How to Spawn a Process in C# (With Code Examples)

Spawning a process in C# is a powerful technique that lets your application interact with external programs, scripts, or tools. Whether you’re launching Notepad, running a batch file, or executing a command-line utility, C# gives you full control through the System.Diagnostics namespace.

In this guide, you’ll learn how to start a process in C#, pass arguments, capture output, and handle errors. We’ll go step-by-step with practical examples.

What Does It Mean to Spawn a Process in C#?

In programming, spawning a process means launching another application or script from your own program. In C#, this is typically done using the System.Diagnostics.Process class.

The simplest way to start a process is with Process.Start(), but for more advanced scenarios—like redirecting output or running background commands—you’ll use ProcessStartInfo.

Basic Example: Launching Notepad

Let’s start with a simple example: opening Notepad from a C# application.

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using System.Diagnostics;

 

Process.Start(“notepad.exe”);

This line opens Notepad using the default application settings. This is the simplest use case—no arguments, no output redirection.

Running a Process With Arguments

You might want to run a program with custom parameters. For example, let’s run an executable and pass options to it:

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using System.Diagnostics;

 

var process = new Process();

process.StartInfo.FileName = “example.exe”;

process.StartInfo.Arguments = “-option1 value1 -flag”;

process.Start();

This launches example.exe and passes two arguments: -option1 value1 and -flag.

💡 Tip: If your file paths or arguments contain spaces, wrap them in quotes.

Redirecting Output and Error Streams

Sometimes, you want to capture the output of a process—especially when running command-line tools.

Here’s how to do it:

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var process = new Process();

process.StartInfo.FileName = “cmd.exe”;

process.StartInfo.Arguments = “/c dir”;

process.StartInfo.RedirectStandardOutput = true;

process.StartInfo.RedirectStandardError = true;

process.StartInfo.UseShellExecute = false;

 

process.OutputDataReceived += (sender, args) => Console.WriteLine(args.Data);

process.ErrorDataReceived += (sender, args) => Console.WriteLine(“ERROR: ” + args.Data);

 

process.Start();

process.BeginOutputReadLine();

process.BeginErrorReadLine();

process.WaitForExit();

This example runs the Windows dir command and prints the output (or any error) to the console.

Waiting for the Process to Exit

If your application depends on the completion of a process before continuing, use WaitForExit():

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process.WaitForExit();

This ensures that your program pauses until the process finishes running.

Handling Errors and Exceptions

Always wrap your process code in a try/catch block. This helps you handle errors gracefully, such as when the executable isn’t found.

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try

{

    Process.Start(“nonexistent.exe”);

}

catch (Exception ex)

{

    Console.WriteLine(“Failed to start process: ” + ex.Message);

}

Real-World Use Cases

Here are some common reasons to spawn a process in C#:

• Running PowerShell or Bash scripts.
• Automating build tools or deployment tasks.
• Launching utilities like git, ffmpeg, or curl.
• Opening URLs or files using the default system handler.

Troubleshooting Tips

• Process closes immediately? Make sure the command isn’t executing and exiting too quickly. Try running it in a terminal first.
• Getting “The system cannot find the file specified”? Double-check the file path and filename.
• Using arguments with spaces? Use quotes in your argument string (e.g., “\”C:\\Program Files\\App\\app.exe\“”).

Frequently Asked Questions

Can I run Linux commands from a C# app?

Yes, on Linux systems you can run commands via /bin/bash -c “command” using ProcessStartInfo.

Is Process.Start() asynchronous?

Yes, the process starts in the background, and your code continues unless you call WaitForExit().

Can I kill a running process?

Yes. Once you’ve started it and have a reference, call process.Kill().

Conclusion

Spawning a process in C# opens the door to automation, integration, and customization. Whether you’re building a tool or enhancing an application, knowing how to start, monitor, and control processes gives you a ton of flexibility.

Want to dive deeper? Check out the official System.Diagnostics.Process documentation.