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doc/build-helpers: refactor the paragraph about runCommandLocal

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nicoo
2024-08-19 19:16:43 +00:00
parent e3d7e7f2a7
commit 2b8a6a7e43
1 changed files with 14 additions and 13 deletions
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doc/build-helpers/trivial-build-helpers.chapter.md
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@@ -29,11 +29,12 @@ runCommandWith :: {
: The derivation's name, which Nix will append to the store path; see [`mkDerivation`](#sec-using-stdenv).
`runLocal` (Boolean)
: If set to `true` this forces the derivation to be built locally. Remote substitutes and distributed builds, won't be used.
: If set to `true` this forces the derivation to be built locally, not using [substitutes] nor remote builds.
This is intended for very cheap commands (<1s execution time) which can be sped up by avoiding the network round-trip(s).
Its effect is to set [`preferLocalBuild = true`][preferLocalBuild] and [`allowSubstitutes = false`][allowSubstitutes].
::: {.note}
This prevents the use of substitutors, so only set `runLocal` (or use `runCommandLocal`) when certain the user will
This prevents the use of [substituters][substituter], so only set `runLocal` (or use `runCommandLocal`) when certain the user will
always have a builder for the `system` of the derivation. This should be true for most trivial use cases
(e.g., just copying some files to a different location or adding symlinks) because there the `system`
is usually the same as `builtins.currentSystem`.
@@ -54,6 +55,8 @@ runCommandWith :: {
[allowSubstitutes]: https://nixos.org/nix/manual/#adv-attr-allowSubstitutes
[preferLocalBuild]: https://nixos.org/nix/manual/#adv-attr-preferLocalBuild
[substituter]: https://nix.dev/manual/nix/latest/glossary#gloss-substituter
[substitutes]: https://nix.dev/manual/nix/2.23/glossary#gloss-substitute
::: {.example #ex-runcommandwith}
# Invocation of `runCommandWith`
@@ -80,16 +83,22 @@ The function `runCommand` returns a derivation built using the specified command
`runCommandCC` is similar but uses the default compiler environment. To minimize dependencies, `runCommandCC`
should only be used when the build command needs a C compiler.
`runCommandLocal` is also similar to `runCommand`, but forces the derivation to be built locally.
See the note on [`runCommandWith`] about `runLocal`.
[`runCommandWith`]: #trivial-builder-runCommandWith
### Type {#trivial-builder-runCommand-Type}
```
runCommand :: String -> AttrSet -> String -> Derivation
runCommandCC :: String -> AttrSet -> String -> Derivation
runCommand :: String -> AttrSet -> String -> Derivation
runCommandCC :: String -> AttrSet -> String -> Derivation
runCommandLocal :: String -> AttrSet -> String -> Derivation
```
### Input {#trivial-builder-runCommand-Input}
While the type signature(s) differ from `runCommandWith`, individual arguments with the same name will have the same type and meaning:
While the type signature(s) differ from [`runCommandWith`], individual arguments with the same name will have the same type and meaning:
`name` (String)
: The derivation's name
@@ -144,14 +153,6 @@ runCommandWith {
:::
## `runCommandLocal` {#trivial-builder-runCommandLocal}
Variant of `runCommand` that forces the derivation to be built locally, it is not substituted. This is intended for very cheap commands (<1s execution time). It saves on the network round-trip and can speed up a build.
::: {.note}
This sets [`allowSubstitutes` to `false`][allowSubstitutes], so only use `runCommandLocal` if you are certain the user will always have a builder for the `system` of the derivation. This should be true for most trivial use cases (e.g., just copying some files to a different location or adding symlinks) because there the `system` is usually the same as `builtins.currentSystem`.
:::
## Writing text files {#trivial-builder-text-writing}
Nixpkgs provides the following functions for producing derivations which write text files or executable scripts into the Nix store.