ANSI escape code
Encyclopedia
ANSI escape sequences are characters embedded in the text used to control formatting, color, and other output options on video text terminals. Almost all terminal emulator
s designed to show text output from a remote computer, and (except for Microsoft Windows
) to show text output from local software, interpret at least some of the ANSI escape sequences.
had to be created so programs could use the same API
for all of them. In addition, most designs required sending numbers (such as row & 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 first standard for ANSI escape sequences was ECMA
-48, adopted in 1976. It was a continuation of a series of character coding standards, the first one being ECMA-6 from 1961, a 7-bit standard from which ASCII
originates. ECMA-48 has been updated several times and the current edition is the 5th from 1991. It is also adopted by ISO
and IEC
as standard ISO/IEC 6429. The name "ANSI escape sequence" dates from 1981 when ANSI
adopted ECMA-48 as the standard ANSI X3.64 (and later, in 1997, withdrew it).
The first popular video terminal to support these sequences was the Digital VT100
introduced in 1978., which sparked a variety of "clones," among the earliest and most popular of which was the much more affordable Zenith Z19
in 1979. The popularity of these gradually led to more and more software (especially bulletin board system
s) assuming the escape sequences worked, leading to almost all new terminals and emulator programs supporting them.
s running on Unix-like
systems (such as xterm
and the OS X Terminal) interpret ANSI escape sequences. The native text console in Linux
(the text seen when X is not running) also interprets them. Terminal programs for Microsoft Windows
designed to show text from an outside source (a serial port, modem, or socket) also interpret them. Some support for text from local programs on Windows is offered through alternate command processors such as JP Software's 4NT
, Michael J. Mefford's ANSI.COM, and Jason Hood's ansicon.
Many Unix applications (e.g. ls
, grep
, Vim
, and Emacs
) can generate them, and until 2000 or so this was the primary way they produced their display, even if that display was almost always inside a terminal emulator on a graphics display. Utility programs such as tput
output them, as well as in low-level programming libraries, such as termcap
or terminfo
, or a higher-level library such as curses
.
, LF, BS) were interpreted, making it impossible to do any kind of full-screen application. Any display effects had to be done with BIOS calls (or far more often by directly manipulating the IBM PC hardware).
MS-DOS 2.0 introduced the ability to add a device driver
for the ANSI escape sequences – the de facto
standard being
ANSI.SYS and similar drivers continued to work in through Windows 98, and even in Windows Me, when they were set to native DOS mode (the characters taking the whole screen). ANSI.SYS also worked in NT-derived systems for 16-bit legacy programs executing under the NTVDM.
Console windows in all versions of Windows do not support ANSI escape sequences at all. Software can manipulate the console with ioctl
-like Console API interlaced with the text output, for instance:
SetConsoleTextAttribute(ConOut, background|FOREGROUND_RED|FOREGROUND_INTENSITY);
(ASCII
decimal
27/hex
0x1B/octal
033). For two character sequences the second character is in the range ASCII 64 to 95 (@ to _). Most of the sequences are however more than two characters, and start with the characters ESC
and[ (left bracket). This sequence is called CSI for Control Sequence Introducer (or Control Sequence Initiator). The final character of these sequences is in the range ASCII
64 to 126 (@ to ~).
There is a single-character CSI (155/0x
9B/0
233) as well. The ESC+[ two-character sequence is more often used than the single-character alternative, for details see C0 and C1 control codes
. Only the two-character sequence is recognized by devices that support just ASCII
(7-bit bytes) or devices that support 8-bit bytes but use the 0x80–0x9F control character range for other purposes.
On terminals that use UTF-8
encoding, both forms take 2 bytes, but the two-character sequence is more clear.
Though some encodings use multiple byte
s per character, the following discussion is restricted to ASCII characters, and so assumes each character is directly represented by a single-byte.
ESC N = SS2, ESC O = SS3 - select a single character from one of the alternate character sets.
ESC ^ = PM,
ESC _ = APC - these each take a single string of text, terminated by ST (ESC \ ). They are ignored by xterm
ESC P = DCS: Device control string,
ESC ] = OSC: Operating system command - these are similar to CSI, but not limited to integer arguments. Because they are frequently used, in many cases BEL is an acceptable alternative to ST. E.g., in xterm, the window title can be set by: "OSC0;this is the window titleBEL"
Note: 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.
The final byte is technically any character in the range 64 to 126 (hex
0x40 to 0x7e, ASCII @ to ~), and may be modified extended with leading intermediate bytes in the range 32 to 47 (hex 0x20 to 0x2f).
The colon (0x3a) is the only character not a part of the general sequence; it was left for future standardization, so any sequence containing it should be ignored.
Although multiple private mode characters or trailing intermediates are permitted, there are no such known usages.
If there are any leading private mode characters, the main body of the sequence could theoretically contain any order of characters 0x30 – 0x3f instead of a well-formed semicolon-separated list of numbers, but all known terminals are nice and just use them as a flag.
Sequences are also private if the final byte is in the range 112 to 126 (hex 0x70 to 0x7e, ASCII p to ~).
Examples of private escape codes include the DECTCEM (DEC
text cursor enable mode) shown below.
It was first introduced for the VT-300 series of video terminals
.
The existence of a C0 control, DEL (0x7f), or a high characters is undefined. Typically, implementations will either cancel the sequence or execute the control and then continue parsing the CSI sequence.
There are two other color standards CSS/HTML standard colors
and X Window colors
which standardize both the color names and associated RGB color values
, but the escape sequence standard only specifies the color names, not RGB values. The chart below shows default RGB assignments for some common terminal programs, together with the CSS and the X-Window colors for these color names.
The VGA column denotes the typical colors that are used when booting PCs and leaving them in their classical 80×25 text mode. The colors are different in the EGA/VGA graphic modes.
In July 2004 the blue colors of xterm changed, RGB (0,0,205) --> (0,0,238) for normal and (0,0,255) --> (92,92,255) for bright. As of 2010 old xterm versions still linger on many computers though.
and UNIX-like terminals
to provide syntax highlighting
. For example, on compatible terminals, the following list
command colour-codes file and directory names by type.
ls --color=always
Users can employ escape codes in their scripts by including them as part of standard output or standard error. For example, the following sed
command embellishes the output of the make command by displaying lines containing words starting with "ERR" in reverse video, and words starting with "WARN" in bold (letter case
is ignored).
make 2>&1 | sed -e 's/.*\bERR.*/\x1b[7m&\x1b[0m/i' -e 's/.*\bWARN.*/\x1b[1m&\x1b[0m/i'
The representations of the codes are highlighted.
See also
External links
Terminal emulator
A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
s designed to show text output from a remote computer, and (except for Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
) to show text output from local software, interpret at least some of the ANSI escape sequences.
History
Almost all manufacturers of video terminals added vendor-specific escape sequences to do operations such as placing the cursor at arbitrary positions on the screen. As these sequences were all different, elaborate libraries such as termcapTermcap
Termcap is a software library and database used on Unix-like computers. It enables programs to use display computer terminals in a device-independent manner, which greatly simplifies the process of writing portable text mode applications...
had to be created so programs could use the same API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
for all of them. In addition, most designs required sending numbers (such as row & 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 first standard for ANSI escape sequences was ECMA
Ecma International
Ecma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...
-48, adopted in 1976. It was a continuation of a series of character coding standards, the first one being ECMA-6 from 1961, a 7-bit standard from which ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
originates. ECMA-48 has been updated several times and the current edition is the 5th from 1991. It is also adopted by ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
and IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
as standard ISO/IEC 6429. The name "ANSI escape sequence" dates from 1981 when ANSI
American National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
adopted ECMA-48 as the standard ANSI X3.64 (and later, in 1997, withdrew it).
The first popular video terminal to support these sequences was the Digital VT100
VT100
The VT100 is a video terminal that was made by Digital Equipment Corporation . Its detailed attributes became the de facto standard for terminal emulators.-History:...
introduced in 1978., which sparked a variety of "clones," among the earliest and most popular of which was the much more affordable Zenith Z19
Zenith Z89
The Z-89 was a personal computer produced by Zenith Data Systems in the early 1980s. It was based on the Zilog Z80 microprocessor and ran the HDOS and CP/M operating systems...
in 1979. The popularity of these gradually led to more and more software (especially bulletin board system
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
s) assuming the escape sequences worked, leading to almost all new terminals and emulator programs supporting them.
Support
Most terminal emulatorTerminal emulator
A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
s running on Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
systems (such as xterm
Xterm
In computing, xterm is the standard terminal emulator for the X Window System. A user can have many different invocations of xterm running at once on the same display, each of which provides independent input/output for the process running in it .xterm originated prior to the X Window System...
and the OS X Terminal) interpret ANSI escape sequences. The native text console in Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
(the text seen when X is not running) also interprets them. Terminal programs for Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
designed to show text from an outside source (a serial port, modem, or socket) also interpret them. Some support for text from local programs on Windows is offered through alternate command processors such as JP Software's 4NT
4NT
Take Command Console , formerly known as 4DOS for Windows NT and 4NT, is a command line interpreter by JP Software, designed as a substitute for the default command interpreter in Microsoft Windows...
, Michael J. Mefford's ANSI.COM, and Jason Hood's ansicon.
Many Unix applications (e.g. ls
Ls
In computing, ls is a command to list files in Unix and Unix-like operating systems. ls is specified by POSIX and the Single UNIX Specification.- History :An ls utility appeared in the original version of AT&T UNIX...
, grep
Grep
grep is a command-line text-search utility originally written for Unix. The name comes from the ed command g/re/p...
, Vim
Vim (text editor)
Vim is a text editor written by Bram Moolenaar and first released publicly in 1991. Based on the vi editor common to Unix-like systems, Vim is designed for use both from a command line interface and as a standalone application in a graphical user interface...
, and Emacs
Emacs
Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...
) can generate them, and until 2000 or so this was the primary way they produced their display, even if that display was almost always inside a terminal emulator on a graphics display. Utility programs such as tput
Tput
In computing, tput is a standard Unix operating system command which is used to set terminal features.Depending on the system, tput uses the terminfo or termcap database, as well as looking into the environment for the terminal type.-History:...
output them, as well as in low-level programming libraries, such as termcap
Termcap
Termcap is a software library and database used on Unix-like computers. It enables programs to use display computer terminals in a device-independent manner, which greatly simplifies the process of writing portable text mode applications...
or terminfo
Terminfo
Terminfo is a library and database that enables programs to use display terminals in a device-independent manner. This library has its origins in the UNIX System III operating system....
, or a higher-level library such as curses
Curses (programming library)
curses is a terminal control library for Unix-like systems, enabling the construction of text user interface applications.The name is a pun on the term “cursor optimization”. It is a library of functions that manage an application's display on character-cell terminals .- Overview :The curses API...
.
Windows and DOS
MS-DOS 1.0 did not support the ANSI or any other escape sequences. Only a few control characters (CRCarriage return
Carriage return, often shortened to return, refers to a control character or mechanism used to start a new line of text.Originally, the term "carriage return" referred to a mechanism or lever on a typewriter...
, LF, BS) were interpreted, making it impossible to do any kind of full-screen application. Any display effects had to be done with BIOS calls (or far more often by directly manipulating the IBM PC hardware).
MS-DOS 2.0 introduced the ability to add a device driver
Device driver
In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....
for the ANSI escape sequences – the de facto
De facto
De facto is a Latin expression that means "concerning fact." In law, it often means "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established." It is commonly used in contrast to de jure when referring to matters of law, governance, or...
standard being
ANSI.SYSANSI.SYSANSI.SYS is a device driver in the DOS operating system 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 .-Usage:To use ANSI.SYS...
, but others like ANSI.COM, and NANSI.SYS are used as well. Extreme slowness and the fact that it was not installed by default made usage by software almost non-existent; software continued to directly manipulate the hardware to get the text display needed.ANSI.SYS and similar drivers continued to work in through Windows 98, and even in Windows Me, when they were set to native DOS mode (the characters taking the whole screen). ANSI.SYS also worked in NT-derived systems for 16-bit legacy programs executing under the NTVDM.
Console windows in all versions of Windows do not support ANSI escape sequences at all. Software can manipulate the console with ioctl
Ioctl
In computing, ioctl, short for input/output control, is a system call for device-specific operations and other operations which cannot be expressed by regular system calls. It takes a parameter specifying a request code; the effect of a call depends completely on the request code. Request codes are...
-like Console API interlaced with the text output, for instance:
SetConsoleTextAttribute(ConOut, background|FOREGROUND_RED|FOREGROUND_INTENSITY);
Sequence elements
Escape sequences start with the character ESCEscape character
In computing and telecommunication, an escape character is a character which invokes an alternative interpretation on subsequent characters in a character sequence. An escape character is a particular case of metacharacters...
(ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....
27/hex
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
0x1B/octal
Octal
The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. Numerals can be made from binary numerals by grouping consecutive binary digits into groups of three...
033). For two character sequences the second character is in the range ASCII 64 to 95 (@ to _). Most of the sequences are however more than two characters, and start with the characters ESC
Escape character
In computing and telecommunication, an escape character is a character which invokes an alternative interpretation on subsequent characters in a character sequence. An escape character is a particular case of metacharacters...
and
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
64 to 126 (@ to ~).
There is a single-character CSI (155/0x
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
9B/0
Octal
The octal numeral system, or oct for short, is the base-8 number system, and uses the digits 0 to 7. Numerals can be made from binary numerals by grouping consecutive binary digits into groups of three...
233) as well. The ESC+
C0 and C1 control codes
Most character encodings, in addition to representing printable characters, may also 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...
. Only the two-character sequence is recognized by devices that support just ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
(7-bit bytes) or devices that support 8-bit bytes but use the 0x80–0x9F control character range for other purposes.
On terminals that use UTF-8
UTF-8
UTF-8 is a multibyte character encoding for Unicode. Like UTF-16 and UTF-32, UTF-8 can represent every character in the Unicode character set. Unlike them, it is backward-compatible with ASCII and avoids the complications of endianness and byte order marks...
encoding, both forms take 2 bytes, but the two-character sequence is more clear.
Though some encodings use multiple byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
s per character, the following discussion is restricted to ASCII characters, and so assumes each character is directly represented by a single-byte.
Non-CSI codes
Note: other C0 codes besides ESC - commonly BEL, BS, CR, LF, FF, TAB, VT, SO, and SI - may produce similar or identical effects to some control sequences when output.ESC N = SS2, ESC O = SS3 - select a single character from one of the alternate character sets.
ESC ^ = PM,
ESC _ = APC - these each take a single string of text, terminated by ST (ESC \ ). They are ignored by xterm
ESC P = DCS: Device control string,
ESC ] = OSC: Operating system command - these are similar to CSI, but not limited to integer arguments. Because they are frequently used, in many cases BEL is an acceptable alternative to ST. E.g., in xterm, the window title can be set by: "OSC0;this is the window titleBEL"
Note: 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.
CSI codes
The general structure of most ANSI escape sequences isCSI [private mode characters(s?)] n1 ; n2... [trailing intermediate character(s?)] letter. The final byte, modified by private mode characters and trailing intermediate characters, specifies the command. The numbers are optional parameters. The default value used for omitted parameters varies with the command, but 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
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
0x40 to 0x7e, ASCII @ to ~), and may be modified extended with leading intermediate bytes in the range 32 to 47 (hex 0x20 to 0x2f).
The colon (0x3a) is the only character not a part of the general sequence; it was left for future standardization, so any sequence containing it should be ignored.
Although multiple private mode characters or trailing intermediates are permitted, there are no such known usages.
If there are any leading private mode characters, the main body of the sequence could theoretically contain any order of characters 0x30 – 0x3f instead of a well-formed semicolon-separated list of numbers, but all known terminals are nice and just use them as a flag.
Sequences are also private if the final byte is in the range 112 to 126 (hex 0x70 to 0x7e, ASCII p to ~).
Examples of private escape codes include the DECTCEM (DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
text cursor enable mode) shown below.
It was first introduced for the VT-300 series of video terminals
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
.
The existence of a C0 control, DEL (0x7f), or a high characters is undefined. Typically, implementations will either cancel the sequence or execute the control and then continue parsing the CSI sequence.
| 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. |
| CSI n F | CPL – Cursor Previous Line | Moves cursor to beginning of the line n (default 1) lines up. |
| CSI n G | CHA – Cursor Horizontal Absolute | Moves the cursor to column n. |
| 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 Data | 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 – Erase in Line | 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 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) |
| HVP – Horizontal and Vertical Position | Moves the cursor to row n, column m. Both default to 1 if omitted. Same as CUP | |
| SGR – Select Graphic Rendition | Sets SGR parameters, including text color. 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 escape sequences. | |
| CSI 6 n | DSR – Device Status Report | Reports the cursor position to the application as (as though typed at the keyboard) ESC |
| CSI s | SCP – Save Cursor Position | Saves the cursor position. |
| CSI u | RCP – Restore Cursor Position | Restores the cursor position. |
| CSI ?25l | DECTCEM | Hides the cursor. (Note: the trailing character is lowercase L.) |
| CSI ?25h | DECTCEM | Shows the cursor. |
| Code | Effect | Note |
|---|---|---|
| 0 | Reset / Normal | all attributes off |
| 1 | Bright (increased intensity) or Bold | |
| 2 | Faint (decreased intensity) | not widely supported |
| 3 | Italic: on | not widely supported. Sometimes treated as inverse. |
| 4 | Underline: Single | |
| 5 | Blink: Slow | less than 150 per minute |
| 6 | Blink: Rapid | MS-DOS ANSI.SYS; 150 per minute or more; not widely supported |
| 7 | Image: Negative | inverse or reverse; swap foreground and background |
| 8 | Conceal | not widely supported |
| 9 | Crossed-out | Characters legible, but marked for deletion. Not widely supported. |
| 10 | Primary(default) font | |
| 11–19 | n-th alternate font | Select the n-th alternate font. 14 being the fourth alternate font, up to 19 being the 9th alternate font. |
| 20 | Fraktur | hardly ever supported |
| 21 | Bright/Bold: off or Underline: Double | bold off not widely supported, double underline hardly ever |
| 22 | Normal color or intensity | neither bright, bold nor faint |
| 23 | Not italic, not Fraktur | |
| 24 | Underline: None | not singly or doubly underlined |
| 25 | Blink: off | |
| 26 | Reserved | |
| 27 | Image: Positive | |
| 28 | Reveal | conceal off |
| 29 | Not crossed out | |
| 30–37 | Set text color | 30 + x, where x is from the color table below |
| 38 | Set xterm-256 text color | next arguments are 5;x where x is color index (0..255) |
| 39 | Default text color | implementation defined (according to standard) |
| 40–47 | Set background color | 40 + x, where x is from the color table below |
| 48 | Set xterm-256 background color | next arguments are 5;x where x is color index (0..255) |
| 49 | Default background color | implementation defined (according to standard) |
| 50 | Reserved | |
| 51 | Framed | |
| 52 | Encircled | |
| 53 | Overlined | |
| 54 | Not framed or encircled | |
| 55 | Not overlined | |
| 56–59 | Reserved | |
| 60 | ideogram underline or right side line | hardly ever supported |
| 61 | ideogram double underline or double line on the right side | hardly ever supported |
| 62 | ideogram overline or left side line | hardly ever supported |
| 63 | ideogram double overline or double line on the left side | hardly ever supported |
| 64 | ideogram stress marking | hardly ever supported |
| 90–99 | Set foreground color, high intensity | aixterm (not in standard) |
| 100–109 | Set background color, high intensity | aixterm (not in standard) |
Colors
Text color is manipulated using sequence.| Intensity | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|---|
| Normal | Black | Red | Green | Yellow | Blue | Magenta | Cyan | White |
| Bright | Black | Red | Green | Yellow | Blue | Magenta | Cyan | White |
There are two other color standards CSS/HTML standard colors
Web colors
Web colors are colors used in designing web pages, and the methods for describing and specifying those colors. Hexadecimal color codes begin with a hash ....
and X Window colors
X11 color names
In computing, on the X Window System, X11 color names are represented in a simple text file, which maps certain strings to RGB color values. It is shipped with every X11 installation, hence the name, and is usually located in <X11root>/lib/X11/rgb.txt.It is not known who originally compiled...
which standardize both the color names and associated RGB color values
RGB color model
The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors...
, but the escape sequence standard only specifies the color names, not RGB values. The chart below shows default RGB assignments for some common terminal programs, together with the CSS and the X-Window colors for these color names.
| Standard VGA colors | Windows XP command prompt Command Prompt Command Prompt is the Microsoft-supplied command-line interpreter on OS/2, Windows CE and on Windows NT-based operating systems... |
Terminal.app | PuTTY PuTTY PuTTY is a free and open source terminal emulator application which can act as a client for the SSH, Telnet, rlogin, and raw TCP computing protocols and as a serial console client... |
xterm Xterm In computing, xterm is the standard terminal emulator for the X Window System. A user can have many different invocations of xterm running at once on the same display, each of which provides independent input/output for the process running in it .xterm originated prior to the X Window System... |
CSS CSS -Computing:*Cascading Style Sheets, a language used to describe the style of document presentations in web development*Central Structure Store in the PHIGS 3D API*Closed source software, software that is not distributed with source code... /HTML HTML HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages.... |
X Window X Window System The X window system is a computer software system and network protocol that provides a basis for graphical user interfaces and rich input device capability for networked computers... |
||
|---|---|---|---|---|---|---|---|---|
| normal | black | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 | 0, 0, 0 |
| red | 170, 0, 0 | 128, 0, 0 | 194, 54, 33 | 187, 0, 0 | 205, 0, 0 | 255, 0, 0 | 255, 0, 0 | |
| green | 0, 170, 0 | 0, 128, 0 | 37, 188, 36 | 0, 187, 0 | 0, 205, 0 | 0, 255, 0 | 0, 128, 0 | |
| brown/yellow | 170, 85, 0 | 128, 128, 0 | 173, 173, 39 | 187, 187, 0 | 205, 205, 0 | 255, 255, 0 | 255, 255, 0 | |
| blue | 0, 0, 170 | 0, 0, 128 | 73, 46, 225 | 0, 0, 187 | 0, 0, 238 | 0, 0, 255 | 0, 0, 255 | |
| magenta | 170, 0, 170 | 128, 0, 128 | 211, 56, 211 | 187, 0, 187 | 205, 0, 205 | 255, 0, 255 | 255, 0, 255 | |
| cyan | 0, 170, 170 | 0, 128, 128 | 51, 187, 200 | 0, 187, 187 | 0, 205, 205 | 0, 255, 255 | 0, 255, 255 | |
| gray | 170, 170, 170 | 192, 192, 192 | 203, 204, 205 | 187, 187, 187 | 229, 229, 229 | 255, 255, 255 | 255, 255, 255 | |
| bright/light | darkgray | 85, 85, 85 | 128, 128, 128 | 129, 131, 131 | 85, 85, 85 | 127, 127, 127 | ||
| red | 255, 85, 85 | 255, 0, 0 | 252,57,31 | 255, 85, 85 | 255, 0, 0 | |||
| green | 85, 255, 85 | 0, 255, 0 | 49, 231, 34 | 85, 255, 85 | 0, 255, 0 | 144, 238, 144 | 144, 238, 144 | |
| yellow | 255, 255, 85 | 255, 255, 0 | 234, 236, 35 | 255, 255, 85 | 255, 255, 0 | 255, 255, 224 | 225, 255, 224 | |
| blue | 85, 85, 255 | 0, 0, 255 | 88, 51, 255 | 85, 85, 255 | 92, 92, 255 | 173, 216, 230 | 173, 216, 230 | |
| magenta | 255, 85, 255 | 255, 0, 255 | 249, 53, 248 | 255, 85, 255 | 255, 0, 255 | |||
| cyan | 85, 255, 255 | 0, 255, 255 | 20, 240, 240 | 85, 255, 255 | 0, 255, 255 | 224, 255, 255 | 224, 255, 255 | |
| white | 255, 255, 255 | 255, 255, 255 | 233, 235, 235 | 255, 255, 255 | 255, 255, 255 |
The VGA column denotes the typical colors that are used when booting PCs and leaving them in their classical 80×25 text mode. The colors are different in the EGA/VGA graphic modes.
In July 2004 the blue colors of xterm changed, RGB (0,0,205) --> (0,0,238) for normal and (0,0,255) --> (92,92,255) for bright. As of 2010 old xterm versions still linger on many computers though.
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. On MS-DOS, normally the green would be 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. 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 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 UNIXUnix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
and UNIX-like terminals
Virtual console
A virtual console – also known as a virtual terminal – is a conceptual combination of the keyboard and display for a computer user interface. It is a feature of some operating systems such as UnixWare, Linux, and BSD, in which the system console of the computer can be used to switch between...
to provide syntax highlighting
Syntax highlighting
Syntax highlighting is a feature of some text editors that display text—especially source code—in different colors and fonts according to the category of terms. This feature eases writing in a structured language such as a programming language or a markup language as both structures and...
. For example, on compatible terminals, the following list
Ls
In computing, ls is a command to list files in Unix and Unix-like operating systems. ls is specified by POSIX and the Single UNIX Specification.- History :An ls utility appeared in the original version of AT&T UNIX...
command colour-codes file and directory names by type.
ls --color=always
Users can employ escape codes in their scripts by including them as part of standard output or standard error. For example, the following sed
Sed
sed is a Unix utility that parses text and implements a programming language which can apply transformations to such text. It reads input line by line , applying the operation which has been specified via the command line , and then outputs the line. It was developed from 1973 to 1974 as a Unix...
command embellishes the output of the make command by displaying lines containing words starting with "ERR" in reverse video, and words starting with "WARN" in bold (letter case
Letter case
In orthography and typography, letter case is the distinction between the larger majuscule and smaller minuscule letters...
is ignored).
make 2>&1 | sed -e 's/.*\bERR.*/\x1b[7m&\x1b[0m/i' -e 's/.*\bWARN.*/\x1b[1m&\x1b[0m/i'
The representations of the codes are highlighted.
Illegal and ambiguous sequences in use
- The Linux console uses
OSC P n rr gg bbto change the palette, which, if hard-coded into an application, may hang other terminals. However, appendingSTwill 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 TerminatorTerminator (terminal emulator)Terminator is a GPL terminal emulator. It is available on Microsoft Windows, Mac OS X, Linux and other Unix X11 systems. Terminator will run on any modern POSIX system with Java 5 or later....
generatesSS3 1; modifiers charwhen F1–F4 are pressed with modifiers. The faulty behavior was copied from GNOME TerminalGNOME TerminalGNOME Terminal is a terminal emulator for the GNOME desktop environment written by Havoc Pennington and others. Terminal emulators allow users to execute commands using a real UNIX shell while remaining on their graphical desktop.-Features:...
. - xterm replies
CSI row ; column Rif asked for cursor position andCSI 1 ; modifiers Rif 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
ESCto any character that is typed with the alt key down. This creates ambiguity for uppercase letters and symbols @[\]^_, which would form C1 codes. - KonsoleKonsoleKonsole is a free terminal emulator which is part of KDE Software Compilation. Konsole was originally written by Lars Doelle.The KDE applications Konqueror, Krusader, Kate, Konversation, Dolphin and KDevelop use Konsole to provide embedded terminal functionality.- Features :* Tabbed terminals...
generatesSS3 modifiers charwhen F1–F4 are pressed with modifiers.
See also
- ANSI artANSI artANSI 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...
- Control characterControl characterIn computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
- Advanced Video Attribute Terminal Assembler and Recreator (AVATAR)
External links
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...
Control character
In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
- Standard ECMA-48, Control Functions For Coded Character Sets. (5th edition, June 1991), European Computer Manufacturers Association, Geneva 1991 (also published by ISO and IEC as standard ISO/IEC 6429)
- vt100.net DEC Documents
- ANSI.SYS -- ansi terminal emulation escape sequences
- Xterm / Escape Sequences
- AIXterm / Escape Sequences
- A collection of escape sequences for terminals that are vaguely compliant with ECMA-48 and friends.
- ANSI Escape Sequences