Add selfinstall --skip-env to avoid shell/profile mutation

src/dnvm/CommandLineArguments.cs

@@ -105,6 +105,9 @@ public sealed partial record SelfInstallArgs : DnvmSubCommand
 
         [CommandOption("--skip-tracking", Description = "Skip channel tracking and SDK installation during self-install.")]
         public bool? SkipTracking { get; init; } = null;
+
+        [CommandOption("--skip-env", Description = "Skip modifying shell profiles and user environment during self-install.")]
+        public bool? SkipEnv { get; init; } = null;
     }
 
     [Command("update", Summary = "Update the installed SDKs or dnvm itself.")]

src/dnvm/SelfInstallCommand.cs

@@ -40,6 +40,10 @@ public sealed record Options
         /// Skip channel tracking and SDK installation during self-install.
         /// </summary>
         public bool SkipTracking { get; init; } = false;
+        /// <summary>
+        /// Skip modifying shell profiles and the user environment during self-install.
+        /// </summary>
+        public bool SkipEnv { get; init; } = false;
     }
 
     private readonly DnvmEnv _env;
@@ -64,7 +68,8 @@ public static Task<Result> Run(DnvmEnv env, Logger logger, DnvmSubCommand.SelfIn
             Yes = args.Yes ?? false,
             Update = args.Update ?? false,
             DestPath = args.DestPath,
-            SkipTracking = args.SkipTracking ?? false
+            SkipTracking = args.SkipTracking ?? false,
+            SkipEnv = args.SkipEnv ?? false
         });
     }
 
@@ -150,7 +155,7 @@ public static async Task<Result> Run(DnvmEnv env, Logger logger, Options opt)
 
         var updateUserEnv = true;
         var sdkDirName = DnvmEnv.DefaultSdkDirName;
-        if (!opt.Yes && MissingFromEnv(env, sdkDirName))
+        if (!opt.SkipEnv && !opt.Yes && MissingFromEnv(env, sdkDirName))
         {
             console.WriteLine("One or more paths are missing from the user environment. Attempt to update the user environment?");
             console.Write("[Y/n]> ");
@@ -226,7 +231,7 @@ public async Task<Result> Run(string targetPath, Channel channel, SdkDirName new
         SelectCommand.SelectDir(_logger, _env, oldDirName, newDirName);
 
         // Set up path
-        if (updateUserEnv)
+        if (updateUserEnv && !_opts.SkipEnv)
         {
             await UpdateEnv(_logger, _env, newDirName);
         }

test/IntegrationTests/SelfInstallTests.cs

@@ -79,6 +79,30 @@ public Task SelfInstallSkipTracking() => RunWithServer(async (mockServer, env) =
         }
     });
 
+    [ConditionalFact(typeof(UnixOnly))]
+    public Task SelfInstallSkipEnv() => RunWithServer(async (mockServer, env) =>
+    {
+        var zshrcPath = Path.Combine(env.UserHome, ".zshrc");
+        const string initialZshrcContent = "# Existing zsh config";
+        await File.WriteAllTextAsync(zshrcPath, initialZshrcContent);
+
+        var procResult = await DnvmRunner.RunAndRestoreEnv(
+            env,
+            DnvmExe,
+            $"selfinstall --feed-url {mockServer.PrefixString} -y -v --skip-env"
+        );
+
+        _testOutput.WriteLine(procResult.Out);
+        _testOutput.WriteLine(procResult.Error);
+        Assert.Equal(0, procResult.ExitCode);
+
+        var dnvmPath = env.DnvmHomeFs.ConvertPathToInternal(DnvmEnv.DnvmExePath);
+        Assert.True(File.Exists(dnvmPath));
+        Assert.False(env.DnvmHomeFs.FileExists(DnvmEnv.EnvPath));
+        Assert.Equal(initialZshrcContent, await File.ReadAllTextAsync(zshrcPath));
+        Assert.DoesNotContain("Scanning for shell files", procResult.Out);
+    });
+
     [ConditionalFact(typeof(UnixOnly))]
     public async Task SelfInstallDialog() => await RunWithServer(async (mockServer, env) =>
     {

test/UnitTests/CommandLineTests.cs

@@ -322,7 +322,8 @@ public void SelfInstallHelp(string param)
             [ "selfinstall", param ]));
         Assert.Equal("""
 usage: dnvm selfinstall [-v | --verbose] [-f | --force] [--feed-url <feedUrl>]
-[-y] [--update] [--dest-path <destPath>] [--skip-tracking] [-h | --help]
+[-y] [--update] [--dest-path <destPath>] [--skip-tracking] [--skip-env] [-h |
+--help]
 
 Install dnvm to the local machine.
 
@@ -335,6 +336,8 @@ Install dnvm to the local machine.
 be called from dnvm.
     --dest-path  <destPath>  Set the destination path for the dnvm executable.
     --skip-tracking  Skip channel tracking and SDK installation during
+self-install.
+    --skip-env  Skip modifying shell profiles and user environment during
 self-install.
     -h, --help  Show help information.