OSC 12 Text Cursor Color
Set and query the color of the text cursor.
OSC 12 ; Pt ST
OSC 12 ; Pt ST sets the color of the text cursor, and OSC 12 ; ? ST asks what it is. OSC 112 puts it back as it started. It is one of xterm’s dynamic colors, and works as OSC 10 explains: Pt is any color X11 can parse, and a further ; in the same sequence moves on to color 13.
A default xterm starts it as the cursorColor resource, which is the foreground (charproc.c), so in the terminal the cases run in, set up as a default xterm, it is reported as rgb:0000/0000/0000.
libghostty-vt has it, and agrees with xterm.
Support
| Terminal | Version | Support | Notes |
|---|---|---|---|
| VT220 | manual, 2nd ed., 1984 | No | OSC is not among the controls it recognizes (§4.2) |
| VT510 | manual, 1st ed., 1993 | No | ignores an OSC string (chapter 4) |
| xterm | patch 412, xterm-411a | Yes | |
| libghostty-vt | 0f171f6 | Yes | a chain stops after 12 (OSC12-3) |
| Konsole | 26.11.70, a24c3d71 | Partly | sets it, but does not answer ? |
| kitty | 0.49.1, run in a VM | Yes | passes the case that shows it working; ends its replies with ST where xterm uses BEL |
| foot | 1.28.0, run in a VM | Yes | passes the case that shows it working |
| pyte | 0.8.2, run as a library | No | fails the case that shows it working |
| xterm.js headless | 6.0.0, run as a library | No | fails the case that shows it working |
| alacritty_terminal | 0.26.0, run as a library | Yes | passes the case that shows it working |
| ConEmu | build 230724, its documentation | No | not in its ANSI escape codes |
| rxvt-unicode | 9.31, run in a VM | Yes | passes the case that shows it working; writes colors as ff00 where xterm writes ffff |
| VTE | 0.84.1, run as a library | Yes | passes the case that shows it working |
Validation
OSC12-1: Ask for it
\e]12;?\a
|____|
reply \e]12;rgb:0000/0000/0000\a
OSC12-2: Change it
\e]12;#0080ff\a
\e]12;?\a
|____|
reply \e]12;rgb:0000/8080/ffff\a
OSC12-3: A chain past the cursor
\e]12;?;?\a # the cursor, then the pointer
|____|
reply \e]12;rgb:0000/0000/0000\a\e]13;rgb:0000/0000/0000\a