# Text Foreground Color (OSC 10)

> Set, query and reset the default foreground color.

- **Sequence:** `OSC 10 ; Pt ST`
- **ECMA-48:** [§8.3.89 OSC – Operating System Command, p. 51](https://archive.org/details/ecma-48-5th-edition-june-1991/page/n64/mode/1up)
- **xterm:** [Operating System Commands](https://invisible-island.net/xterm/ctlseqs/ctlseqs.html)

`OSC 10 ; Pt ST` sets the default foreground, the color of text that has no
[SGR](https://control-codes.page/csi/sgr/index.html.md) color of its own, and `OSC 10 ; ? ST` asks what it is.
[OSC 110](https://control-codes.page/osc/reset-foreground/index.html.md) puts it back as it started.

It is the first of xterm's ten *dynamic* colors, each with its own OSC number,
apart from the 256 colors of the [palette](https://control-codes.page/osc/palette/index.html.md):

| `Ps` | Color | Reset |
| --- | --- | --- |
| [`10`](https://control-codes.page/osc/foreground/index.html.md) | the default foreground, used by text with no SGR color | [`110`](https://control-codes.page/osc/reset-foreground/index.html.md) |
| [`11`](https://control-codes.page/osc/background/index.html.md) | the default background, behind text with no SGR background color | [`111`](https://control-codes.page/osc/reset-background/index.html.md) |
| [`12`](https://control-codes.page/osc/cursor-color/index.html.md) | the text cursor | [`112`](https://control-codes.page/osc/reset-cursor-color/index.html.md) |
| [`13`](https://control-codes.page/osc/pointer-foreground/index.html.md) | the mouse pointer, while it is over the window | [`113`](https://control-codes.page/osc/reset-pointer-foreground/index.html.md) |
| [`14`](https://control-codes.page/osc/pointer-background/index.html.md) | the mouse pointer's outline, the part of an X cursor drawn in its second color | [`114`](https://control-codes.page/osc/reset-pointer-background/index.html.md) |
| [`15`](https://control-codes.page/osc/tek-foreground/index.html.md) | what is drawn in xterm's Tektronix 4014 window | [`115`](https://control-codes.page/osc/reset-tek-foreground/index.html.md) |
| [`16`](https://control-codes.page/osc/tek-background/index.html.md) | the background of xterm's Tektronix 4014 window | [`116`](https://control-codes.page/osc/reset-tek-background/index.html.md) |
| [`17`](https://control-codes.page/osc/highlight-background/index.html.md) | the background of selected text | [`117`](https://control-codes.page/osc/reset-highlight-background/index.html.md) |
| [`18`](https://control-codes.page/osc/tek-cursor/index.html.md) | the cursor in xterm's Tektronix 4014 window | [`118`](https://control-codes.page/osc/reset-tek-cursor/index.html.md) |
| [`19`](https://control-codes.page/osc/highlight-foreground/index.html.md) | selected text | [`119`](https://control-codes.page/osc/reset-highlight-foreground/index.html.md) |

They all work alike:

- `OSC Ps ; Pt ST` sets color `Ps` to `Pt`, in any form X11's `XParseColor`
  accepts: a name such as `red`, `#rrggbb`, or `rgb:rr/gg/bb`.
- `Pt` of `?` asks for it. The answer is `OSC Ps ; rgb:rrrr/gggg/bbbb`,
  sixteen bits a part, ended with whichever of ST or BEL ended the question.
- A sequence can carry more than one color. Each further `;` moves on to the
  next number, so `OSC 10 ; red ; blue ST` sets the foreground and the
  background, and `OSC 10 ; ? ; ? ST` asks for both. An empty one is skipped,
  so `OSC 10 ; ; blue ST` sets only the background ([`ChangeColorsRequest`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/misc.c#L3662-L3715), [`ReportColorRequest`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/misc.c#L3568-L3598)).
- `OSC 1Ps ST`, that is `OSC 110 ST` to `OSC 119 ST`, puts color `Ps` back as
  it started ([`ResetColorsRequest`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/misc.c#L3718-L3753)).
- Neither [DECSTR](https://control-codes.page/csi/decstr/index.html.md) nor [RIS](https://control-codes.page/esc/ris/index.html.md) resets them, unlike the palette.

A program asks for the background, `OSC 11 ; ? ST`, to find out whether it is
running on a light or a dark terminal and choose its own colors to suit.

Where these colors start is the host's choice. The cases are run in a
terminal given a default xterm's: black text on white, with the cursor and
the mouse pointer in the foreground color
([`charproc.c`](https://github.com/ThomasDickey/xterm-snapshots/blob/xterm-411a/charproc.c#L540-L544)). That is what the answers below
report; it is not how this site draws the screens.

libghostty-vt has `10`, `11` and `12`, and `110` to `112`. It ignores the
rest, so a chain of questions that runs past `12` stops there. It also passes
over an empty color without moving on to the next number, so
`OSC 10 ; ; blue ST` sets its foreground. That case is a known difference.

## Support

| Terminal | Version | Support | Notes |
| --- | --- | --- | --- |
| VT220 | [manual](https://vt100.net/docs/vt220-rm/), 2nd ed., 1984 | No | OSC is not among the controls it recognizes ([§4.2](https://vt100.net/docs/vt220-rm/chapter4.html#S4.2)) |
| VT510 | [manual](https://vt100.net/docs/vt510-rm/), 1st ed., 1993 | No | ignores an OSC string ([chapter 4](https://vt100.net/docs/vt510-rm/chapter4.html)) |
| xterm | patch 412, [xterm-411a](https://github.com/ThomasDickey/xterm-snapshots/tree/xterm-411a) | Yes |  |
| libghostty-vt | [0f171f6](https://github.com/ghostty-org/ghostty/tree/0f171f650a1cbbd6df4a2573b6b0c7de57cc6d90) | Yes | passes over an empty entry (OSC10-4) |
| Konsole | 26.11.70, [a24c3d71](https://invent.kde.org/utilities/konsole/-/tree/a24c3d71be3684f24d030aa2dbe9bd723d985233) | Yes | sets and answers one color; no chain |
| kitty | 0.49.1, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/kitty.json) | Yes | passes the 2 cases that show it working; ends its replies with ST where xterm uses BEL |
| foot | 1.28.0, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/foot.json) | Partly | fails OSC10-3 of the 2 cases that show it working |
| pyte | 0.8.2, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/pyte.json) | No | fails the 2 cases that show it working |
| xterm.js headless | 6.0.0, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/xtermjs.json) | No | fails the 2 cases that show it working |
| alacritty_terminal | 0.26.0, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/alacritty.json) | Partly | fails OSC10-3 of the 2 cases that show it working |
| ConEmu | build 230724, its [documentation](https://conemu.github.io/en/AnsiEscapeCodes.html) | No | not in its [ANSI escape codes](https://conemu.github.io/en/AnsiEscapeCodes.html) |
| rxvt-unicode | 9.31, [run in a VM](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/urxvt.json) | Partly | fails OSC10-3 of the 2 cases that show it working; writes colors as `ff00` where xterm writes `ffff` |
| VTE | 0.84.1, [run as a library](https://git.jcollie.dev/jeff/control-codes/src/branch/main/emulators/results/vte.json) | Partly | fails OSC10-3 of the 2 cases that show it working |

## Validation

### OSC10-1: Ask for the foreground

Input, one step per line:

```text
\e]10;?\a
```

Expected screen:

```text
|____|
reply \e]10;rgb:0000/0000/0000\a
```

### OSC10-2: Change it

Input, one step per line:

```text
\e]10;#ff8000\a
\e]10;?\a
```

Expected screen:

```text
|____|
reply \e]10;rgb:ffff/8080/0000\a
```

### OSC10-3: Each ; moves to the next color

Input, one step per line:

```text
\e]10;red;blue\a
\e]10;?;?\a
```

Expected screen:

```text
|____|
reply \e]10;rgb:ffff/0000/0000\a\e]11;rgb:0000/0000/ffff\a
```

### OSC10-4: An empty one is skipped

*A known difference: libghostty-vt does not pass this case.*

Input, one step per line:

```text
\e]10;;blue\a
\e]10;?;?\a
```

Expected screen:

```text
|____|
reply \e]10;rgb:0000/0000/0000\a\e]11;rgb:0000/0000/ffff\a
```

### OSC10-5: Questions and changes together

Input, one step per line:

```text
\e]10;?;red\a  # ask for 10, set 11
\e]11;?\a
```

Expected screen:

```text
|____|
reply \e]10;rgb:0000/0000/0000\a\e]11;rgb:ffff/0000/0000\a
```

---

This is the Markdown version of <https://control-codes.page/osc/foreground/>. On that page every validation case runs live in libghostty-vt, the terminal emulation core of Ghostty, compiled to WebAssembly.

The validation cases are written in the notation described in <https://control-codes.page/notation/index.html.md>.
