diff --git a/sample/SkyApm.Sample.GeneralHost/Program.cs b/sample/SkyApm.Sample.GeneralHost/Program.cs
new file mode 100644
index 0000000000000000000000000000000000000000..51844b9276265ce1d6fdf7c0c7fe88a3ac1775a0
--- /dev/null
+++ b/sample/SkyApm.Sample.GeneralHost/Program.cs
@@ -0,0 +1,19 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using SkyApm.Agent.GeneralHost;
+
+namespace SkyApm.Sample.GeneralHost
+{
+    public class Program
+    {
+        public static void Main(string[] args)
+        {
+            CreateHostBuilder(args).Build().Run();
+        }
+
+        public static IHostBuilder CreateHostBuilder(string[] args) =>
+            new HostBuilder()
+                .ConfigureServices(services => services.AddHostedService<Worker>())
+                .AddSkyAPM();
+    }
+}
diff --git a/sample/SkyApm.Sample.GeneralHost/SkyApm.Sample.GeneralHost.csproj b/sample/SkyApm.Sample.GeneralHost/SkyApm.Sample.GeneralHost.csproj
new file mode 100644
index 0000000000000000000000000000000000000000..fd74aef77f396374f77e426984c8ad575ad32acc
--- /dev/null
+++ b/sample/SkyApm.Sample.GeneralHost/SkyApm.Sample.GeneralHost.csproj
@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <OutputType>Exe</OutputType>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Content Include="skyapm.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+    </Content>
+
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="2.1.1" />
+    <ProjectReference Include="..\..\src\SkyApm.Agent.GeneralHost\SkyApm.Agent.GeneralHost.csproj" />
+  </ItemGroup>
+
+</Project>
diff --git a/sample/SkyApm.Sample.GeneralHost/Worker.cs b/sample/SkyApm.Sample.GeneralHost/Worker.cs
new file mode 100644
index 0000000000000000000000000000000000000000..1296afe678aa0da057ea67aadcbdfaebfb0983ac
--- /dev/null
+++ b/sample/SkyApm.Sample.GeneralHost/Worker.cs
@@ -0,0 +1,34 @@
+using Microsoft.Extensions.Hosting;
+using SkyApm.Tracing;
+using SkyApm.Tracing.Segments;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace SkyApm.Sample.GeneralHost
+{
+    public class Worker : BackgroundService
+    {
+        private readonly ITracingContext _tracingContext;
+
+        public Worker(ITracingContext tracingContext)
+        {
+            _tracingContext = tracingContext;
+        }
+
+        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
+        {
+            while (!stoppingToken.IsCancellationRequested)
+            {
+                var context = _tracingContext.CreateEntrySegmentContext(nameof(ExecuteAsync), new TextCarrierHeaderCollection(new Dictionary<string, string>()));
+
+                await Task.Delay(1000, stoppingToken);
+
+                context.Span.AddLog(LogEvent.Message($"Worker running at: {DateTime.Now}"));
+
+                _tracingContext.Release(context);
+            }
+        }
+    }
+}
diff --git a/sample/SkyApm.Sample.GeneralHost/skyapm.json b/sample/SkyApm.Sample.GeneralHost/skyapm.json
new file mode 100644
index 0000000000000000000000000000000000000000..29a19b8dafba457d38a581d16bb5a9baad7e94e8
--- /dev/null
+++ b/sample/SkyApm.Sample.GeneralHost/skyapm.json
@@ -0,0 +1,29 @@
+{
+  "SkyWalking": {
+    "ServiceName": "general-host-sample",
+    "Namespace": "",
+    "HeaderVersions": [
+      "sw6"
+    ],
+    "Sampling": {
+      "SamplePer3Secs": -1,
+      "Percentage": -1.0
+    },
+    "Logging": {
+      "Level": "Information",
+      "FilePath": "logs/skyapm-{Date}.log"
+    },
+    "Transport": {
+      "Interval": 3000,
+      "ProtocolVersion": "v6",
+      "QueueSize": 30000,
+      "BatchSize": 3000,
+      "gRPC": {
+        "Servers": "localhost:11800",
+        "Timeout": 100000,
+        "ConnectTimeout": 100000,
+        "ReportTimeout": 600000
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/skyapm-dotnet.sln b/skyapm-dotnet.sln
index a0ed237635ee4d4a73fe4d60d5be044a1ec812c0..7d2cb5ab6c0f0fec6fce78405a0bf58831b6c742 100644
--- a/skyapm-dotnet.sln
+++ b/skyapm-dotnet.sln
@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 15
-VisualStudioVersion = 15.0.27130.2024
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.28729.10
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{05BF0D4E-C824-4EC8-8330-36C1FC49910E}"
 EndProject
@@ -82,7 +82,11 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkyApm.DotNet.CLI", "src\Sk
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkyApm.Diagnostics.SmartSql", "src\SkyApm.Diagnostics.SmartSql\SkyApm.Diagnostics.SmartSql.csproj", "{B43160C8-C9E3-43F6-83E9-A9A45B32F022}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "SkyApm.Sample.SmartSql", "sample\SkyApm.Sample.SmartSql\SkyApm.Sample.SmartSql.csproj", "{8E2B336B-8138-4179-A754-A1D0C0471654}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkyApm.Sample.SmartSql", "sample\SkyApm.Sample.SmartSql\SkyApm.Sample.SmartSql.csproj", "{8E2B336B-8138-4179-A754-A1D0C0471654}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkyApm.Agent.GeneralHost", "src\SkyApm.Agent.GeneralHost\SkyApm.Agent.GeneralHost.csproj", "{4C1CF0E7-4CD3-4731-9A56-E033D5216D58}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SkyApm.Sample.GeneralHost", "sample\SkyApm.Sample.GeneralHost\SkyApm.Sample.GeneralHost.csproj", "{477D705E-576B-46C8-8F1E-9A86EDAE9D86}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -182,6 +186,14 @@ Global
 		{8E2B336B-8138-4179-A754-A1D0C0471654}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{8E2B336B-8138-4179-A754-A1D0C0471654}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{8E2B336B-8138-4179-A754-A1D0C0471654}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4C1CF0E7-4CD3-4731-9A56-E033D5216D58}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4C1CF0E7-4CD3-4731-9A56-E033D5216D58}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4C1CF0E7-4CD3-4731-9A56-E033D5216D58}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4C1CF0E7-4CD3-4731-9A56-E033D5216D58}.Release|Any CPU.Build.0 = Release|Any CPU
+		{477D705E-576B-46C8-8F1E-9A86EDAE9D86}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{477D705E-576B-46C8-8F1E-9A86EDAE9D86}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{477D705E-576B-46C8-8F1E-9A86EDAE9D86}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{477D705E-576B-46C8-8F1E-9A86EDAE9D86}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -218,6 +230,8 @@ Global
 		{E909EEF5-5EBF-43F3-AB4A-6B2FB56EF89B} = {1B0865AF-369E-493C-AA6F-C56D3E520A22}
 		{B43160C8-C9E3-43F6-83E9-A9A45B32F022} = {B5E677CF-2920-4B0A-A056-E73F6B2CF2BC}
 		{8E2B336B-8138-4179-A754-A1D0C0471654} = {844CEACD-4C85-4B15-9E2B-892B01FDA4BB}
+		{4C1CF0E7-4CD3-4731-9A56-E033D5216D58} = {EF6194B2-9ACB-49B9-8049-DD6AFAEB0399}
+		{477D705E-576B-46C8-8F1E-9A86EDAE9D86} = {844CEACD-4C85-4B15-9E2B-892B01FDA4BB}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {94C0DA2C-CCCB-4314-93A2-9809B5DD0583}
diff --git a/src/SkyApm.Agent.GeneralHost/Extensions/HostBuilderExtensions.cs b/src/SkyApm.Agent.GeneralHost/Extensions/HostBuilderExtensions.cs
new file mode 100644
index 0000000000000000000000000000000000000000..b3ec44de7c721718c6e9956020dcde86d43e147b
--- /dev/null
+++ b/src/SkyApm.Agent.GeneralHost/Extensions/HostBuilderExtensions.cs
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the SkyAPM under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The SkyAPM licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+using Microsoft.Extensions.Hosting;
+
+namespace SkyApm.Agent.GeneralHost
+{
+    public static class HostBuilderExtensions
+    {
+        public static IHostBuilder AddSkyAPM(this IHostBuilder builder) =>
+            builder.ConfigureServices((context, services) => services.AddSkyAPMCore());
+    }
+}
\ No newline at end of file
diff --git a/src/SkyApm.Agent.GeneralHost/Extensions/ServiceCollectionExtensions.cs b/src/SkyApm.Agent.GeneralHost/Extensions/ServiceCollectionExtensions.cs
new file mode 100644
index 0000000000000000000000000000000000000000..1f52b4d2ae262df81657d7f3d21fe156801e7e80
--- /dev/null
+++ b/src/SkyApm.Agent.GeneralHost/Extensions/ServiceCollectionExtensions.cs
@@ -0,0 +1,112 @@
+/*
+ * Licensed to the SkyAPM under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The SkyAPM licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using SkyApm.Config;
+using SkyApm.Diagnostics;
+using SkyApm.Diagnostics.EntityFrameworkCore;
+using SkyApm.Diagnostics.HttpClient;
+using SkyApm.Diagnostics.SqlClient;
+using SkyApm.Logging;
+using SkyApm.Sampling;
+using SkyApm.Service;
+using SkyApm.Tracing;
+using SkyApm.Transport;
+using SkyApm.Transport.Grpc;
+using SkyApm.Transport.Grpc.V5;
+using SkyApm.Transport.Grpc.V6;
+using SkyApm.Utilities.Configuration;
+using SkyApm.Utilities.DependencyInjection;
+using SkyApm.Utilities.Logging;
+using System;
+
+namespace SkyApm.Agent.GeneralHost
+{
+    internal static class ServiceCollectionExtensions
+    {
+        internal static IServiceCollection AddSkyAPMCore(this IServiceCollection services)
+        {
+            if (services == null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+
+            services.AddSingleton<ISegmentDispatcher, AsyncQueueSegmentDispatcher>();
+            services.AddSingleton<IExecutionService, RegisterService>();
+            services.AddSingleton<IExecutionService, PingService>();
+            services.AddSingleton<IExecutionService, ServiceDiscoveryV5Service>();
+            services.AddSingleton<IExecutionService, SegmentReportService>();
+            services.AddSingleton<IInstrumentStartup, InstrumentStartup>();
+            services.AddSingleton<IRuntimeEnvironment>(RuntimeEnvironment.Instance);
+            services.AddSingleton<TracingDiagnosticProcessorObserver>();
+            services.AddSingleton<IConfigAccessor, ConfigAccessor>();
+            services.AddSingleton<IConfigurationFactory, ConfigurationFactory>();
+            services.AddSingleton<IHostedService, InstrumentationHostedService>();
+            services.AddSingleton<IEnvironmentProvider, HostingEnvironmentProvider>();
+            services.AddTracing().AddSampling().AddGrpcTransport().AddLogging();
+            services.AddSkyApmExtensions().AddHttpClient().AddSqlClient()
+                .AddEntityFrameworkCore(c => c.AddPomeloMysql().AddNpgsql().AddSqlite());
+            return services;
+        }
+
+        private static IServiceCollection AddTracing(this IServiceCollection services)
+        {
+            services.AddSingleton<ITracingContext, Tracing.TracingContext>();
+            services.AddSingleton<ICarrierPropagator, CarrierPropagator>();
+            services.AddSingleton<ICarrierFormatter, Sw3CarrierFormatter>();
+            services.AddSingleton<ICarrierFormatter, Sw6CarrierFormatter>();
+            services.AddSingleton<ISegmentContextFactory, SegmentContextFactory>();
+            services.AddSingleton<IEntrySegmentContextAccessor, EntrySegmentContextAccessor>();
+            services.AddSingleton<ILocalSegmentContextAccessor, LocalSegmentContextAccessor>();
+            services.AddSingleton<IExitSegmentContextAccessor, ExitSegmentContextAccessor>();
+            services.AddSingleton<ISamplerChainBuilder, SamplerChainBuilder>();
+            services.AddSingleton<IUniqueIdGenerator, UniqueIdGenerator>();
+            services.AddSingleton<IUniqueIdParser, UniqueIdParser>();
+            services.AddSingleton<ISegmentContextMapper, SegmentContextMapper>();
+            services.AddSingleton<IBase64Formatter, Base64Formatter>();
+            return services;
+        }
+
+        private static IServiceCollection AddSampling(this IServiceCollection services)
+        {
+            services.AddSingleton<SimpleCountSamplingInterceptor>();
+            services.AddSingleton<ISamplingInterceptor>(p => p.GetService<SimpleCountSamplingInterceptor>());
+            services.AddSingleton<IExecutionService>(p => p.GetService<SimpleCountSamplingInterceptor>());
+            services.AddSingleton<ISamplingInterceptor, RandomSamplingInterceptor>();
+            return services;
+        }
+
+        private static IServiceCollection AddGrpcTransport(this IServiceCollection services)
+        {
+            services.AddSingleton<ISkyApmClientV5, SkyApmClientV5>();
+            services.AddSingleton<ISegmentReporter, SegmentReporter>();
+            services.AddSingleton<ConnectionManager>();
+            services.AddSingleton<IPingCaller, PingCaller>();
+            services.AddSingleton<IServiceRegister, ServiceRegister>();
+            services.AddSingleton<IExecutionService, ConnectService>();
+            return services;
+        }
+
+        private static IServiceCollection AddLogging(this IServiceCollection services)
+        {
+            services.AddSingleton<ILoggerFactory, DefaultLoggerFactory>();
+            return services;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/SkyApm.Agent.GeneralHost/HostingEnvironmentProvider.cs b/src/SkyApm.Agent.GeneralHost/HostingEnvironmentProvider.cs
new file mode 100644
index 0000000000000000000000000000000000000000..379b659e152accc69b65df4a31603d39c809978f
--- /dev/null
+++ b/src/SkyApm.Agent.GeneralHost/HostingEnvironmentProvider.cs
@@ -0,0 +1,32 @@
+/*
+ * Licensed to the SkyAPM under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The SkyAPM licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+using Microsoft.Extensions.Hosting;
+
+namespace SkyApm.Agent.GeneralHost
+{
+    internal class HostingEnvironmentProvider : IEnvironmentProvider
+    {
+        public string EnvironmentName { get; }
+
+        public HostingEnvironmentProvider(IHostingEnvironment hostingEnvironment)
+        {
+            EnvironmentName = hostingEnvironment.EnvironmentName;
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/SkyApm.Agent.GeneralHost/InstrumentationHostedService.cs b/src/SkyApm.Agent.GeneralHost/InstrumentationHostedService.cs
new file mode 100644
index 0000000000000000000000000000000000000000..57f31f979282cafdd05b032af23a11a6d8e64f4c
--- /dev/null
+++ b/src/SkyApm.Agent.GeneralHost/InstrumentationHostedService.cs
@@ -0,0 +1,44 @@
+/*
+ * Licensed to the SkyAPM under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The SkyAPM licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Hosting;
+
+namespace SkyApm.Agent.GeneralHost
+{
+    internal class InstrumentationHostedService : IHostedService
+    {
+        private readonly IInstrumentStartup _startup;
+
+        public InstrumentationHostedService(IInstrumentStartup startup)
+        {
+            _startup = startup;
+        }
+
+        public Task StartAsync(CancellationToken cancellationToken)
+        {
+            return _startup.StartAsync(cancellationToken);
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            return _startup.StopAsync(cancellationToken);
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/SkyApm.Agent.GeneralHost/SkyApm.Agent.GeneralHost.csproj b/src/SkyApm.Agent.GeneralHost/SkyApm.Agent.GeneralHost.csproj
new file mode 100644
index 0000000000000000000000000000000000000000..935cc209c2cbd85bd9df998469de0a271cbceb75
--- /dev/null
+++ b/src/SkyApm.Agent.GeneralHost/SkyApm.Agent.GeneralHost.csproj
@@ -0,0 +1,31 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <Import Project="..\..\build\common.props" />
+    <PropertyGroup>
+        <Description>$(Product) ASP.NET Core Agent.</Description>
+        <AssemblyTitle>$(PackagePrefix).Agent.GeneralHost</AssemblyTitle>
+        <AssemblyName>$(PackagePrefix).Agent.GeneralHost</AssemblyName>
+        <PackageId>$(PackagePrefix).Agent.GeneralHost</PackageId>
+        <PackageTags>SkyWalking;APM</PackageTags>
+        <PackageReleaseNotes>
+        </PackageReleaseNotes>
+        <RootNamespace>SkyApm.Agent.GeneralHost</RootNamespace>
+        <TargetFramework>netstandard2.0</TargetFramework>
+    </PropertyGroup>
+    <ItemGroup>
+        <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="2.1.0" PrivateAssets="All" />
+    </ItemGroup>
+    <ItemGroup>
+        <ProjectReference Include="..\SkyApm.Abstractions\SkyApm.Abstractions.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.EntityFrameworkCore.Npgsql\SkyApm.Diagnostics.EntityFrameworkCore.Npgsql.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.EntityFrameworkCore.Pomelo.MySql\SkyApm.Diagnostics.EntityFrameworkCore.Pomelo.MySql.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.EntityFrameworkCore.Sqlite\SkyApm.Diagnostics.EntityFrameworkCore.Sqlite.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.EntityFrameworkCore\SkyApm.Diagnostics.EntityFrameworkCore.csproj" />
+        <ProjectReference Include="..\SkyApm.Core\SkyApm.Core.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.HttpClient\SkyApm.Diagnostics.HttpClient.csproj" />
+        <ProjectReference Include="..\SkyApm.Diagnostics.SqlClient\SkyApm.Diagnostics.SqlClient.csproj" />
+        <ProjectReference Include="..\SkyApm.Transport.Grpc\SkyApm.Transport.Grpc.csproj" />
+        <ProjectReference Include="..\SkyApm.Utilities.Configuration\SkyApm.Utilities.Configuration.csproj" />
+        <ProjectReference Include="..\SkyApm.Utilities.DependencyInjection\SkyApm.Utilities.DependencyInjection.csproj" />
+        <ProjectReference Include="..\SkyApm.Utilities.Logging\SkyApm.Utilities.Logging.csproj" />
+    </ItemGroup>
+</Project>
\ No newline at end of file