Don't duplicate logs when running headless

BepInEx/Bootstrap/Chainloader.cs

@@ -10,6 +10,7 @@ using System.Text.RegularExpressions;
 using Mono.Cecil;
 using MonoMod.Utils;
 using UnityEngine;
+using UnityEngine.Rendering;
 using Logger = BepInEx.Logging.Logger;
 
 namespace BepInEx.Bootstrap
@@ -37,6 +38,13 @@ namespace BepInEx.Bootstrap
 			[MethodImpl(MethodImplOptions.NoInlining)]
 			get => Application.unityVersion;
 		}
+
+		// Check above for NoInlining reasoning
+		private static bool IsHeadless
+		{
+			[MethodImpl(MethodImplOptions.NoInlining)]
+			get => SystemInfo.graphicsDeviceType == GraphicsDeviceType.Null;
+		}
 		
 		/// <summary>
 		/// List of all <see cref="BepInPlugin"/> loaded via the chainloader.
@@ -88,7 +96,7 @@ namespace BepInEx.Bootstrap
 			}
 
 			// Start logging
-			if (ConsoleManager.ConsoleEnabled  && startConsole)
+			if (ConsoleManager.ConsoleEnabled && startConsole)
 			{
 				ConsoleManager.CreateConsole();
 				Logger.Listeners.Add(new ConsoleLogListener());
@@ -101,13 +109,21 @@ namespace BepInEx.Bootstrap
 
 			if (!TraceLogSource.IsListening)
 				Logger.Sources.Add(TraceLogSource.CreateSource());
-			
+
 			ReplayPreloaderLogs(preloaderLogEvents);
-			
+
 			// Add Unity log source only after replaying to prevent duplication in console
 			if (ConfigUnityLogging.Value)
 				Logger.Sources.Add(new UnityLogSource());
-			Logger.Listeners.Add(new UnityLogListener());
+
+			// Don't write to Unity logs in headless mode since Unity logs are already shown in console
+			if (!IsHeadless)
+				Logger.Listeners.Add(new UnityLogListener());
+			else
+			{
+				if (Logger.Listeners.FirstOrDefault(l => l is ConsoleLogListener) is ConsoleLogListener consoleLogListener)
+					consoleLogListener.WriteUnityLogs = false;
+			}
 
 			if (PlatformHelper.Is(Platform.Unix))
 			{

BepInEx/Logging/ConsoleLogListener.cs

@@ -8,9 +8,13 @@ namespace BepInEx.Logging
 	/// </summary>
 	public class ConsoleLogListener : ILogListener
 	{
+		public bool WriteUnityLogs { get; set; } = true;
+		
 		/// <inheritdoc />
 		public void LogEvent(object sender, LogEventArgs eventArgs)
 		{
+			if (!WriteUnityLogs && sender is UnityLogSource)
+				return;
 			if ((eventArgs.Level & ConfigConsoleDisplayedLevel.Value) == 0)
 				return;