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wezterm/docs/escape-sequences.md

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Please note that this is a "living document" and may lag or lead the state of the current stable release in a number of areas--as you might imagine, precisely documenting escape codes and their behaviors and cross-checking with the various technical documents is laborious and tedious and I only have so much spare time!

If you notice that something is inaccurate or missing, please do file an issue so that it can be resolved!

Output/Escape Sequences

WezTerm considers the output from the terminal to be a UTF-8 encoded stream of codepoints. No other encoding is supported. As described below, some C1 control codes have both 7-bit ASCII compatible as well as 8-bit representations. As ASCII is a compatible subset of UTF-8, the 7-bit representations are preferred and processed without any special consideration.

The 8-bit values are recognized, but only if the 8-bit value is treated as a unicode code point and encoded via a UTF-8 multi-byte sequence.

Printable Codepoints

Codepoints with value 0x20 and higher are considered to be printable and are applied to the terminal display using the following rules:

  • Codepoints are buffered until a C0, C1 or other escape/control sequence is encountered, which triggers a flush and processing continues with the next step.
  • The buffered codepoint sequence is split into unicode graphemes, which means that combining sequences and emoji are decoded. Processing continues for below for each individually recognized grapheme.
  • If DEC line drawing mode is active, graphemes j-n, q, t-x are translated to equivalent line drawing graphemes and processing continues.
  • If prior output/actions require it, the cursor position may be moved to a new line and the terminal display may be scrolled to make accomodate it.
  • An appropriate number of cells, starting at the current cursor position, are allocated based on the column width of the current grapheme and are assigned to the grapheme. The current current graphics rendition state (such as colors and other presentation attributes) is also applied to those cells. If insert mode is active, those cells will be inserted at the current cursor position, otherwise they will overwrite cells at the current cursor position.
  • The cursor position will be updated based on the column width of the grapheme.

After the graphemes are applied to the terminal display, the rendering portion of WezTerm will attempt to apply your font shaping configuration based on runs of graphemes with matching graphic attributes to determine which glyphs should be rendered from your fonts; it is at this stage that emoji and ligatures are resolved.

C0 Control Codes

Codepoints in the range 0x00-0x1F are considered to be C0 control codes. C0 controls will flush any buffered printable codepoints before triggering the action described below.

Seq Hex Name Description Action
^@ 0x00 NUL Null Ignored
^A 0x01 SOH Start of Heading Ignored
^B 0x02 STX Start of Text Ignored
^C 0x03 ETX End of Text Ignored
^D 0x04 EOT End of Transmission Ignored
^E 0x05 ENQ Enquiry Ignored
^F 0x06 ACK Acknowledge Ignored
^G 0x07 BEL Bell Logs Ding! (this is the bell) to stderr of the WezTerm process. See #3
^H 0x08 BS Backspace Move cursor left by 1, constrained by the left margin. If Reverse Wraparound and dec auto wrap modes are enabled, moving left of the left margin will jump the cursor to the right margin, jumping to bottom right margin if it was at the top left.
^I 0x09 HT Horizontal Tab Move cursor right to the next tab stop
^J 0x0A LF Line Feed If cursor is at the bottom margin, scroll the region up, otherwise move cursor down 1 row
^K 0x0B VT Vertical Tab Treated as Line Feed
^L 0x0C FF Form Feed Treated as Line Feed
^M 0x0D CR Carriage Return If cursor is left of leftmost margin, move to column 0. Otherwise move to left margin
^N 0x0E SO Shift Out Ignored
^O 0x0F SI Shift In Ignored
^P 0x10 DLE Data Link Escape Ignored
^Q 0x11 DC1 Device Control One Ignored
^R 0x12 DC2 Device Control Two Ignored
^S 0x13 DC3 Device Control Three Ignored
^T 0x14 DC4 Device Control Four Ignored
^U 0x15 NAK Negative Acknowledge Ignored
^V 0x16 SYN Synchronous Idle Ignored
^W 0x17 ETB End Transmission Block Ignored
^X 0x18 CAN Cancel Ignored
^Y 0x19 EM End of Medium Ignored
^Z 0x1A SUB Substitute Ignored
^[ 0x1B ESC Escape Introduces various escape sequences described below
^\|0x1C FS File Separator Ignored
^] 0x1D GS Group Separator Ignored
^^ 0x1E RS Record Separator Ignored
^_ 0x1F US Unit Separator Ignored

C1 Control Codes

As mentioned above, WezTerm only supports UTF-8 encoding. C1 control codes have an 8-bit representation as well as a multi-codepoint 7-bit escape sequence.

The 8-bit representation is recognized if the 8-bit value is treated as a unicode code point and encoded as a multi-byte UTF-8 sequence. Sending the 8-bit binary value will not be recognized as intended, as those bitsequences are passing through a UTF-8 decoder.

The table below lists the 7-bit C1 sequence (which is preferred) as well as the codepoint value, along with the corresponding meaning.

As with C0 control codes, C1 controls will flush any buffered printable codepoints before triggering the action described below.

Seq Codepoint Name Description Action
ESC D 0x84 IND Index Moves the cursor down one line in the same column. If the cursor is at the bottom margin, the page scrolls up
ESC E 0x85 NEL Next Line Moves the cursor to the left margin on the next line. If the cursor is at the bottom margin, scroll the page up
ESC H 0x88 HTS Horizontal Tab Set Sets a horizontal tab stop at the column where the cursor is
ESC M 0x8D RI Reverse Index Move the cursor up one line. If the cursor is at the top margin, scroll the region down
ESC P 0x90 DCS Device Control String Discussed below
ESC [ 0x9B CSI Control Sequence Introducer Discussed below
ESC \|0x9C ST String Terminator No direct effect; ST is used to delimit the end of OSC style escape sequences

Other Escape Sequences

As these sequences start with an ESC, which is a C0 control, these will flush any buffered printable codepoints before triggering the associated action.

Seq Name Description Action
ESC c RIS Reset to Initial State Resets tab stops, margins, modes, graphic rendition, palette, activates primary screen, erases the display and moves cursor to home position
ESC 7 DECSC Save Cursor Position Records cursor position
ESC 8 DECRC Restored Saved Cursor Position Moves cursor to location it had when DECSC was used
ESC = DECPAM Application Keypad Enable Application Keypad Mode
ESC > DECPNM Normal Keypad Set Normal Keypad Mode
ESC (0 DEC Line Drawing character set Translate characters j-x to line drawing glyphs
ESC (B US ASCII character set Disables DEC Line Drawing character translation
ESC #8 DECALN Screen Alignment Display Fills the display with E characters for diagnostic/test purposes (for vttest)

CSI - Control Sequence Introducer Sequences

CSI sequences begin with the C1 CSI sequence, which is either the 7-bit ESC [ sequence or the codepoint 0x9B.

WezTerm classifies these sequences into a number of functional families which are broken out below.

Graphic Rendition (SGR)

SGR sequences are of the form CSI DIGITS [; DIGITS ]+ m. That is, any number of semicolon separated numbers, terminated by the m codepoint. There are a handful of slightly more modern sequences that use colon : codepoints to encode additional context.

The digits map to one of the codes in the table below, which manipulate the presentation attributes of subsequently printed characters.

It is valid to omit the code number; for example CSI m is equivalent to CSI 0 m which resets the presentation attributes.

Code Description Action
0 Reset Reset to default foreground/background colors, reset all presentation attributes, clear any explicit hyperlinks
1 IntensityBold Set the intensity level to Bold. This causes subsequent text to be rendered in a bold font variant and, if the foreground color is set to a palette index in the 0-7 range, effectively shifts it to the brighter value in the 8-15 range
2 IntensityDim Set the intensity level to Dim or Half-Bright. This causes text to be rendered in a lighter weight font variant
3 ItalicOn Sets the italic attribute on the text, causing an italic font variant to be selected
4 UnderlineOn Text will have a single underline
4:0 UnderlineOff Text will have no underline
4:1 UnderlineOn Text will have a single underline
4:2 UnderlineDouble Text will be rendered with double underline
4:3 UnderlineCurly Text will be rendered with a curly underline
4:4 UnderlineDotted Text will be rendered with a dotted underline
4:5 UnderlineDashed Text will be rendered with a dashed underline
5 BlinkOn Indicates that the text should blink <150 times per minute
6 RapidBlinkOn Indicates that the text should blink >150 times per minute
7 InverseOn Causes the foreground and background colors to be swapped
8 InvisibleOn Marks text as invisible.
9 StrikeThroughOn Text will be rendered with a single line struck through the middle
21 UnderlineDouble Text will be rendered with double underline
22 NormalIntensity Cancels the effect of IntensityBold and IntensityDim, returning the text to normal intensity
23 ItalicOff Cancels the effect of ItalicOn
24 UnderlineOff Text will have no underline
25 BlinkOff Cancels the effect of BlinkOn and RapidBlinkOn
27 InverseOff Cancels the effect of InverseOn
28 InvisibleOff cancels the effect of InvisibleOn
29 StrikeThroughOff Cancels the effect of StrikeThroughOn
30 ForegroundBlack Sets the foreground color to ANSI Black, which is palette index 0
31 ForegroundRed Sets the foreground color to ANSI Red, which is palette index 1
32 ForegroundGreen Sets the foreground color to ANSI Green, which is palette index 2
33 ForegroundYellow Sets the foreground color to ANSI Yellow, which is palette index 3
34 ForegroundBlue Sets the foreground color to ANSI Blue, which is palette index 4
35 ForegroundMagenta Sets the foreground color to ANSI Magenta, which is palette index 5
36 ForegroundCyan Sets the foreground color to ANSI Cyan, which is palette index 6
37 ForegroundWhite Sets the foreground color to ANSI White, which is palette index 7
39 ForegroundDefault Sets the foreground color to the user's configured default text color
40 BackgroundBlack Sets the background color to ANSI Black, which is palette index 0
41 BackgroundRed Sets the background color to ANSI Red, which is palette index 1
42 BackgroundGreen Sets the background color to ANSI Green, which is palette index 2
43 BackgroundYellow Sets the background color to ANSI Yellow, which is palette index 3
44 BackgroundBlue Sets the background color to ANSI Blue, which is palette index 4
45 BackgroundMagenta Sets the background color to ANSI Magenta, which is palette index 5
46 BackgroundCyan Sets the background color to ANSI Cyan, which is palette index 6
47 BackgroundWhite Sets the background color to ANSI White, which is palette index 7
49 BackgroundDefault Sets the background color to the user's configured default background color
53 OverlineOn Renders text with a single overline/overbar
55 OverlineOff Cancels OverlineOn
59 UnderlineColorDefault Resets the underline color to default, which is to match the foreground color
90 ForegroundBrightBlack Sets the foreground color to Bright Black, which is palette index 8
91 ForegroundBrightRed Sets the foreground color to Bright Red, which is palette index 9
92 ForegroundBrightGreen Sets the foreground color to Bright Green, which is palette index 10
93 ForegroundBrightYellow Sets the foreground color to Bright Yellow, which is palette index 11
94 ForegroundBrightBlue Sets the foreground color to Bright Blue, which is palette index 12
95 ForegroundBrightMagenta Sets the foreground color to Bright Magenta, which is palette index 13
96 ForegroundBrightCyan Sets the foreground color to Bright Cyan, which is palette index 14
97 ForegroundBrightWhite Sets the foreground color to Bright White, which is palette index 15
100 BackgroundBrightBlack Sets the background color to Bright Black, which is palette index 8
101 BackgroundBrightRed Sets the background color to Bright Red, which is palette index 9
102 BackgroundBrightGreen Sets the background color to Bright Green, which is palette index 10
103 BackgroundBrightYellow Sets the background color to Bright Yellow, which is palette index 11
104 BackgroundBrightBlue Sets the background color to Bright Blue, which is palette index 12
105 BackgroundBrightMagenta Sets the background color to Bright Magenta, which is palette index 13
106 BackgroundBrightCyan Sets the background color to Bright Cyan, which is palette index 14
107 BackgroundBrightWhite Sets the background color to Bright White, which is palette index 15

There are a handful of additional SGR codes that allow setting extended colors; unlike the codes above, which are activated by a single numeric parameter out of SGR sequence, these the extended color codes require multiple parameters. The canonical representation of these sequences is to have the multiple parameters be separated by colons (:), but for compatibility reasons WezTerm also accepts an ambiguous semicolon (;) separated variation. The colon form is unambiguous and should be preferred; the semicolon form should not be used by new applications and is not documented here in the interest of avoiding accidental new implementations.

This sequence will set the foreground color to the specified palette INDEX, which can be a decimal number in the range 0-255.

CSI 38 : 5 : INDEX m

This sequence will set the background color to the specified palette INDEX, which can be a decimal number in the range 0-255.

CSI 48 : 5 : INDEX m

This sequence will set the underline color to the specified palette INDEX, which can be a decimal number in the range 0-255.

CSI 58 : 5 : INDEX m

This sequence will set the foreground color to an arbitrary color in RGB colorspace. The R, G and B symbols below are decimal numbers in the range 0-255. Note that after the 2 parameter two colons are present; its really an omitted colorspace ID parameter but that nature of that parameter is not specified in the accompanying ITU T.416 specification and is ignored by WezTerm and most (all?) other terminal emulators:

CSI 38 : 2 : : R : G : B m

(Since 20210814-124438-54e29167) For the sake of compatibility with some other terminal emulators this additional form is also supported where the colorspace ID argument is not specified:

CSI 38 : 2 : R : G : B m

This sequence will set the background color to an arbitrary color in RGB colorspace. The R, G and B symbols below are decimal numbers in the range 0-255:

CSI 48 : 2 : : R : G : B m

(Since 20210814-124438-54e29167) For the sake of compatibility with some other terminal emulators this additional form is also supported where the colorspace ID argument is not specified:

CSI 48 : 2 : R : G : B m

This sequence will set the underline color to an arbitrary color in RGB colorspace. The R, G and B symbols below are decimal numbers in the range 0-255:

CSI 58 : 2 : : R : G : B m

(Since 20210814-124438-54e29167) For the sake of compatibility with some other terminal emulators this additional form is also supported where the colorspace ID argument is not specified:

CSI 58 : 2 : R : G : B m

Cursor Movement

Editing Functions

Mode Functions

Since: 20210814-124438-54e29167

WezTerm supports Synchronized Rendering. DECSET 2026 is set to batch (hold) rendering until DECSET 2026 is reset to flush the queued screen data.

Device Functions

Window Functions

DCS - Device Control String

The C1 DCS escape places the terminal parser into a device control mode until the C1 ST is encountered.

In the table below, DCS can be either the 7-bit representation (ESC P) or the 8-bit codepoint (0x90).

Seq Name Description
DCS $ q " p ST DECRQSS for DECSCL Request Conformance Level; Reports the conformance level
DCS $ q r ST DECRQSS for DECSTBM Request top and bottom margin report; Reports the margins
DCS $ q s ST DECRQSS for DECSLRM Request left and right margin report; Reports the margins
DCS [PARAMS] q [DATA] ST Sixel Graphic Data Decodes Sixel graphic data and apply the image to the terminal model. Support is preliminary and incomplete; see this issue for status.
DCS 1000 q tmux control mode Bridges tmux into the WezTerm multiplexer. Currently incomplete, see this issue for status.

Operating System Command Sequences

Operating System Command (OSC) sequences are introduced via ESC ] followed by a numeric code and typically have parameters delimited by ;. OSC sequences are canonically delimited by the ST (String Terminator) sequence, but WezTerm also accepts delimiting them with the BEL control.

The table below is keyed by the OSC code.

OSC Description Action Example
0 Set Icon Name and Window Title Clears Icon Name, sets Window Title. \x1b]0;title\x1b\\
1 Set Icon Name Sets Icon Name, which is used as the Tab title when it is non-empty \x1b]1;tab-title\x1b\\
2 Set Window Title Set Window Title \x1b]2;window-title\x1b\\
3 Set X11 Window Property Ignored
4 Change/Query Color Number Set or query color palette entries 0-255. query color number 1: \x1b]4;1;?\x1b\\
Set color number 2: \x1b]4;2;#cccccc\x1b\\
5 Change/Query Special Color Number Ignored
6 iTerm2 Change Title Tab Color Ignored
7 Set Current Working Directory See Shell Integration
8 Set Hyperlink See Explicit Hyperlinks
9 iTerm2 Show System Notification Show a "toast" notification printf "\e]9;%s\e\\" "hello there"
52 Manipulate clipboard Requests to query the clipboard are ignored. Allows setting or clearing the clipboard
104 ResetColors Reset color palette entries to their default values
133 FinalTerm semantic escapes Informs the terminal about Input, Output and Prompt regions on the display See Shell Integration
777 Call rxvt extension Only the notify extension is supported; it shows a "toast" notification printf "\e]777;notify;%s;%s\e\\" "title" "body"
1337 iTerm2 File Upload Protocol Allows displaying images inline See iTerm Image Protocol
L Set Icon Name (Sun) Same as OSC 1 \x1b]Ltab-title\x1b\\
l Set Window Title (Sun) Same as OSC 2 \x1b]lwindow-title\x1b\\

Additional Resources