C# Process
last modified July 5, 2023
In this article, we explore how to work with processes in C# using the
System.Diagnostics namespace.
The Process class provides access to both local and remote
processes, allowing developers to start, stop, monitor, and interact with system
processes. Whether it's launching an external application, capturing process
output, or managing running tasks, the Process class offers a
comprehensive set of functionalities.
To configure process execution, C# provides the ProcessStartInfo
class, which specifies various settings such as:
- FileName: Defines the executable or command to run.
- Arguments: Passes command-line arguments to the process.
- UseShellExecute: Determines whether to use the system shell to start the process.
- RedirectStandardOutput: Enables capturing the process output.
- CreateNoWindow: Specifies whether to run the process in a hidden window.
The Process class is part of the System.Diagnostics
namespace, which contains various tools for debugging, monitoring, and
performance analysis.
With the ability to start, manage, and terminate system processes, C# developers can efficiently interact with external applications, automate tasks, and analyze system activity.
C# Process simple example
In the first example, we start a console command that shows the contents of a file.
using System.Diagnostics;
Process.Start("cat", @"C:\Users\Jano\Documents\words.txt");
The example outputs the contents of the words.txt file with
the cat command. The command is not part of the Windows OS by
default; it is installed with the git tools (see gitforwindows.org).
Process.Start("cat", @"C:\Users\Jano\Documents\words.txt");
The process is started with the Start method.
$ dotnet run sky cloud falcon owl crane
C# Process run program
In the following example, we run a GUI program.
using System.Diagnostics; using var process = new Process(); process.StartInfo.FileName = "notepad.exe"; process.Start();
In the example, we run the Notepad program. It is a standard, small text editor.
process.StartInfo.FileName = "notepad.exe";
The StartInfo.FileName property bets or sets the application or
document to start.
using System.Diagnostics; using var process = new Process(); process.StartInfo.FileName = "notepad.exe"; process.StartInfo.Arguments = @"C:\Users\Jano\Documents\words.txt"; process.Start();
We use the StartInfo.Arguments to pass the file name to be opened.
C# start and kill program
The next example starts a program and kills it after a few seconds.
using System.Diagnostics;
using var process = Process.Start("notepad.exe");
Thread.Sleep(3000);
process.Kill();
The example starts Notepad, sleeps for three seconds and kills the process
with the Kill method.
C# Process.GetProcessesByName
The Process.GetProcessesByName creates an array of new Process
components and associates them with the existing process resources that all
share the specified process name.
using System.Diagnostics;
Process[] processes = Process.GetProcessesByName("Firefox");
Console.WriteLine("{0} Firefox processes", processes.Length);
Array.ForEach(processes, (process) =>
{
Console.WriteLine("Process: {0} Id: {1}",
process.ProcessName, process.Id);
});
In the example, we find all processes belonging to the Firefox. We list their Ids and process names.
Process[] processes = Process.GetProcessesByName("Firefox");
We get the array of processes by the name of "Firefox".
Console.WriteLine("{0} Firefox processes", processes.Length);
We print the number of processes found.
Array.ForEach(processes, (process) =>
{
Console.WriteLine("Process: {0} Id: {1}",
process.ProcessName, process.Id);
});
We list the processes with the ForEach method.
$ dotnet run 12 Firefox processes Process: firefox Id: 10056 Process: firefox Id: 13016 Process: firefox Id: 12944 Process: firefox Id: 10124 Process: firefox Id: 15556 ...
C# Process.GetProcesses
The Process.GetProcesses creates an array of new Process
components and associates them with existing process resources.
using System.Diagnostics;
Process[] processes = Process.GetProcesses();
Array.ForEach(processes, (process) =>
{
Console.WriteLine("Process: {0} Id: {1}",
process.ProcessName, process.Id);
});
The example list all processes.
Process[] processes = Process.GetProcesses();
We get the array of processes.
Array.ForEach(processes, (process) =>
{
Console.WriteLine("Process: {0} Id: {1}",
process.ProcessName, process.Id);
});
We iterate over the array and print the process names and Ids.
C# Process redirect output
The StandardOutput property gets a stream used to read the textual
output of the application.
using System.Diagnostics;
var psi = new ProcessStartInfo();
psi.FileName = "ls";
psi.UseShellExecute = false;
psi.RedirectStandardOutput = true;
using var process = Process.Start(psi);
using StreamReader reader = process.StandardOutput;
string data = reader.ReadToEnd();
File.WriteAllText("output.txt", data);
In the example, we redirect the output of the ls command to the
output.txt file.
psi.UseShellExecute = false; psi.RedirectStandardOutput = true;
Setting the UseShellExecute to false enables us to
redirect input, output, and error streams. (In this context, the shell refers
to the graphical shell rather than command shell such as bash or sh.)
using var process = Process.Start(psi);
We start the process with the provided info.
using StreamReader reader = process.StandardOutput;
We get the StreamReader for the standard output.
string data = reader.ReadToEnd();
We read all data with the ReadToEnd method.
File.WriteAllText("output.txt", data);
Finally, we write the data to the file.
Source
Process class - language reference
In this article we have worked with processes in C#.
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