Support IShellLaunchConfig.initialText

Fixes #22377

src/vs/workbench/parts/terminal/common/terminal.ts

@@ -102,6 +102,13 @@ export interface IShellLaunchConfig {
 	ignoreConfigurationCwd?: boolean;
 	/** Whether to wait for a key press before closing the terminal. */
 	waitOnExit?: boolean;
+	/**
+	 * A string including ANSI escape sequences that will be written to the terminal emulator
+	 * _before_ the terminal process has launched, a trailing \n is added at the end of the string.
+	 * This allows for example the terminal instance to display a styled message as the first line
+	 * of the terminal. Use \x1b over \033 or \e for the escape control character.
+	 */
+	initialText?: string;
 }
 
 export interface ITerminalService {

src/vs/workbench/parts/terminal/electron-browser/terminalInstance.ts

@@ -192,6 +192,9 @@ export class TerminalInstance implements ITerminalInstance {
 		this._xterm = xterm({
 			scrollback: this._configHelper.config.scrollback
 		});
+		if (this._shellLaunchConfig.initialText) {
+			this._xterm.writeln(this._shellLaunchConfig.initialText);
+		}
 		this._process.on('message', (message) => this._sendPtyDataToXterm(message));
 		this._xterm.on('data', (data) => {
 			if (this._process) {