My Shell Scripts Speak C# Now

Every couple of weeks I need a twenty-line program. Find what's bloating a build agent's disk, dedupe a CSV, hash-check a folder. For fifteen years the honest answer to "which language?" was not C# — by the time I'd done mkdir , dotnet new console , and named yet another throwaway csproj, the moment had passed. So those little jobs went to bash or Python, and I grumbled quietly every time. .NET 10 removed the ritual. You write one .cs file and run it. I'd been meaning to check how well this actually holds up for real scripts, so this week I did — nothing fancy, one Linux container and a stopwatch. One file, no project Here's biggest.cs , a small utility that lists the largest files under a directory. The whole program is this one file — no csproj anywhere: # !/ usr / bin / env dotnet # : package Humanizer @ 3.0 . 10 using Humanizer ; var root = args . Length > 0 ? args [ 0 ] : "." ; var top = args . Length > 1 && int . TryParse ( args [ 1 ], out var n ) ? n : 10 ; var files = new DirectoryInfo ( root ) . EnumerateFiles ( "*" , new EnumerationOptions { RecurseSubdirectories = true , IgnoreInaccessible = true , AttributesToSkip = FileAttributes . ReparsePoint }) . OrderByDescending ( f => f . Length ) . Take ( top ) . ToList (); foreach ( var f in files ) { var size = f . Length . Bytes (). Humanize ( "#.#" ); var age = ( DateTime . UtcNow - f . LastWriteTimeUtc ). Humanize (); Console . WriteLine ( $" { size , 10 } { f . FullName } (modified { age } ago)" ); } Two lines are new. #:package Humanizer@3.0.10 is a NuGet reference written as a directive, right in the source. The shebang we'll get to in a minute. Everything else is the C# you already write, top-level statements and all. $ dotnet run biggest.cs -- ~/.dotnet 5 Top 5 files under /root/.dotnet: 37.6 MB .../FSharp.Compiler.Service.dll (modified 46 seconds ago) 18.7 MB .../Microsoft.CodeAnalysis.CSharp.dll (modified 46 seconds ago) 18.7 MB .../Roslyn/bincore/Microsoft.CodeAnalysis.CSharp.dll (modified 45 seconds