OSC 6 Enable Special Color
Turn on or off xterm's use of a special color for bold, underlined, blinking, reversed or italic text.
OSC 6 ; Pc ; Pf ST
OSC 6 ; Pc ; Pf ST turns on, when Pf is not zero, or off, when it is, xterm’s use of special color Pc: 0 for bold, 1 underline, 2 blink, 3 reverse, 4 italic. While a mode is on, text with that attribute is drawn in its special color. OSC 106 is the same as OSC 6, and a pair can be repeated, OSC 6 ; 0 ; 1 ; 1 ; 1 ST turning on bold and underline (do_osc). The modes start as the colorBDMode, colorULMode and similar resources say, all off by default, and nothing is answered.
The number means something else to iTerm2, which uses OSC 6 ; 1 ; bg ; red ; brightness ; N ST to color its tab (see the iTerm2 page). xterm reads the 1 and then stops at bg, which is not a number, so iTerm2’s sequence changes nothing there.
A case cannot see a special color mode, which changes only how text is drawn. libghostty-vt has neither special colors nor these modes, and ignores OSC 6; what a case can see, that nothing is printed or answered, is the same as in 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 | modes start off, per colorBDMode and similar resources |
| libghostty-vt | 0f171f6 | No | ignored |
| Konsole | 26.11.70, a24c3d71 | No | |
| iTerm2 | 3.7.3, its documentation | No | uses OSC 6 to color its tab instead (iTerm2) |
| ConEmu | build 230724, its documentation | No | not in ConEmu’s list, ANSI escape codes |
Validation
OSC6-1: Nothing on screen, nothing answered
A
\e]6;0;1\a # bold in its special color
\e]6;0;0;1;1\a # bold off, underline on
\e]6;1;bg;red;brightness;255\a # iTerm2's tab color
B
|AB____|
cursor 1,3
reply none