Most of these escape sequences start with the characters ESC (ASCII decimal 27/hex 0x1B/octal 033) and [ (left bracket). This sequence is called CSI for Control Sequence Introducer (or Control Sequence Initiator). There is a single-character CSI (155/0x9B/0233) as well. The ESC+[ two-character sequence is more often used than the single-character alternative, for details see C0 and C1 control codes. Devices supporting only ASCII (7-bits), or which implement 8-bit code pages which use the 0x80–0x9F control character range for other purposes will recognize only the two-character sequence. Though some encodings use multiple bytes per character, in this topic all characters are single-byte.
ANSI.SYS, but others are used as well. Console windows in Windows versions based on NT (Windows NT 4.0, Windows 2000, Windows XP, Windows Server 2003, Windows Vista and Windows Server 2008) do not natively support ANSI Escape sequences, though some support is possible. By adding the following line to the CONFIG.NT file located in the Windows System32 directory, ANSI output from 16-bit legacy programs executing under the NTVDM will be interpreted:
Some support is also offered through alternate command processors such as JP Software's 4NT and Michael J. Mefford's ANSI.COM.
If ANSI.SYS is loaded in MS-DOS, the escape character can be specified as
$e in the prompt command, e.g.
prompt $e[44m;... would specify a blue background as part of the prompt. In most modern programming languages it can be specified as
"x1B" (Perl and Ruby also offer the equivalent
"e"), in Java it can be specified as
"u001B", and in BASIC it can be specified as
32-bit character-mode (subsystem:console) Windows applications don't write ANSI escape sequences to the console. They must interpret the escape code actions and call the native Console API instead to accomplish the proper result. If you do write the sequences directly, all you'll get is the text of the sequence on the screen, not the action intended. To add ANSI support, one must parse the string for ANSI escape codes and apply the actions oneself using the Console API. For example, if you pull out e[1;31m from your text stream on the way to a Console for display, you'd read that to mean change the foreground color to bright red and do so with something like this:
foreground = FOREGROUND_RED|FOREGROUND_INTENSITY;
The Windows hardware abstraction layer does not permit user-mode applications to set the underlying VGA registers The Window's Console API has some restrictions regarding the blink, underline and reverse VGA attributes.
Note: most devices only support a subset of the SGR (Select Graphic Rendition) codes.
CSI n1 ; n2... letter. The numbers are optional parameters, and the final byte specifies the command. The default value used for omitted parameters varies with the command; it is usually 1 or 0. If trailing parameters are omitted, the trailing semicolons may also be omitted.
The final byte is technically any character in the range 64 to 126 (hex 0x40 to 0x7e, ASCII @ to ~), and may be extended with leading intermediate bytes in the range 32 to 47 (hex 0x20 to 0x2f). Only the case of a single intermediate byte of 32 is currently standardized.
Some of the ANSI codes are private (not covered by the standard). There are two ways these are encoded:
|CSI n A||CUU|| 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.|
CUU: Up; CUD: Down; CUF: Forward; CUB: Back;
|CSI n B||CUD|
|CSI n C||CUF|
|CSI n D||CUB|
|CSI n E||CNL||Moves cursor to beginning of the line n (default 1) lines down (next line).|
|CSI n F||CPL||Moves cursor to beginning of the line n (default 1) lines up (previous line).|
|CSI n G||CHA||Moves the cursor to column n.|
|CUP||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||Clears part of the screen. If n is zero (or missing), clear from cursor to end of screen. If n is one, clear from cursor to beginning of the screen. If n is two, clear entire screen (and moves cursor to upper left on MS-DOS ANSI.SYS).|
|CSI n K||EL||Erases part of the line. If n is zero (or missing), clear from cursor to the end of the line. If n is one, clear from cursor to beginning of the line. If n is two, clear entire line. Cursor position does not change.|
|CSI n S||SU||Scroll whole page up by n (default 1) lines. New lines are added at the bottom. (not ANSI.SYS)|
|CSI n T||SD||Scroll whole page down by n (default 1) lines. New lines are added at the top. (not ANSI.SYS)|
|HVP||Moves the cursor to row n, column m. Both default to 1 if omitted. Same as CUP|
|SGR||Sets SGR (Select Graphic Rendition) parameters. After CSI can be zero or more parameters separated with ;. With no parameters, CSI m is treated as CSI 0 m (reset / normal), which is typical of most of the ANSI codes.|
|CSI 6 n||DSR||Reports the cursor position to the application as (as though typed at the keyboard) ESC[n;mR, where n is the row and m is the column. (May not work on MS-DOS.)|
|CSI s||SCP||Saves the cursor position.|
|CSI u||RCP||Restores the cursor position.|
|CSI ?25l||DECTCEM||Hides the cursor.|
|CSI ?25h||DECTCEM||Shows the cursor.|
|0||Reset / Normal||all attributes off|
|2||Intensity: Faint||not widely supported|
|3||Italic: on||not widely supported. Sometimes treated as inverse.|
|4||Underline: Single||not widely supported|
|5||Blink: Slow||less than 150 per minute|
|6||Blink: Rapid||MS-DOS ANSI.SYS; 150 per minute or more|
|7||Image: Negative||inverse or reverse; swap foreground and background|
|8||Conceal||not widely supported|
|22||Intensity: Normal||not bold and not faint|
|30–39||Set foreground color, normal intensity||3x, where x is from the color table above|
|40–49||Set background color, normal intensity||4x, where x is from the color table above|
|90–99||Set foreground color, high intensity||aixterm|
|100–109||set background color, high intensity||aixterm|
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. On MS-DOS, normally the green would be dark, dull green, so you may wish to enable Bold with the code
CSI 1 m which would make it bright green, or combined as
CSI 32 ; 1 m. MS-DOS ANSI.SYS uses the Bold state to make the character Bright; also the Blink state can be set (via
INT 10, AX 1003h, BL 00h) to render the Background in the Bright mode. MS-DOS ANSI.SYS does not support SGR codes 90–97 and 100–107 directly.
CSI 0 ; 6 8 ; "DIR" ; 13 p — This re-assigns 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 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 code
CSI u will restore it to the position. Say the current cursor position is 7(y) and 10(x). The code
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 code
CSI 20 ; 3 H or
CSI 20 ; 3 f. Now if you use the code CSI u the cursor position will return to 7(y) and 10(x). Some terminals require the DEC sequences
ESC 7 /
ESC 8 instead.