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ANSI Control Sequences

ANSI Control Sequences.

These are used to control things in the terminal, like terminal text color, background colors, cursor visibility, screen clearing, mouse tracking, etc.

They're very useful for customizing how a terminal behaves under certain circumstances.

For colors, see text formatting sequences.

Types of Sequences

There are a few different types of ANSI control sequences:

  1. ESC: Escape Sequences. Start with ESC (e.g., \033, \x1b)
  2. CSI: Control Sequence Introducer. Starts with ESC [, or CSI (\x9B)
  3. DCS: Device Control String. Starts with ESC P, or DSC (\x90)

  4. OSC: Operating System Command. Starts with ESC ], or OSC )\x9D

    • (ignore whitespace between ESC and [ / P / ])

Below is how you'd perform the ANSI control sequences (where \x1b is ESC):

\x1b      # Basic escape sequence
\x1b[     # Control sequence introducer
\x1bP     # Device Control String
\x1b]     # Operating System Command

Also see ANSI escape sequence syntax.

ANSI Escape Sequence Syntax

You can start escape sequences a number of different ways.

These different methods of starting ANSI control sequences are called "Control Sequence Introducer," or "CSI" commands.

  • Standard ANSI escape sequences are prefixed with ESC[, where ESC is one of:
    • \x1b: Hexadecimal for ESC.
    • \033: Octal for ESC.
    • \u001b: Unicode for ESC.
    •  (^[): The actual escape control character.
      • Typing the characters ^ and [ will not work for this. It needs to be the actual Ctrl-[ key signal.
    • \e: Interpreted as ESC by many programs.
      • \e is not guaranteed to work in all languages/compilers.
      • It's recommended to use octal, hexadecimal, or unicode for ESC.
      • Check what's supported in your language/environment. 
\e      # Interpreted as ESC by programs
\033    # ESC in (Octal)
\x1b    # ESC in (Hexadecimal)
\u001b  # ESC in (Unicode)
^[      # ESC (the actual ESC control character, not the ^ and [ characters)

Any ESC on this page can safely be replaced by \033, \x1b, or \u001b.
You can use  or \e (if supported).

The general syntax for an ANSI escape sequence is:

printf "\e[SEQ"
# or
printf "\033[SEQ"
# or
printf "EQ"
# or
printf "\x1b[SEQ"
SEQ is the ANSI sequence that you're trying to access.

Some ANSI control sequences take multiple arguments. Specify multiple arguments by using semicolons (;) in between them.

For example, using a 255-color escape sequence:

"\x1b[38;5;33m"

  • 38: First arg
  • 5: Second arg
  • 33: Third arg
  • m: The end

ASCII Codes

The ASCII codes here are used in some of the ANSI control sequences.

Name Decimal Octal Hex C Escape Ctrl-Key What it is
BEL 7 007 0x07 \a ^G Terminal bell
BS 8 010 0x08 \b ^H Backspace
HT 9 011 0x09 \t ^I Horizontal tab
LF 10 012 0x0A \n ^J Line feed (newline)
VT 11 013 0x0B \v ^K Vertical tab
FF 12 014 0x0C \f ^L Form feed (also: New page NP)
CR 13 015 0x0D \r ^M Carriage return (CR)
ESC 27 033 0x1B \e ^[ Escape character
DEL 127 177 0x7F <none> <none> Delete character

Text Formatting Sequences (SGR)

SGR - Select Graphic Rendition. This is used to format text.

The ANSI color control sequences are used to change the text color
and background color of the terminal.

Each number in the control sequence represents a way to customize the foreground (text) or background.

See the wiki article for a list of SGR parameters.

Color Basic Syntax

The basic syntax for an ANSI color control sequence is: 

printf "\e[<STYLE_CODE>m"
  • \e represents the escape character, which begins the sequence.
  • <STYLE_CODE> is a number (or series of numbers separated by semicolons) that specifies the color or style.
  • m indicates the end of the sequence.

Quickref

Colors:

Number Color
0 black
1 red
2 green
3 yellow
4 blue
5 magenta
6 cyan
7 white

ANSI codes:

Number Description
0 clear
1 bold
4 underline
5 blink
30-37 fg color
40-47 bg color
1K clear line (to beginning of line)
2K clear line (entire line)
2J clear screen
0;0H move cursor to 0;0
1A move up 1 line

Bash Utilities: 

hide_cursor() { printf "\e[?25l"; }
show_cursor() { printf "\e[?25h"; }

Common Style Codes

  • Text Styles and Defaults

    • 0: Reset all styles to default.
    • 1: Bold.
    • 4: Underline.
    • 5: Blink (not widely supported).
    • 7: Inverse (swap foreground and background colors).
    • 39: Default foreground (text) color.
    • 49: Default background color.

  • Standard Text Colors (30-37, 90-97)

    • 30 to 37: Standard foreground colors.
    • 40 to 47: Standard background colors.
    • 90 to 97: Bright (or bold) mode for 16-color foreground colors.
    • 100 to 107: Bright (or bold) mode for 16-color background colors.

  • 256-Color Mode

    • 38;5;<COLOR_CODE>: Set the foreground color in 256-color mode.
    • 48;5;<COLOR_CODE>: Set the background color in 256-color mode.
    • <COLOR_CODE> ranges from 0 to 255.

Standard Colors (8 color)

The foreground (30-37) and background (40-47) colors use 8 "standard" colors.

The 8 standard colors are:

  • 0: Black
  • 1: Red
  • 2: Green
  • 3: Yellow
  • 4: Blue
  • 5: Magenta
  • 6: Cyan
  • 7: White

Formatting the Style Code

The style code can be formatted in several ways. As long as the numbers given match the ones above, the order doesn't matter
all that much.

I generally format the style code like this: 

printf "\e[<TEXT_STYLE>;<COLOR_MODE>;<COLOR>]"

  • <TEXT_STYLE> is a number that specifies the text style (1-7 or 0).
    • There can be multiple text styles, separated by semicolons.
  • <COLOR_MODE> will specify the color mode (i.e., if using 256-color).
    • This can be 38;5 or 48;5 for 256-color mode foreground and background respectively.

ANSI Color Examples

printf "\e[1;5;31;40m---Testing a color code---\e[0m"
  • \e[: The start of the sequence
    • This can also be \033[
  • 1;5;: Specifies bold and blinking text (styles 1-7))
  • 31;: Specifies red text (foreground 30-37)
  • 40: Specifies grey/black background (background 40-47)

  • m: The end of the sequence

  • \e[0m: Resets all styles to default.

256-colors

In an ANSI control sequence using SGR, the control sequence can take multiple arguments to specify 256-color. 

"\x1b[38;5;196m"
  • ESC[: CSI
  • 38;: indicates "foreground"
  • 5;: indicates "256-color"
  • 33: A number in the range 0-255.
  • m: The end of the control sequence. 
SYNTAX="\e[38;5;${COLOR_CODE}m"  
# or, if used in your prompt customization:  
PS1_SYNTAX="\[\e[38;5;${COLOR_CODE}m\]"  

# Boils down to this:
"ESC[38;5;${COLOR_CODE}m"   # Select foreground color
"ESC[48;5;${COLOR_CODE}m"   # Select background color

The ESC is one of the escape methods listed here.

The ${COLOR_CODE} is a number between 0 and 255:

  • 0-7: Standard colors (Same as ESC[30-37m)
  • 8-15: High intensity colors (Same as ESC[90-97m)
  • 16-231: 6x6x6 RGB cube
  • 232-255: Grayscale in 24 steps.

Chaining Colors

You can specify both a foreground and background color in the same escape sequence.
An example: 

printf "\x1b[38;5;196;48;5;227mHello, world\x1b[0m\n"

  • \x1b[: CSI (ESC[)
  • 38;5;196: Specify the foreground (38)
    • 5;196 is selecting 196 out of the 256 colors.
  • 48;5;232: Specify the background (48)
    • 5;232 is selecting 232 out of the 256 colors.

This prints the text Hello, world with a black background with red text.

Then we have \x1b[0m to reset the colors back to their defaults.

Terminal Manipulation Sequences

Cursor Manipulation

These sequences control the cursor's position on the screen.

Sequence Action
ESC[nA Move cursor up by n lines
ESC[nB Move cursor down by n lines
ESC[nC Move cursor forward by n columns
ESC[nD Move cursor backward by n columns
ESC[nF Move cursor to beginning of line, n lines up
ESC[nG Move cursor to column n
ESC[n;fH Move cursor to row n, column f
ESC[M Move cursor one line up. Scrolls if necessary
ESC[6n Request cursor position (responds as ESC[n;nR), (literal n)
ESC[7 Save cursor position (DEC)
ESC[8 Restore cursor position (DEC)
ESC[s Save cursor position (SCO)
ESC[u Restore cursor position (SCO)
  • DEC v. SCO
    • Some terminals (xterm-derived) support both SCO and DEC sequences, but they may have different functionality.
    • Prefer DEC sequences over SCO.

You can also change the cursor's shape and behavior.

Sequence Description
ESC[0 q Changes cursor shape to steady block
ESC[1 q Changes cursor shape to steady block also
ESC[2 q Changes cursor shape to blinking block
ESC[3 q Changes cursor shape to steady underline
ESC[4 q Changes cursor shape to blinking underline
ESC[5 q Changes cursor shape to steady bar
ESC[6 q Changes cursor shape to blinking bar
ESC[?25l Hide the cursor
ESC[?25h Show the cursor (unhide cursor)

E.g.,:

printf "\x1b[\x30 q" # changes to blinking block
printf "\x1b[\x31 q" # changes to blinking block
printf "\x1b[\x32 q" # changes to steady block
printf "\x1b[\x33 q" # changes to blinking underline
printf "\x1b[\x34 q" # changes to steady underline
printf "\x1b[\x35 q" # changes to blinking bar
printf "\x1b[\x36 q" # changes to steady bar

printf "\x1b[?25l"   # will hide cursor
printf "\x1b[?25h"   # will show cursor again

Screen and Line Clearing

These sequences clear parts or all of the terminal screen.

Sequence Action
ESC[J Clear from cursor to end of the screen (same as ESC[0J)
ESC[0J Clear from cursor to end of the screen
ESC[1J Clear from cursor to beginning of the screen
ESC[2J Clear entire screen
ESC[3J Clear saved lines
ESC[K Clear from cursor to end of line (same as ESC[0K)
ESC[0K Clear from cursor to end of line
ESC[1K Clear from cursor to beginning of line
ESC[2K Clear entire line

Clearing lines won't move the cursor. The cursor will stay where it was before clearing. Use \r to move the cursor to the beginning of the line if you need to.
Also see cursor movement.

Mouse Interaction

Some terminals support mouse tracking sequences:

Sequence Action
ESC[?1000h Enable mouse tracking
ESC[?1000l Disable mouse tracking

Operating System Commands (OSC)

These sequences interact with the terminal emulator's operating system features.

Sequence Action
ESC]0;titleBEL Set window title to title
ESC]2;titleBEL Set icon name to title

BEL is the bell character (\a or \x07).

Private Modes

These are implemented in most terminals, though not explicitly defined in the ANSI specification.

Sequence Description
ESC[?25l Make cursor invisible
ESC[?25h Make cursor visible
ESC[?47l Restore screen
ESC[?47h Save screen
ESC[?1049h Enables the alternative buffer
ESC[?1049l Disables the alternative buffer
ESC[?1004h Enable reporting focus. Reports whenever terminal enters/exits focus (ESC[I/ESC[O respectively.
ESC[?1004l Disable reporting focus.
ESC[ s Save current cursor position (SCP, SCOSC).
ESC[ u Restore saved cursor position (RCP, SCORC).

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