csharp-scripts

Name: csharp-scripts
Author: wshaddix

65stars10forks

How to install csharp-scripts?

wshaddix/dotnet-skills/csharp-scripts

$npx -y skills add wshaddix/dotnet-skills --skill csharp-scripts

Installs into the current project.

Summary

Run single-file C# programs as scripts for quick experimentation, prototyping, and concept testing. Use when the user wants to write and execute a small C# program without creating a full project.

Files · 1

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SKILL.md

1	# C# Scripts
2
3	## When to Use
4
5	- Testing a C# concept, API, or language feature with a quick one-file program
6	- Prototyping logic before integrating it into a larger project
7
8	## When Not to Use
9
10	- The user needs a full project with multiple files or project references
11	- The user is working inside an existing .NET solution and wants to add code there
12	- The program is too large or complex for a single file
13
14	## Inputs
15
16	\| Input \| Required \| Description \|
17	\|-------\|----------\|-------------\|
18	\| C# code or intent \| Yes \| The code to run, or a description of what the script should do \|
19
20	## Workflow
21
22	### Step 1: Check the .NET SDK version
23
24	Run `dotnet --version` to verify the SDK is installed and note the major version number. File-based apps require .NET 10 or later. If the version is below 10, follow the [fallback for older SDKs](#fallback-for-net-9-and-earlier) instead.
25
26	### Step 2: Write the script file
27
28	Create a single `.cs` file using top-level statements. Place it outside any existing project directory to avoid conflicts with `.csproj` files.
29
30	```csharp
31	// hello.cs
32	Console.WriteLine("Hello from a C# script!");
33
34	var numbers = new[] { 1, 2, 3, 4, 5 };
35	Console.WriteLine($"Sum: {numbers.Sum()}");
36	```
37
38	Guidelines:
39
40	- Use top-level statements (no `Main` method, class, or namespace boilerplate)
41	- Place `using` directives at the top of the file
42	- Place type declarations (classes, records, enums) after all top-level statements
43
44	### Step 3: Run the script
45
46	```bash
47	dotnet hello.cs
48	```
49
50	Builds and runs the file automatically. Cached so subsequent runs are fast. Pass arguments after `--`:
51
52	```bash
53	dotnet hello.cs -- arg1 arg2 "multi word arg"
54	```
55
56	### Step 4: Add NuGet packages (if needed)
57
58	Use the `#:package` directive at the top of the file to reference NuGet packages. Always specify a version:
59
60	```csharp
61	#:package Humanizer@2.14.1
62
63	using Humanizer;
64
65	Console.WriteLine("hello world".Titleize());
66	```
67
68	### Step 5: Clean up
69
70	Remove the script file when the user is done. To clear cached build artifacts:
71
72	```bash
73	dotnet clean hello.cs
74	```
75
76	## Unix shebang support
77
78	On Unix platforms, make a `.cs` file directly executable:
79
80	1. Add a shebang as the first line of the file:
81
82	```csharp
83	#!/usr/bin/env dotnet
84	Console.WriteLine("I'm executable!");
85	```
86
87	2. Set execute permissions:
88
89	```bash
90	chmod +x hello.cs
91	```
92
93	3. Run directly:
94
95	```bash
96	./hello.cs
97	```
98
99	Use `LF` line endings (not `CRLF`) when adding a shebang. This directive is ignored on Windows.
100
101	## Source-generated JSON
102
103	File-based apps enable native AOT by default. Reflection-based APIs like `JsonSerializer.Serialize<T>(value)` fail at runtime under AOT. Use source-generated serialization instead:
104
105	```csharp
106	using System.Text.Json;
107	using System.Text.Json.Serialization;
108
109	var person = new Person("Alice", 30);
110	var json = JsonSerializer.Serialize(person, AppJsonContext.Default.Person);
111	Console.WriteLine(json);
112
113	var deserialized = JsonSerializer.Deserialize(json, AppJsonContext.Default.Person);
114	Console.WriteLine($"Name: {deserialized!.Name}, Age: {deserialized.Age}");
115
116	record Person(string Name, int Age);
117
118	[JsonSerializable(typeof(Person))]
119	partial class AppJsonContext : JsonSerializerContext;
120	```
121
122	## Converting to a project
123
124	When a script outgrows a single file, convert it to a full project:
125
126	```bash
127	dotnet project convert hello.cs
128	```
129
130	## Fallback for .NET 9 and earlier
131
132	If the .NET SDK version is below 10, file-based apps are not available. Use a temporary console project instead:
133
134	```bash
135	mkdir -p /tmp/csharp-script && cd /tmp/csharp-script
136	dotnet new console -o . --force
137	```
138
139	Replace the generated `Program.cs` with the script content and run with `dotnet run`. Add NuGet packages with `dotnet add package <name>`. Remove the directory when done.
140
141	## Validation
142
143	- [ ] `dotnet --version` reports 10.0 or later (or fallback path is used)
144	- [ ] The script compiles without errors (can be checked explicitly with `dotnet build <file>.cs`)
145	- [ ] `dotnet <file>.cs` produces the expected output
146	- [ ] Script file and cached artifacts are cleaned up after the session
147
148	## Common Pitfalls
149
150	\| Pitfall \| Solution \|
151	\|---------\|----------\|
152	\| `.cs` file is inside a directory with a `.csproj` \| Move the script outside the project directory, or use `dotnet run --file file.cs` \|
153	\| `#:package` without a version \| Specify a version: `#:package PackageName@1.2.3` or `@*` for latest \|
154	\| Reflection-based JSON serialization fails \| Use source-generated JSON with `JsonSerializerContext` (see [Source-generated JSON](#source-generated-json)) \|
155	\| Unexpected build behavior or version errors \| File-based apps inherit `global.json`, `Directory.Build.props`, `Directory.Build.targets`, and `nuget.config` from parent directories. Move the script to an

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Type

csharp-scripts

65stars10forks

View on GitHub

How to install csharp-scripts?

wshaddix/dotnet-skills/csharp-scripts

$npx -y skills add wshaddix/dotnet-skills --skill csharp-scripts

Installs into the current project.

Summary

Run single-file C# programs as scripts for quick experimentation, prototyping, and concept testing. Use when the user wants to write and execute a small C# program without creating a full project.

Files · 1

View on GitHub

SKILL.md

1	# C# Scripts
2
3	## When to Use
4
5	- Testing a C# concept, API, or language feature with a quick one-file program
6	- Prototyping logic before integrating it into a larger project
7
8	## When Not to Use
9
10	- The user needs a full project with multiple files or project references
11	- The user is working inside an existing .NET solution and wants to add code there
12	- The program is too large or complex for a single file
13
14	## Inputs
15
16	\| Input \| Required \| Description \|
17	\|-------\|----------\|-------------\|
18	\| C# code or intent \| Yes \| The code to run, or a description of what the script should do \|
19
20	## Workflow
21
22	### Step 1: Check the .NET SDK version
23
24	Run `dotnet --version` to verify the SDK is installed and note the major version number. File-based apps require .NET 10 or later. If the version is below 10, follow the [fallback for older SDKs](#fallback-for-net-9-and-earlier) instead.
25
26	### Step 2: Write the script file
27
28	Create a single `.cs` file using top-level statements. Place it outside any existing project directory to avoid conflicts with `.csproj` files.
29
30	```csharp
31	// hello.cs
32	Console.WriteLine("Hello from a C# script!");
33
34	var numbers = new[] { 1, 2, 3, 4, 5 };
35	Console.WriteLine($"Sum: {numbers.Sum()}");
36	```
37
38	Guidelines:
39
40	- Use top-level statements (no `Main` method, class, or namespace boilerplate)
41	- Place `using` directives at the top of the file
42	- Place type declarations (classes, records, enums) after all top-level statements
43
44	### Step 3: Run the script
45
46	```bash
47	dotnet hello.cs
48	```
49
50	Builds and runs the file automatically. Cached so subsequent runs are fast. Pass arguments after `--`:
51
52	```bash
53	dotnet hello.cs -- arg1 arg2 "multi word arg"
54	```
55
56	### Step 4: Add NuGet packages (if needed)
57
58	Use the `#:package` directive at the top of the file to reference NuGet packages. Always specify a version:
59
60	```csharp
61	#:package Humanizer@2.14.1
62
63	using Humanizer;
64
65	Console.WriteLine("hello world".Titleize());
66	```
67
68	### Step 5: Clean up
69
70	Remove the script file when the user is done. To clear cached build artifacts:
71
72	```bash
73	dotnet clean hello.cs
74	```
75
76	## Unix shebang support
77
78	On Unix platforms, make a `.cs` file directly executable:
79
80	1. Add a shebang as the first line of the file:
81
82	```csharp
83	#!/usr/bin/env dotnet
84	Console.WriteLine("I'm executable!");
85	```
86
87	2. Set execute permissions:
88
89	```bash
90	chmod +x hello.cs
91	```
92
93	3. Run directly:
94
95	```bash
96	./hello.cs
97	```
98
99	Use `LF` line endings (not `CRLF`) when adding a shebang. This directive is ignored on Windows.
100
101	## Source-generated JSON
102
103	File-based apps enable native AOT by default. Reflection-based APIs like `JsonSerializer.Serialize<T>(value)` fail at runtime under AOT. Use source-generated serialization instead:
104
105	```csharp
106	using System.Text.Json;
107	using System.Text.Json.Serialization;
108
109	var person = new Person("Alice", 30);
110	var json = JsonSerializer.Serialize(person, AppJsonContext.Default.Person);
111	Console.WriteLine(json);
112
113	var deserialized = JsonSerializer.Deserialize(json, AppJsonContext.Default.Person);
114	Console.WriteLine($"Name: {deserialized!.Name}, Age: {deserialized.Age}");
115
116	record Person(string Name, int Age);
117
118	[JsonSerializable(typeof(Person))]
119	partial class AppJsonContext : JsonSerializerContext;
120	```
121
122	## Converting to a project
123
124	When a script outgrows a single file, convert it to a full project:
125
126	```bash
127	dotnet project convert hello.cs
128	```
129
130	## Fallback for .NET 9 and earlier
131
132	If the .NET SDK version is below 10, file-based apps are not available. Use a temporary console project instead:
133
134	```bash
135	mkdir -p /tmp/csharp-script && cd /tmp/csharp-script
136	dotnet new console -o . --force
137	```
138
139	Replace the generated `Program.cs` with the script content and run with `dotnet run`. Add NuGet packages with `dotnet add package <name>`. Remove the directory when done.
140
141	## Validation
142
143	- [ ] `dotnet --version` reports 10.0 or later (or fallback path is used)
144	- [ ] The script compiles without errors (can be checked explicitly with `dotnet build <file>.cs`)
145	- [ ] `dotnet <file>.cs` produces the expected output
146	- [ ] Script file and cached artifacts are cleaned up after the session
147
148	## Common Pitfalls
149
150	\| Pitfall \| Solution \|
151	\|---------\|----------\|
152	\| `.cs` file is inside a directory with a `.csproj` \| Move the script outside the project directory, or use `dotnet run --file file.cs` \|
153	\| `#:package` without a version \| Specify a version: `#:package PackageName@1.2.3` or `@*` for latest \|
154	\| Reflection-based JSON serialization fails \| Use source-generated JSON with `JsonSerializerContext` (see [Source-generated JSON](#source-generated-json)) \|
155	\| Unexpected build behavior or version errors \| File-based apps inherit `global.json`, `Directory.Build.props`, `Directory.Build.targets`, and `nuget.config` from parent directories. Move the script to an

People who liked this also viewed

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Type