diff --git a/src/docfx/Models/BuildCommand.cs b/src/docfx/Models/BuildCommand.cs
index b3792858941..dce4fa8d58a 100644
--- a/src/docfx/Models/BuildCommand.cs
+++ b/src/docfx/Models/BuildCommand.cs
@@ -13,22 +13,15 @@ public override int Execute(CommandContext context, BuildCommandOptions settings
     {
         return CommandHelper.Run(settings, () =>
         {
-            var config = ParseOptions(settings, out var baseDirectory, out var outputFolder);
-            var serveDirectory = RunBuild.Exec(config, new(), baseDirectory, outputFolder);
+            var (config, baseDirectory) = CommandHelper.GetConfig<BuildConfig>(settings.ConfigFile);
+            MergeOptionsToConfig(settings, config.Item, baseDirectory);
+            var serveDirectory = RunBuild.Exec(config.Item, new(), baseDirectory, settings.OutputFolder);
 
             if (settings.Serve)
                 RunServe.Exec(serveDirectory, settings.Host, settings.Port);
         });
     }
 
-    private static BuildJsonConfig ParseOptions(BuildCommandOptions options, out string baseDirectory, out string outputFolder)
-    {
-        (var config, baseDirectory) = CommandHelper.GetConfig<BuildConfig>(options.ConfigFile);
-        outputFolder = options.OutputFolder;
-        MergeOptionsToConfig(options, config.Item, baseDirectory);
-        return config.Item;
-    }
-
     internal static void MergeOptionsToConfig(BuildCommandOptions options, BuildJsonConfig config, string configDirectory)
     {
         // base directory for content from command line is current directory
diff --git a/src/docfx/Models/DefaultCommand.cs b/src/docfx/Models/DefaultCommand.cs
index e8fcb703a94..4e4609785a9 100644
--- a/src/docfx/Models/DefaultCommand.cs
+++ b/src/docfx/Models/DefaultCommand.cs
@@ -12,31 +12,11 @@ namespace Microsoft.DocAsCode;
 class DefaultCommand : Command<DefaultCommand.Options>
 {
     [Description("Runs metadata, build and pdf commands")]
-    internal class Options : LogOptions
+    internal class Options : BuildCommandOptions
     {
         [Description("Prints version information")]
         [CommandOption("-v|--version")]
         public bool Version { get;set; }
-
-        [Description("Specify the output base directory")]
-        [CommandOption("-o|--output")]
-        public string OutputFolder { get; set; }
-
-        [Description("Host the generated documentation to a website")]
-        [CommandOption("-s|--serve")]
-        public bool Serve { get; set; }
-
-        [Description("Specify the hostname of the hosted website [localhost]")]
-        [CommandOption("-n|--hostname")]
-        public string Host { get; set; }
-
-        [Description("Specify the port of the hosted website [8080]")]
-        [CommandOption("-p|--port")]
-        public int? Port { get; set; }
-
-        [Description("Path to docfx.json")]
-        [CommandArgument(0, "[config]")]
-        public string Config { get; set; }
     }
 
     public override int Execute(CommandContext context, Options options)
@@ -49,18 +29,29 @@ public override int Execute(CommandContext context, Options options)
 
         return CommandHelper.Run(options, () =>
         {
-            var (config, baseDirectory) = CommandHelper.GetConfig<Config>(options.Config);
+            var (config, baseDirectory) = CommandHelper.GetConfig<Config>(options.ConfigFile);
             var outputFolder = options.OutputFolder;
             string serveDirectory = null;
 
             if (config.Metadata is not null)
                 DotnetApiCatalog.Exec(config.Metadata, new(), baseDirectory, outputFolder).GetAwaiter().GetResult();
+
             if (config.Build is not null)
+            {
+                BuildCommand.MergeOptionsToConfig(options, config.Build, baseDirectory);
                 serveDirectory = RunBuild.Exec(config.Build, new(), baseDirectory, outputFolder);
+            }
+
             if (config.Pdf is not null)
+            {
+                BuildCommand.MergeOptionsToConfig(options, config.Pdf, baseDirectory);
                 RunPdf.Exec(config.Pdf, new(), baseDirectory, outputFolder);
+            }
+
             if (options.Serve && serveDirectory is not null)
+            {
                 RunServe.Exec(serveDirectory, options.Host, options.Port);
+            }
         });
     }
 
diff --git a/src/docfx/Models/PdfCommand.cs b/src/docfx/Models/PdfCommand.cs
index a3d10aeb9e8..37af32e829e 100644
--- a/src/docfx/Models/PdfCommand.cs
+++ b/src/docfx/Models/PdfCommand.cs
@@ -13,19 +13,12 @@ public override int Execute([NotNull] CommandContext context, [NotNull] PdfComma
     {
         return CommandHelper.Run(options, () =>
         {
-            var Config = ParseOptions(options, out var BaseDirectory, out var OutputFolder);
-            RunPdf.Exec(Config, new(), BaseDirectory, OutputFolder);
+            var (config, baseDirectory) = CommandHelper.GetConfig<PdfConfig>(options.ConfigFile);
+            MergeOptionsToConfig(options, config.Item, baseDirectory);
+            RunPdf.Exec(config.Item, new(), baseDirectory, options.OutputFolder);
         });
     }
 
-    private static PdfJsonConfig ParseOptions(PdfCommandOptions options, out string baseDirectory, out string outputFolder)
-    {
-        (var config, baseDirectory) = CommandHelper.GetConfig<PdfConfig>(options.ConfigFile);
-        outputFolder = options.OutputFolder;
-        MergeOptionsToConfig(options, config.Item, baseDirectory);
-        return config.Item;
-    }
-
     private static void MergeOptionsToConfig(PdfCommandOptions options, PdfJsonConfig config, string configDirectory)
     {
         BuildCommand.MergeOptionsToConfig(options, config, configDirectory);
diff --git a/src/docfx/Models/ServeCommand.cs b/src/docfx/Models/ServeCommand.cs
index dda2c14a7d3..0031763d57a 100644
--- a/src/docfx/Models/ServeCommand.cs
+++ b/src/docfx/Models/ServeCommand.cs
@@ -16,11 +16,11 @@ internal class Settings : CommandSettings
         [CommandArgument(0, "[directory]")]
         public string Folder { get; set; }
 
-        [Description("Specify the hostname of the hosted website [localhost]")]
+        [Description("Specify the hostname of the hosted website")]
         [CommandOption("-n|--hostname")]
         public string Host { get; set; }
 
-        [Description("Specify the port of the hosted website [8080]")]
+        [Description("Specify the port of the hosted website")]
         [CommandOption("-p|--port")]
         public int? Port { get; set; }
     }
diff --git a/test/docfx.Tests/CommandLineTest.cs b/test/docfx.Tests/CommandLineTest.cs
new file mode 100644
index 00000000000..9ba74f0f3e8
--- /dev/null
+++ b/test/docfx.Tests/CommandLineTest.cs
@@ -0,0 +1,37 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Xunit;
+
+namespace Microsoft.DocAsCode.Tests;
+
+public static class CommandLineTest
+{
+    [Fact]
+    public static void PrintsVersion()
+    {
+        Assert.Equal(0, Program.Main(new[] { "-v" }));
+        Assert.Equal(0, Program.Main(new[] { "--version" }));
+    }
+
+    [Fact]
+    public static void PrintsHelp()
+    {
+        Assert.Equal(0, Program.Main(new[] { "-h" }));
+        Assert.Equal(0, Program.Main(new[] { "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "build", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "serve", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "metadata", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "pdf", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "init", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "download", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "merge", "--help" }));
+        Assert.Equal(0, Program.Main(new[] { "template", "--help" }));
+    }
+
+    [Fact]
+    public static void FailForUnknownArgs()
+    {
+        Assert.Equal(-1, Program.Main(new[] { "--unknown" }));
+    }
+}