ktsu.SingleAppInstance 1.2.5

Prefix Reserved
.NET 8.0 This package targets .NET 8.0. The package is compatible with this framework or higher.
There is a newer prerelease version of this package available.
See the version list below for details. 
dotnet add package ktsu.SingleAppInstance --version 1.2.5
                    


                    

                
NuGet\Install-Package ktsu.SingleAppInstance -Version 1.2.5
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="ktsu.SingleAppInstance" Version="1.2.5" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="ktsu.SingleAppInstance" Version="1.2.5" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="ktsu.SingleAppInstance" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add ktsu.SingleAppInstance --version 1.2.5
                    


                    

                
#r "nuget: ktsu.SingleAppInstance, 1.2.5"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#addin nuget:?package=ktsu.SingleAppInstance&version=1.2.5
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=ktsu.SingleAppInstance&version=1.2.5
                    


                            Install as a Cake Tool

ktsu.SingleAppInstance

A .NET library that ensures only one instance of your application is running at a time.

License NuGet NuGet Downloads Build Status GitHub Stars

Introduction

ktsu.SingleAppInstance is a lightweight .NET library that provides a robust mechanism to ensure only one instance of an application is running at a time. This is essential for desktop applications, services, or any software that requires instance exclusivity to prevent resource conflicts, maintain data integrity, or provide a consistent user experience.

Features

  • Single Instance Enforcement: Ensures only one instance of the application is running
  • Enhanced Process Identification: Uses multiple attributes (PID, name, start time, executable path) for accurate identification
  • Race Condition Handling: Manages potential conflicts when instances start simultaneously
  • PID File Management: Stores process information securely in the application data directory
  • Cross-Platform Support: Works on Windows, macOS, and Linux
  • Backward Compatibility: Maintains compatibility with older versions that only stored the PID
  • Simple API: Clean, easy-to-use interface with just two primary methods

Installation

Package Manager Console

Install-Package ktsu.SingleAppInstance

.NET CLI

dotnet add package ktsu.SingleAppInstance

Package Reference

<PackageReference Include="ktsu.SingleAppInstance" Version="x.y.z" />

Usage Examples

Basic Example

The simplest way to use SingleAppInstance is to call the ExitIfAlreadyRunning method at the start of your application:

using ktsu.SingleAppInstance;

class Program
{
    static void Main(string[] args)
    {
        SingleAppInstance.ExitIfAlreadyRunning();
        
        // Your application code here
        Console.WriteLine("Application is running.");
    }
}

Custom Launch Logic

If you prefer to explicitly handle the case where another instance is already running:

using ktsu.SingleAppInstance;

class Program
{
    static void Main(string[] args)
    {
        if (SingleAppInstance.ShouldLaunch())
        {
            // Your application code here
            Console.WriteLine("Application is running.");
        }
        else
        {
            // Handle the case where another instance is already running
            Console.WriteLine("Another instance is already running.");
            
            // Optional: Activate the existing window, pass command-line arguments, etc.
        }
    }
}

Advanced Usage

WPF Application Integration

using System.Windows;
using ktsu.SingleAppInstance;

namespace MyWpfApp
{
    public partial class App : Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            
            if (!SingleAppInstance.ShouldLaunch())
            {
                // Another instance is already running
                MessageBox.Show("Application is already running.");
                Shutdown();
                return;
            }
            
            // Continue with normal startup
            MainWindow = new MainWindow();
            MainWindow.Show();
        }
    }
}

Console Application with Command Passing

For a more complex scenario where you want to pass commands to an existing instance:

using System;
using ktsu.SingleAppInstance;

class Program
{
    static void Main(string[] args)
    {
        // Check if we can launch
        if (!SingleAppInstance.ShouldLaunch())
        {
            // Another instance is already running
            // Here you could implement an IPC mechanism to pass arguments to the running instance
            Console.WriteLine("Another instance is already running. Sending arguments...");
            
            // Example: Using named pipes, TCP, or memory-mapped files to communicate
            // SendArgsToRunningInstance(args);
            
            return;
        }
        
        // We're the primary instance
        Console.WriteLine("Application is running.");
        
        // Optional: Setup your IPC listening mechanism
        // SetupIpcListener();
        
        // Application main loop
        Console.ReadLine();
    }
}

API Reference

SingleAppInstance Class

The static class that provides instance management functionality.

Methods
Name Return Type Description
ExitIfAlreadyRunning() void Exits the application with a status code of 0 if another instance is already running
ShouldLaunch() bool Determines whether the application should launch based on whether another instance is running

Technical Implementation

Under the hood, SingleAppInstance:

  1. Stores a JSON-serialized ProcessInfo object containing:

    • Process ID
    • Process name
    • Start time
    • Main module filename

  2. Uses the application data directory to store the PID file. The file is named .SingleAppInstance.pid.

  3. When checking for running instances, it:

    • Reads the PID file
    • Verifies if a process with the stored ID exists
    • Confirms it's the same application by comparing process name and executable path
    • Handles access restrictions and various edge cases

  4. Implements a 1-second timeout in ShouldLaunch() to detect race conditions when multiple instances start simultaneously.

Contributing

Contributions are welcome! Here's how you can help:

  1. Fork the repository
  2. Create your feature branch (git checkout -b feature/amazing-feature)
  3. Commit your changes (git commit -m 'Add some amazing feature')
  4. Push to the branch (git push origin feature/amazing-feature)
  5. Open a Pull Request

Please make sure to update tests as appropriate and adhere to the existing coding style.

License

This project is licensed under the MIT License - see the LICENSE.md file for details.

Product Compatible and additional computed target framework versions.
.NET net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 is compatible.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last Updated
1.2.6-pre.18 116 5/20/2025
1.2.6-pre.15 72 5/17/2025
1.2.6-pre.14 127 5/16/2025
1.2.6-pre.13 196 5/15/2025
1.2.6-pre.12 194 5/14/2025
1.2.6-pre.11 194 5/13/2025
1.2.6-pre.10 227 5/12/2025
1.2.6-pre.9 164 5/11/2025
1.2.6-pre.8 104 5/10/2025
1.2.6-pre.7 46 5/9/2025
1.2.6-pre.6 117 5/8/2025
1.2.6-pre.5 117 5/7/2025
1.2.6-pre.4 114 5/6/2025
1.2.6-pre.3 114 5/5/2025
1.2.6-pre.2 116 5/4/2025
1.2.6-pre.1 111 5/4/2025
1.2.5 145 5/4/2025
1.2.5-pre.3 107 4/29/2025
1.2.5-pre.2 128 4/28/2025
1.2.5-pre.1 61 4/26/2025
1.2.4 141 4/25/2025
1.2.3 111 4/19/2025
1.2.2 176 4/18/2025
1.2.2-pre.3 60 4/4/2025
1.2.2-pre.2 113 4/4/2025
1.2.2-pre.1 132 3/31/2025
1.2.1 147 3/30/2025
1.2.0 149 3/30/2025
1.1.1-pre.2 74 3/29/2025
1.1.1-pre.1 462 3/25/2025
1.1.0 119 2/17/2025
1.0.0-pre.19 71 2/14/2025
1.0.0-pre.18 72 2/6/2025
1.0.0-pre.17 68 2/5/2025
1.0.0-pre.16 61 2/5/2025
1.0.0-pre.15 69 2/3/2025
1.0.0-pre.14 70 2/3/2025
1.0.0-pre.13 62 2/3/2025
1.0.0-pre.12 78 2/2/2025
1.0.0-pre.11 65 1/31/2025
1.0.0-pre.10 63 1/30/2025
1.0.0-pre.9 75 1/28/2025
1.0.0-pre.8 64 1/26/2025
1.0.0-pre.7 58 1/24/2025
1.0.0-pre.6 65 1/22/2025
1.0.0-pre.5 65 1/20/2025
1.0.0-pre.4 57 1/18/2025
1.0.0-pre.3 58 1/16/2025
1.0.0-pre.2 43 1/14/2025
1.0.0-pre.1 65 1/13/2025
0.0.1-pre.1 58 1/13/2025

## v1.2.5 (patch)

Changes since v1.2.4:

- Remove .markdownlint.json configuration file, update DESCRIPTION.md for clarity, and change project SDK references in .csproj files to ktsu.Sdk.Lib and ktsu.Sdk.Test version 1.8.0. ([@matt-edmondson](https://github.com/matt-edmondson))
- Remove Directory.Build.props, Directory.Build.targets, and several PowerShell scripts for metadata and version management. Update SingleAppInstance and its tests to use 'var' for variable declarations and add copyright information. ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.2.5-pre.3 (prerelease)

Changes since v1.2.5-pre.2:

- Bump ktsu.AppDataStorage from 1.11.0 to 1.15.0 in the ktsu group ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.2.5-pre.2 (prerelease)

Changes since v1.2.5-pre.1:

- Bump ktsu.AppDataStorage from 1.7.2 to 1.11.0 in the ktsu group ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.2.5-pre.1 (prerelease)

Changes since v1.2.4:

- Sync .github\workflows\dotnet.yml ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync .editorconfig ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.2.4 (patch)

Changes since v1.2.3:

- Update README to match standard template format ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.2.3 (patch)

Changes since v1.2.2:

- Add tests for SingleAppInstance behavior with no other instance running and custom launch logic ([@matt-edmondson](https://github.com/matt-edmondson))
- Enhance SingleAppInstance to store and verify process information in JSON format ([@matt-edmondson](https://github.com/matt-edmondson))
- Enhance memory.jsonl to include advanced process detection and compatibility details for SingleAppInstance class ([@matt-edmondson](https://github.com/matt-edmondson))
- Refine README.md for clarity and usage instructions of SingleAppInstance ([@matt-edmondson](https://github.com/matt-edmondson))
- Update language-specific guidelines to clarify test execution commands and improve resource management ([@matt-edmondson](https://github.com/matt-edmondson))
- Refine README.md to enhance feature descriptions and clarify technical implementation details for SingleAppInstance ([@matt-edmondson](https://github.com/matt-edmondson))
- Set max cpus for tests to 1 ([@matt-edmondson](https://github.com/matt-edmondson))
- Add memory.jsonl file with project and class details ([@matt-edmondson](https://github.com/matt-edmondson))
- Update test command to run in a single process ([@matt-edmondson](https://github.com/matt-edmondson))
- Enhance memory.jsonl to include additional details for SingleAppInstance tests and project structure ([@matt-edmondson](https://github.com/matt-edmondson))
- Refactor SingleAppInstanceTests to simplify file deletion logic and remove unnecessary try-finally blocks, ensuring clearer test flow and improved readability. ([@matt-edmondson](https://github.com/matt-edmondson))
- Update Copilot instructions for .NET project build and testing guidelines ([@matt-edmondson](https://github.com/matt-edmondson))
- Refactor SingleAppInstanceTests for better isolation ([@matt-edmondson](https://github.com/matt-edmondson))
- Organize and enhance Copilot documentation with detailed guidelines on memory usage, coding standards, and project management practices. ([@matt-edmondson](https://github.com/matt-edmondson))
- Refine workflow guidelines for clarity on specialized tool usage and documentation checks ([@matt-edmondson](https://github.com/matt-edmondson))
- Add SingleAppInstance.Test project to solution and configure build settings ([@matt-edmondson](https://github.com/matt-edmondson))
- Refactor SingleAppInstanceTests to improve clarity and structure of test methods, ensuring accurate PID file handling and process information validation. ([@matt-edmondson](https://github.com/matt-edmondson))
- Update language-specific guidelines to clarify tool usage and fallback options ([@matt-edmondson](https://github.com/matt-edmondson))
- Add workflow and process guidelines to Copilot instructions ([@matt-edmondson](https://github.com/matt-edmondson))
- Comment out MaxCpuCount setting in .runsettings to disable process-level parallelization ([@matt-edmondson](https://github.com/matt-edmondson))
- Clarify command line usage by providing an example for non-interactive mode with `git` commands ([@matt-edmondson](https://github.com/matt-edmondson))
- Enhance SingleAppInstanceTests by adding assertions to verify PID file handling and initial state checks ([@matt-edmondson](https://github.com/matt-edmondson))
- Add guidelines for using command line in non-interactive mode and directory context ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.2.2 (patch)

Changes since v1.2.1:

- Add comprehensive Copilot instructions and memory management guidelines ([@matt-edmondson](https://github.com/matt-edmondson))
- Add markdownlint configuration file for linting rules ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.2.2-pre.3 (prerelease)

Changes since v1.2.2-pre.2:

- Bump ktsu.AppDataStorage from 1.7.1 to 1.7.2 in the ktsu group ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.2.2-pre.2 (prerelease)

Changes since v1.2.2-pre.1:

- Sync .editorconfig ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.2.2-pre.1 (prerelease)

Incremental prerelease update.
## v1.2.1 (patch)

Changes since v1.2.0:

- Update packages ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.2.0 (minor)

Changes since v1.1.0:

- Add LICENSE template ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.1.1-pre.2 (prerelease)

Changes since v1.1.1-pre.1:

- Sync scripts\make-changelog.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync scripts\make-version.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.1.1-pre.1 (prerelease)

Changes since v1.1.0:

- Sync .editorconfig ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync scripts\make-changelog.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync .gitignore ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync Directory.Build.targets ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync scripts\make-version.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.1.0 (minor)

Changes since v1.0.0-pre.19:

- Apply new editorconfig ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.0.0-pre.19 (prerelease)

Changes since v1.0.0-pre.18:

- Bump ktsu.AppDataStorage from 1.4.7 to 1.5.0 in the ktsu group ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.0.0-pre.18 (prerelease)

Changes since v1.0.0-pre.17:

- Sync scripts\make-version.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync scripts\make-changelog.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.0.0-pre.17 (prerelease)

Changes since v1.0.0-pre.16:

- Sync .github\workflows\dotnet.yml ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.0.0-pre.16 (prerelease)

Changes since v1.0.0-pre.15:

- Sync scripts\make-changelog.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
- Sync scripts\make-version.ps1 ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.0.0-pre.15 (prerelease)

Changes since v1.0.0-pre.14:

- Sync .github\workflows\dotnet.yml ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.0.0-pre.14 (prerelease)

Changes since v1.0.0-pre.13:

- Review Feedback ([@Damon3000s](https://github.com/Damon3000s))
- Revert unintended changes ([@Damon3000s](https://github.com/Damon3000s))
- Create the directory the Pid will be stored in ([@Damon3000s](https://github.com/Damon3000s))
## v1.0.0-pre.13 (prerelease)

Changes since v1.0.0-pre.12:

- Sync .github\workflows\dotnet.yml ([@ktsu[bot]](https://github.com/ktsu[bot]))
## v1.0.0-pre.12 (prerelease)

Changes since v1.0.0-pre.11:
## v1.0.0-pre.11 (prerelease)

Changes since v1.0.0-pre.10:
## v1.0.0-pre.10 (prerelease)

Changes since v1.0.0-pre.9:

- Catch DirectoryNotFoundException ([@Damon3000s](https://github.com/Damon3000s))
## v1.0.0-pre.9 (prerelease)

Changes since v1.0.0-pre.8:

- Bump MSTest from 3.7.2 to 3.7.3 ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.0.0-pre.8 (prerelease)

Changes since v1.0.0-pre.7:
## v1.0.0-pre.7 (prerelease)

Changes since v1.0.0-pre.6:
## v1.0.0-pre.6 (prerelease)

Changes since v1.0.0-pre.5:

- Bump MSTest from 3.7.1 to 3.7.2 ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.0.0-pre.5 (prerelease)

Changes since v1.0.0-pre.4:

- Bump coverlet.collector from 6.0.3 to 6.0.4 ([@dependabot[bot]](https://github.com/dependabot[bot]))
## v1.0.0-pre.4 (prerelease)

Changes since v1.0.0-pre.3:
## v1.0.0-pre.3 (prerelease)

Changes since v1.0.0-pre.2:
## v1.0.0-pre.2 (prerelease)

Changes since v1.0.0-pre.1:

- Remove ktsu.ScopedAction package from project ([@matt-edmondson](https://github.com/matt-edmondson))
## v1.0.0-pre.1 (prerelease)

Incremental prerelease update.
## v0.0.1-pre.1 (prerelease)

Incremental prerelease update.