42 lines
979 B
Markdown
42 lines
979 B
Markdown
# Package from Source
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This note covers `17-package-from-source/`, which packages a selected local source tree and excludes unrelated files from the build input.
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---
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## 1. Why Source Selection Matters
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`src = ./.;` copies the whole example directory into the store. That is fine for small demos, but real packages often need a narrower source tree.
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This example uses `lib.fileset.toSource` so the derivation only sees:
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- `src/run.sh`, and
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- `src/message.txt`.
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That leaves `ignored.txt` out of the packaged source on purpose.
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---
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## 2. Why the Check Looks at the Source Path
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The check does two things:
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- it runs the packaged binary, and
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- it asserts that the generated source path does not contain `ignored.txt`.
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That keeps the example focused on the real behavior being taught: selecting build inputs, not just producing a runnable script.
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---
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## 3. Commands to Try
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```bash
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cd 17-package-from-source
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nix build
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./result/bin/source-greet
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nix run
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nix flake check
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```
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