System tips". debian.org.
  30. ^ "VT100.net: Digital VT100 User Guide". Retrieved 2015-01-19.
  31. ^ "bash – How to get a notification when my commands are done – Ask Different". Retrieved 2015-01-19.

External links

ANSI.SYS

ANSI.SYS is a device driver in the DOS family of operating systems that provides extra console functions through ANSI escape sequences. It is partially based upon a subset of the text terminal control standard proposed by the ANSI X3L2 Technical Committee on Codes and Character Sets (the "X3 Committee").

As it was not installed by default, and was notoriously slow, little software took advantage of it and instead resorted to directly manipulating the IBM PC hardware. A number of third-party alternatives that ran at reasonable speed were created, such as ANSI.COM, NANSI.SYS and ANSIPLUS.EXE to attempt to change this. However in the end the fact that software directly manipulated the hardware caused display technology to be quite stagnant until Windows, which used a device driver, became popular.

ANSI art

ANSI art is a computer art form that was widely used at one time on BBSes. It is similar to ASCII art, but constructed from a larger set of 256 letters, numbers, and symbols — all codes found in IBM code page 437, often referred to as extended ASCII and used in MS-DOS and Unix environments. ANSI art also contains special ANSI escape sequences that color text with the 16 foreground and 8 background colours offered by ANSI.SYS, an MS-DOS device driver loosely based upon the ANSI X3.64 standard for text terminals. Some ANSI artists take advantage of the cursor control sequences within ANSI X3.64 in order to create animations, commonly referred to as ANSImations. ANSI art and text files which incorporate ANSI codes carry the de facto .ANS file extension.

ASCII

ASCII ( (listen) ASS-kee), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Most modern character-encoding schemes are based on ASCII, although they support many additional characters.

ASCII is the traditional name for the encoding system; the Internet Assigned Numbers Authority (IANA) prefers the updated name US-ASCII, which clarifies that this system was developed in the US and based on the typographical symbols predominantly in use there.ASCII is one of the IEEE milestones.

Advanced Video Attribute Terminal Assembler and Recreator

The Advanced Video Attribute Terminal Assembler and Recreator (AVATAR) protocol is a system of escape sequences occasionally used on bulletin board systems (BBSes). Its basic level was designed explicitly as a compression of the much longer ANSI escape codes, and can thus render colored text and artwork faster over slow connections. Even when the terminal didn't understand it, the data on disk could use the AVATAR format and so take up less space. Note: A much more comprehensive protocol was proposed, but never gained much support.

The basic protocol is defined by FidoNet technical standard proposal FSC-0025.Avatar was later extended in late 1989 to AVT/0 (sometimes referred to as AVT/0+) which included facilities to scroll areas of the screen (useful for split screen chat, or full screen mail writing programs), as well as more advanced pattern compression. These extensions were not convertible directly into sequences understood by existing ANSI terminals but instead mirrored extra facilities available in the IBM PC BIOS.

Avatar was originally implemented in the Opus BBS, but later popularised by RemoteAccess. RemoteAccess came with a utility, AVTCONV that allowed for easy translation of ANSI documents into Avatar helping its adoption.

Algerian Institute of Standardization

The Algerian Institute of Standardization (Arabic: المعهد الجزائري للتقييس‎) (AIOS-IANOR), was erected in a public industrial and commercial fields (EPIC) by Executive Decree No. 98-69 of February 21, 1998 as part of restructuring INAPI (Algerian Institute of Standardization and Industrial Property).

BIOS color attributes

BIOS Color Attribute is an 8 bit value where the low 4 bits represent the character color and the high 4 bits represent the background color. For example, to print a white character 'A' with black background, the "BIOS Color Attribute" would be set to the hexadecimal value 0x0F. The highest bit of the color attribute, which is also the highest bit of the background color can take over two functions. It can either have no influence on the background color making text blink when set, effectively limiting the available background colors to only eight, or if intensive background colors are enabled the full 16 colors become available but blinking is no longer available. This behavior can be changed, i.e., using BIOS 80x86 interrupt 0x10, function 0x1003. This 16 colour palette is often used in console programs (e.g. cmd in Windows) and sometimes for chat in games (e.g. Minecraft).

Bulletin board system

A bulletin board system or BBS (also called Computer Bulletin Board Service, CBBS) is a computer server running software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging messages with other users through public message boards and sometimes via direct chatting. In the middle to late 1980s, message aggregators and bulk store-and-forward'ers sprung up to provide services such as FidoNet, which is similar to email.

Many BBSes also offer online games in which users can compete with each other. BBSes with multiple phone lines often provide chat rooms, allowing users to interact with each other. Bulletin board systems were in many ways a precursor to the modern form of the World Wide Web, social networks, and other aspects of the Internet. Low-cost, high-performance modems drove the use of online services and BBSes through the early 1990s. Infoworld estimated that there were 60,000 BBSes serving 17 million users in the United States alone in 1994, a collective market much larger than major online services such as CompuServe.

The introduction of inexpensive dial-up internet service and the Mosaic web browser offered ease of use and global access that BBS and online systems did not provide, and led to a rapid crash in the market starting in 1994. Over the next year, many of the leading BBS software providers went bankrupt and tens of thousands of BBSes disappeared. Today, BBSing survives largely as a nostalgic hobby in most parts of the world, but it is still an extremely popular form of communication for Taiwanese youth (see PTT Bulletin Board System). Most surviving BBSes are accessible over Telnet and typically offer free email accounts, FTP services, IRC and all the protocols commonly used on the Internet. Some offer access through packet switched networks or packet radio connections.

C0 and C1 control codes

The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use the ISO/IEC 2022 system of specifying control and graphic characters. Most character encodings, in addition to representing printable characters, also have characters such as these that represent additional information about the text, such as the position of a cursor, an instruction to start a new line, or a message that the text has been received.

The C0 set defines codes in the range 00HEX–1FHEX and the C1 set defines codes in the range 80HEX–9FHEX. The default C0 set was originally defined in ISO 646 (ASCII), while the default C1 set was originally defined in ECMA-48 (harmonized later with ISO 6429). While other C0 and C1 sets are available for specialized applications, they are rarely used.

Computer terminal

A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying or printing data from, a computer or a computing system. The teletype was an example of an early day hardcopy terminal, and predated the use of a computer screen by decades.The acronym CRT (cathode-ray tube), which once referred to a computer terminal, has come to refer to the screen of a personal computer.Early terminals were inexpensive devices but very slow compared to punched cards or paper tape for input, but as the technology improved and video displays were introduced, terminals pushed these older forms of interaction from the industry. A related development was timesharing systems, which evolved in parallel and made up for any inefficiencies of the user's typing ability with the ability to support multiple users on the same machine, each at their own terminal.

The function of a terminal is confined to display and input of data; a device with significant local programmable data processing capability may be called a "smart terminal" or fat client. A terminal that depends on the host computer for its processing power is called a "dumb terminal" or a thin client. A personal computer can run terminal emulator software that replicates the function of a terminal, sometimes allowing concurrent use of local programs and access to a distant terminal host system.

Echo (command)

In computing, echo is a command that outputs the strings it is being passed as arguments. It is a command typically used in shell scripts and batch files to output status text to the screen or a computer file, or as a source part of a pipeline.

GNOME Terminal

GNOME Terminal is a terminal emulator for the GNOME desktop environment written by Havoc Pennington and others. Terminal emulators allow users to access a UNIX shell while remaining on their graphical desktop.

Jason Scott

Jason Scott Sadofsky (born September 13, 1970), more commonly known as Jason Scott, is an American archivist, historian of technology, filmmaker, performer, and actor. Scott has been known by the online pseudonyms Sketch, SketchCow, and The Slipped Disk. He has been called "figurehead of the digital archiving world".He is the creator, owner and maintainer of textfiles.com, a web site which archives files from historic bulletin board systems. He is the creator of a 2005 documentary film about BBSes,

BBS: The Documentary, and a 2010 documentary film about interactive fiction, GET LAMP.Scott lives in Hopewell Junction, New York. He is the co-owner of twitter celebrity cat Sockington. He works for Internet Archive and has given numerous presentations at technology related conferences on the topics of digital history, software, and website preservation.

Libuv

libuv (Unicorn Velociraptor Library) is a multi-platform C library that provides support for asynchronous I/O based on event loops. It supports epoll(4), kqueue(2), Windows IOCP, and Solaris event ports. It is primarily designed for use in Node.js but it is also used by other software projects. It was originally an abstraction around libev or Microsoft IOCP, as libev supports only select backend and doesn't support poll and IOCP on Windows. In node-v0.9.0's version of libuv, the dependency on libev was removed.

McBBS

McBBS was a Bulletin Board System developed by Derek E. McDonald and distributed by DMCS Technologies between October 30, 1989 and May 30, 2000 and operated over 18 versions.

Remote Imaging Protocol

The Remote Imaging Protocol and its associated Remote Imaging Protocol Scripting Language, RIPscrip, is a scripting language that provides a system for sending vector graphics over low-bandwidth links, notably modems. It was originally created by Jeff Reeder, Jim Bergman, and Mark Hayton of TeleGrafix Communications in Huntington Beach, California to enhance bulletin board systems and other applications.

RIPscrip was introduced in 1992 and consisted of ASCII-text descriptions of vector-drawn graphics and images, along with facilities to create menus and clickable buttons. These were sent from the BBS instead of the more common ANSI color-coded text-mode screens, and were interpreted on the user's end by a RIP-enabled terminal program such as TeleGrafix's own RIPTerm. Lines of text appeared in one display, graphics in another. RIPscrip could not be used as the basis for a complete GUI, as it included no text editing system.

RIPscript 1.5x was, in effect, simply a text based wrapper around the Borland Graphics Interface (BGI). Drawing primitives all relied on the BGI, fonts were limited to those provided by the BGI (*.CHR), and even the RIPscrip icon (.ICN) file format was simply that of the BGI getImage() and putImage() functions. The choice to include the BGI flood fill function was considered by many to be a mistake, as third-party implementations of the RIPscip protocol often failed to implement Bezier curves the same way Telegrafix had, thus leading to the flood fill leaking out of the intended object, and filling the entire screen. Telegrafix never published their Bezier algorithm or a complete RIPscrip specification, thus ensuring developers wishing to implement RIPscrip were forced to purchase Telegrafix's expensive developers kit, containing pre-compiled BGI wrapper DLLs.

Early versions of RIPscrip were tightly tied to the EGA 640×350 EGA standard and had a decidedly MS-DOS-like feel. Later versions provided resolution independence (after a fashion), expanded color palettes, and the ability to work over telnet for Internet access. By this time public access to the World Wide Web caused interest in bulletin board systems to rapidly decline, resulting in the eventual end of RIPscrip development and the company. Although RIPscrip 2.0 was released and 3.0 was planned, the most common version of RIPscrip in actual use was the 1.5x series.

Vector image standards which are present on the World Wide Web today that draw some similarities include Adobe Flash and SVG.

Text-based user interface

Text-based user interface (TUI), also called textual user interface or terminal user interface, is a retronym coined sometime after the invention of graphical user interfaces (GUI). TUIs display computer graphics in text mode. An advanced TUI may, like GUIs, use the entire screen area and accept mouse and other inputs.

VT220

The VT220 is an ANSI standard computer terminal introduced by Digital Equipment Corporation (DEC) in 1983. The VT240 added monochrome ReGIS vector graphics support to the base model, while the VT241 did the same in color. The 200 series replaced the successful VT100 series, providing more functionality in a much smaller unit with a much smaller and lighter keyboard. Among its major upgrades was a number of international character sets, as well as the ability to define new character sets.

The VT200 series was extremely successful in the market. Released at $795, the VT220 offered features, packaging and price that no other serial terminal could touch. In 1986, DEC shipped 165,000 units, giving them a 42% market share, double that of the closest competitor, Wyse. Competitors adapted by introducing similar models at lower price points, leading DEC to do the same by releasing the less-expensive $545 VT300 series in 1987. By that time, DEC had shipped over one million VT220s.

256-color mode — foreground: ESC[38;5;#m   background: ESC[48;5;#m
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