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Find the instances of an executable in the system path, in C#.

Quick start

Install the latest version of Which for .NET with NuGet package manager:

dotnet add package Belin.Which

For detailed instructions, see the installation guide.

Usage

This package provides the Finder.Which(string command) method, allowing to locate a command in the system path.
This method takes the name of the command to locate, and returns a ResultSet instance.

The ResultSet class implements the IEnumerable<string> interface.
It is therefore possible to iterate over the results using a foreach loop:

using System;
using static Belin.Which.Finder;

// Finds all instances of an executable and returns them one at a time.
Console.WriteLine("The 'foobar' command is available at these locations:");
foreach (var path in Which("foo")) Console.WriteLine($"- {path}");

The ResultSet class also provides two convenient properties:

• All : get all instances of the searched command.
• First : get the first instance of the searched command.

string[] All

The ResultSet.All property returns an array of the absolute paths of all instances of an executable found in the system path. If the executable could not be located, it returns an empty array.

using System;
using static Belin.Which.Finder;

var paths = Which("foobar").All;
if (paths.Length == 0) Console.Error.WriteLine("The 'foobar' command cannot be found.");
else {
  Console.WriteLine("The 'foobar' command is available at these locations:");
  foreach (var path in paths) Console.WriteLine($"- {path}");
}

string? First

The ResultSet.First property returns the absolute path of the first instance of an executable found in the system path. If the executable could not be located, it returns a null reference.

using System;
using static Belin.Which.Finder;

var path = Which("foobar").First;
if (path is null) Console.Error.WriteLine("The 'foobar' command cannot be found.");
else Console.WriteLine($"The 'foobar' command is located at: {path}");

Options

The behavior of the Finder.Which(string command, IEnumerable<string>? paths = null, IEnumerable<string>? extensions = null) method can be customized using the following parameters.

IEnumerable<string> extensions

An enumerable of strings specifying the list of executable file extensions. On Windows, defaults to the list of extensions provided by the PATHEXT environment variable.

Which("foobar", extensions: [".foo", ".exe", ".cmd"]);

Note

The extensions option is only meaningful on the Windows platform, where the executability of a file is determined from its extension.

IEnumerable<string> paths

An enumerable of strings specifying the system paths from which the given command will be searched. Defaults to the list of directories provided by the PATH environment variable.

Which("foobar", paths: ["/usr/local/bin", "/usr/bin"]);