Elycin / MedallionShell

A .NET library simplifying the execution and chaining of processes

MedallionShell

MedallionShell is a lightweight library that vastly simplifies working with processes in .NET apps.

Download the NuGet package

Built on top of the powerful, yet clunky System.Diagnostics.Process API, the MedallionShell API streamlines common use-cases, removes pitfalls, and integrates Process handling with .NET async/await and Tasks.

// processes are created and interacted with using the Command class
var cmd = Command.Run("path_to_grep", "some REGEX");
cmd.StandardInput.PipeFromAsync(new FileInfo("some path"));
// by default, all output streams are buffered, so there's no need to worry
// about deadlock
var outputLines = cmd.StandardOutput.GetLines().ToList();
var errorText = cmd.StandardError.ReadToEnd();

// by default, the underlying Process is automatically disposed 
// so no using block is required

// and complex arguments are automatically escaped
var cmd = Command.Run("path_to_grep", "\\ some \"crazy\" REGEX \\");

// we can also do this inline using bash-style operator overloads
var lines = new List<string>();
var cmd = Command.Run("path_to_grep", "some REGEX") < new FileInfo("some path") > lines;
cmd.Wait();

// and we can even chain commands together with the pipe operator
var pipeline = Command.Run("path_to_grep", "some REGEX") | Command.Run("path_to_grep", "another REGEX");

// if you don't like using operators, you can use the equivalent fluent methods instead
var cmd = Command.Run("path_to_grep", some REGEX").RedirectFrom(new FileInfo("some path")).RedirectTo(lines);

// we can check a command's exit status using it's result
if (cmd.Result.Success) { ... }

// and perform async operations via its associated task
await cmd.Task;

// commands are also highly configurable
var cmd = Command.Run(
	"path_to_grep",
	new[] { "some REGEX" },	
	options: o => o
		// arbitrarily configure the ProcessStartInfo
		.StartInfo(si => si.RedirectStandardError = false)
		// option to turn a non-zero exit code into an exception
		.ThrowOnError()
		// option to kill the command and throw TimeoutException if it doesn't finish
		.Timeout(TimeSpan.FromMinutes(1))
		...
);

// and if we want to keep using a common set of configuration options, we 
// can package them up in a Shell object
var shell = new Shell(o => o.ThrowOnError()...);
shell.Run("path_to_grep", "some REGEX");

Cross-Platform Support

MedallionShell makes it easier to write process-handling code that works across different .NET platforms.

In particular, Mono has peculiarities in how it handles writing to an exited process that makes it very difficult to write correct cross-platform code. MedallionShell contains workarounds for these oddities that help ensure that code that works on .NET Framework/.NET Core runs seamlessly on Mono (see #6 and #22).

Release Notes

• 1.5.1 Improves Mono.Android compatibility (#22). Thanks sushihangover for reporting and testing the fix!
• 1.5.0
  • Command overrides ToString() to simplify debugging (#19). Thanks Stephanvs!
  • WindowsCommandLineSyntax no longer quotes arguments that don't require it
• 1.4.0
  • Adds cancellation support (#18)
  • Adds API for getting the underlying process ID for a command even with the DisposeOnExit option (#16)
  • Adds API for consuming standard out and standard error lines together as a single stream (#14)
  • Improves Mono compatibility (#6)
  • Changes Command.Result and Command.Wait() to throw unwrapped exceptions instead of AggregateException
• 1.3.0 Fixes default standard IO stream encodings (thanks xjfnet!) and added support for specifying a custom encoding
• 1.2.1 Adds .NET Core support (thanks kal!), adds new fluent APIs for each of the piping/redirection operators, and now respects StandardInput.AutoFlush when piping between commands
• 1.1.0 Adds AutoFlush support to StandardInput, and fixed bug where small amounts of flushed data became "stuck" in the StandardOutput buffer
• 1.0.3 Fixes bug with standard error (thanks nsdfxela!)
• 1.0.2 Fixes bug where timeout would suppress errors from ThrowOnError option
• 1.0.1 Allows for argument ommission in Command.Run(), other minor fixes
• 1.0.0 Initial release

Building The Code

You will need VisualStudio 2017 or higher (community edition is fine) download.