SmolFennec.SpeCLI 1.2.0

.NET Standard 2.0
Install-Package SmolFennec.SpeCLI -Version 1.2.0
dotnet add package SmolFennec.SpeCLI --version 1.2.0
<PackageReference Include="SmolFennec.SpeCLI" Version="1.2.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add SmolFennec.SpeCLI --version 1.2.0
The NuGet Team does not provide support for this client. Please contact its maintainers for support.
#r "nuget: SmolFennec.SpeCLI, 1.2.0"
#r directive can be used in F# Interactive, C# scripting and .NET Interactive. Copy this into the interactive tool or source code of the script to reference the package.
// Install SmolFennec.SpeCLI as a Cake Addin
#addin nuget:?package=SmolFennec.SpeCLI&version=1.2.0

// Install SmolFennec.SpeCLI as a Cake Tool
#tool nuget:?package=SmolFennec.SpeCLI&version=1.2.0
The NuGet Team does not provide support for this client. Please contact its maintainers for support.


SmolFennec is a collective name for small libraries and tools released by Levi licensed under MIT and hosted on github. SpeCLI provides a way to describe CLI behaviour of external processes.

<img src="" width="300" height="300">

NuGet version (SmolFennec.SpeCLI)


Supported platforms: .Net Standard 2.0+

When in trouble: Submit an issue


EZ mode:

(The ping command was used below for short instructional purposes, ofcourse it is not meant to be used like this, use the ping class instead!)

Create a class for input and a class for output. Usable attributes:

  • Parameter: Defines a parameter with name and value, like: -n 50
  • Switch: Defines a switch with name only, like: -6
  • HideName: Defines a parameter with value only, like: Hostname
  • When nothing is supplied a parameter with the property name and a value is created
class PingArguments
    public bool Continuous { get; set; }
    public int? Count { get; set; }
    public int? TTL { get; set; }
    public int? Timeout { get; set; }
    public bool IPV4 { get; set; }
    public bool IPV6 { get; set; }
    public string Host { get; set; }

class PingResult
    public string ip { get; set; }
    public string fail { get; set; }
    public bool Success => !string.IsNullOrEmpty(ip) && string.IsNullOrEmpty(fail);
    public int bytes { get; set; }
    public TimeSpan time { get; set; }
    public int ttl { get; set; }

Create an Executable with Commands Usable OutputProcessors at this time:

  • JsonOutputProcessor: Parses the outputted lines as json
  • RegexCaptureOutputProcessor: Populates an object with matched regex groups
  • RegexSplitOutputProcessor: Splits the lines matching regexes over different OutputProcessors
  • CloneOutputProcessor: Clones the output and sends it to other OutputProcessors
  • Interface to write your own!

For the individual configuration please look at the configuration properties and methods.

 // The regex we will use later
const string regex = @"Reply from (?<ip>[^:]+): (?:bytes=(?<bytes>\d+) time[^\d]*(?<time>[^ ]+) TTL=(?<ttl>\d+)|(?<fail>.+))";
 // Create an executable to hold commands to be reused
var exe = new Executable("ping");
 // Add a new command
     // Add all parameters from this type
         // Use this processor to handle regex output
        new RegexCaptureOutputProcessor()
         // Map this regex to the output type we made, this can be done multiple times
        .AddRegex<PingResult>(new Regex(regex))
         // Add a manual mapping for the non-standard timespan conversion
        .AddPropertyMapping(s => TimeSpan.FromMilliseconds(int.Parse(s.TrimEnd('m', 's'))))

Use the constructed Executable:

List<PingResult> matches = exe.ExecuteCommandAndParseList<PingResult>("ping", new PingArguments() {
    Count = 8,
    Host = "Hostname",
    Timeout = 50

Full sample can be found in the source.

Manual/Advanced mode:

IAsyncEnumerables can be obtained like this:

var iae = exe.ExecuteCommandAndParseIAsyncEnumerable<PingResult>("ping", new PingArguments() { Host = "Hostname" });

Parameters can also be declared manually. When invoking a nameless type, a Dictionary<string, object> or another type with similar properties can also be used. When you specify a List<object> any objects generated from whatever type will be returned

    .AddParameter(new Parameter<string>("host").WithHideName());
    .AddParameter(new Switch("6"))

var objs = exe.ExecuteCommandAndParseList<object>("ping", new { Host = "Hostname" });

An Execution object can also be obtained, altho short-lived (pun intended) these can allow more low-level access to the process, events and Stdin.

var exec = exe.CreateExecution("ping", new PingArguments() { Host = "Hostname" });
exec.OutputDataReceived += (s, e) => { }; // raw stdout
exec.ErrorDataReceived += (s, e) => { }; // raw stderr
exec.OnOutput += (s, e) => { }; // Parsed objects
exec.OnError += (s, e) => { }; // Exceptions during parsing
exec.Start(); // Needs to be started manually;
exec.SendInputLine("Hello World!"); // Can send stdin



Define Arguments and results exactly like normal SpeCLI configuration. Create a Executable class:

  • Enter path to executable or the command in the Executable attribute
  • Inherit from IExecutable to add an OnConfiguring method to apply further configuration during proxy generation
  • Add any OutputProcessors in the OnConfiguring method
public abstract class Ping : IExecutable
    public void OnConfiguring(Executable executable)
        var processor = new RegexCaptureOutputProcessor()
            .AddRegex<PingResult>(new Regex(@"Reply from (?<ip>[^:]+): (?:bytes=(?<bytes>\d+) time[^\d]*(?<time>[^ ]+) TTL=(?<ttl>\d+)|(?<fail>.+))"))
            .AddPropertyMapping((string s) => !string.IsNullOrEmpty(s) ? TimeSpan.FromMilliseconds(int.Parse(s.TrimEnd('m', 's'))) : (TimeSpan?)null);
        foreach (var command in executable.Commands)
            command.Processor = processor;

Configure commands in these steps:

  • Add Command attribute to a public abstract method with or without custom name
  • Add a supported return type: any object supported by selected OutputProcessors or a List<> or IAsyncEnumerable<> of that object, or an Execution object
  • Add arguments for your parameters:
    • a single defined object containing parameter attributes (like ping/PingArguments)
    • a set of parameters with their attributes (like ping2)
    • an object or Dictionary<string, object> ⇒ need to add parameter attributes to the method (like ping3/4)
  • Adding parameters can be done on the method and defaults can be assigned without adding them as parameter if you want to make a specific method for a certain CLI option (like SinglePing)


public abstract List<PingResult> ping(PingArguments arguments);
public abstract List<PingResult> ping2([Switch("t")] bool Continuous, [Parameter("n")] int? Count, [Parameter("w")] int? Timeout, [HideName] string Host);
[Parameter("Host", HideName = true)]
public abstract List<PingResult> ping3(object arguments);
[Parameter("Host", HideName = true)]
public abstract List<PingResult> ping4(Dictionary<string, object> arguments);
[Parameter("n", typeof(int?), 1)]
public abstract PingResult SinglePing([HideName] string Host, [Parameter("w")] int? Timeout = null);
[Parameter("n", typeof(int?), 1)]
public abstract Execution SinglePingExecution([HideName] string Host, [Parameter("w")] int? Timeout = null);

In your code make and use the proxy like this:

var ping = SpeCLIProxy.Create<Ping>();
var matches = PingArguments() { Count = pings, Host = "", Timeout = 50 });

This will run the CLI and parse the output all automatically, providing a strongly typed interface to a CLI you only need to configure once.

Product Versions
.NET net5.0 net5.0-windows net6.0 net6.0-android net6.0-ios net6.0-maccatalyst net6.0-macos net6.0-tvos net6.0-windows
.NET Core netcoreapp2.0 netcoreapp2.1 netcoreapp2.2 netcoreapp3.0 netcoreapp3.1
.NET Standard netstandard2.0 netstandard2.1
.NET Framework net461 net462 net463 net47 net471 net472 net48
MonoAndroid monoandroid
MonoMac monomac
MonoTouch monotouch
Tizen tizen40 tizen60
Xamarin.iOS xamarinios
Xamarin.Mac xamarinmac
Xamarin.TVOS xamarintvos
Xamarin.WatchOS xamarinwatchos
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

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Version Downloads Last updated
1.2.0 273 1/3/2021
1.1.4 371 1/3/2021
1.1.3 248 12/30/2020
1.1.2 317 12/22/2020
1.1.1 256 12/21/2020
1.1.0 199 12/21/2020
1.0.0 217 11/10/2020

Added exception options for throwing and aborting parsing in execution and command
Commands keep their own name
IExecutionConfigurator now passes command and arguments