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Diffstat (limited to 'doc')
-rw-r--r-- | doc/builders/trivial-builders.chapter.md | 52 | ||||
-rw-r--r-- | doc/builders/trivial-builders.xml | 90 | ||||
-rw-r--r-- | doc/manual.xml | 2 |
3 files changed, 53 insertions, 91 deletions
diff --git a/doc/builders/trivial-builders.chapter.md b/doc/builders/trivial-builders.chapter.md new file mode 100644 index 000000000000..c39803fbe339 --- /dev/null +++ b/doc/builders/trivial-builders.chapter.md @@ -0,0 +1,52 @@ +# Trivial builders {#chap-trivial-builders} + +Nixpkgs provides a couple of functions that help with building derivations. The most important one, `stdenv.mkDerivation`, has already been documented above. The following functions wrap `stdenv.mkDerivation`, making it easier to use in certain cases. + +## `runCommand` {#trivial-builder-runCommand} + +This takes three arguments, `name`, `env`, and `buildCommand`. `name` is just the name that Nix will append to the store path in the same way that `stdenv.mkDerivation` uses its `name` attribute. `env` is an attribute set specifying environment variables that will be set for this derivation. These attributes are then passed to the wrapped `stdenv.mkDerivation`. `buildCommand` specifies the commands that will be run to create this derivation. Note that you will need to create `$out` for Nix to register the command as successful. + +An example of using `runCommand` is provided below. + +```nix +(import <nixpkgs> {}).runCommand "my-example" {} '' + echo My example command is running + + mkdir $out + + echo I can write data to the Nix store > $out/message + + echo I can also run basic commands like: + + echo ls + ls + + echo whoami + whoami + + echo date + date +'' +``` + +## `runCommandCC` {#trivial-builder-runCommandCC} + +This works just like `runCommand`. The only difference is that it also provides a C compiler in `buildCommand`'s environment. To minimize your dependencies, you should only use this if you are sure you will need a C compiler as part of running your command. + +## `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 roundrip and can speed up a build. + +::: {.note} +This sets [`allowSubstitutes` to `false`](https://nixos.org/nix/manual/#adv-attr-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`. +::: + +## `writeTextFile`, `writeText`, `writeTextDir`, `writeScript`, `writeScriptBin` {#trivial-builder-writeText} + +These functions write `text` to the Nix store. This is useful for creating scripts from Nix expressions. `writeTextFile` takes an attribute set and expects two arguments, `name` and `text`. `name` corresponds to the name used in the Nix store path. `text` will be the contents of the file. You can also set `executable` to true to make this file have the executable bit set. + +Many more commands wrap `writeTextFile` including `writeText`, `writeTextDir`, `writeScript`, and `writeScriptBin`. These are convenience functions over `writeTextFile`. + +## `symlinkJoin` {#trivial-builder-symlinkJoin} + +This can be used to put many derivations into the same directory structure. It works by creating a new derivation and adding symlinks to each of the paths listed. It expects two arguments, `name`, and `paths`. `name` is the name used in the Nix store path for the created derivation. `paths` is a list of paths that will be symlinked. These paths can be to Nix store derivations or any other subdirectory contained within. diff --git a/doc/builders/trivial-builders.xml b/doc/builders/trivial-builders.xml deleted file mode 100644 index 94948c57b91f..000000000000 --- a/doc/builders/trivial-builders.xml +++ /dev/null @@ -1,90 +0,0 @@ -<chapter xmlns="http://docbook.org/ns/docbook" - xmlns:xlink="http://www.w3.org/1999/xlink" - xmlns:xi="http://www.w3.org/2001/XInclude" - xml:id="chap-trivial-builders"> - <title>Trivial builders</title> - <para> - Nixpkgs provides a couple of functions that help with building derivations. The most important one, <function>stdenv.mkDerivation</function>, has already been documented above. The following functions wrap <function>stdenv.mkDerivation</function>, making it easier to use in certain cases. - </para> - <variablelist> - <varlistentry xml:id="trivial-builder-runCommand"> - <term> - <literal>runCommand</literal> - </term> - <listitem> - <para> - This takes three arguments, <literal>name</literal>, <literal>env</literal>, and <literal>buildCommand</literal>. <literal>name</literal> is just the name that Nix will append to the store path in the same way that <literal>stdenv.mkDerivation</literal> uses its <literal>name</literal> attribute. <literal>env</literal> is an attribute set specifying environment variables that will be set for this derivation. These attributes are then passed to the wrapped <literal>stdenv.mkDerivation</literal>. <literal>buildCommand</literal> specifies the commands that will be run to create this derivation. Note that you will need to create <literal>$out</literal> for Nix to register the command as successful. - </para> - <para> - An example of using <literal>runCommand</literal> is provided below. - </para> -<programlisting> -(import <nixpkgs> {}).runCommand "my-example" {} '' - echo My example command is running - - mkdir $out - - echo I can write data to the Nix store > $out/message - - echo I can also run basic commands like: - - echo ls - ls - - echo whoami - whoami - - echo date - date -'' -</programlisting> - </listitem> - </varlistentry> - <varlistentry xml:id="trivial-builder-runCommandCC"> - <term> - <literal>runCommandCC</literal> - </term> - <listitem> - <para> - This works just like <literal>runCommand</literal>. The only difference is that it also provides a C compiler in <literal>buildCommand</literal>’s environment. To minimize your dependencies, you should only use this if you are sure you will need a C compiler as part of running your command. - </para> - </listitem> - </varlistentry> - <varlistentry xml:id="trivial-builder-runCommandLocal"> - <term> - <literal>runCommandLocal</literal> - </term> - <listitem> - <para> - Variant of <literal>runCommand</literal> 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 roundrip and can speed up a build. - </para> - <note><para> - This sets <link xlink:href="https://nixos.org/nix/manual/#adv-attr-allowSubstitutes"><literal>allowSubstitutes</literal> to <literal>false</literal></link>, so only use <literal>runCommandLocal</literal> if you are certain the user will always have a builder for the <literal>system</literal> 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 <literal>system</literal> is usually the same as <literal>builtins.currentSystem</literal>. - </para></note> - </listitem> - </varlistentry> - <varlistentry xml:id="trivial-builder-writeText"> - <term> - <literal>writeTextFile</literal>, <literal>writeText</literal>, <literal>writeTextDir</literal>, <literal>writeScript</literal>, <literal>writeScriptBin</literal> - </term> - <listitem> - <para> - These functions write <literal>text</literal> to the Nix store. This is useful for creating scripts from Nix expressions. <literal>writeTextFile</literal> takes an attribute set and expects two arguments, <literal>name</literal> and <literal>text</literal>. <literal>name</literal> corresponds to the name used in the Nix store path. <literal>text</literal> will be the contents of the file. You can also set <literal>executable</literal> to true to make this file have the executable bit set. - </para> - <para> - Many more commands wrap <literal>writeTextFile</literal> including <literal>writeText</literal>, <literal>writeTextDir</literal>, <literal>writeScript</literal>, and <literal>writeScriptBin</literal>. These are convenience functions over <literal>writeTextFile</literal>. - </para> - </listitem> - </varlistentry> - <varlistentry xml:id="trivial-builder-symlinkJoin"> - <term> - <literal>symlinkJoin</literal> - </term> - <listitem> - <para> - This can be used to put many derivations into the same directory structure. It works by creating a new derivation and adding symlinks to each of the paths listed. It expects two arguments, <literal>name</literal>, and <literal>paths</literal>. <literal>name</literal> is the name used in the Nix store path for the created derivation. <literal>paths</literal> is a list of paths that will be symlinked. These paths can be to Nix store derivations or any other subdirectory contained within. - </para> - </listitem> - </varlistentry> - </variablelist> -</chapter> diff --git a/doc/manual.xml b/doc/manual.xml index 4367c023b402..eb14dbb440d1 100644 --- a/doc/manual.xml +++ b/doc/manual.xml @@ -24,7 +24,7 @@ <part> <title>Builders</title> <xi:include href="builders/fetchers.xml" /> - <xi:include href="builders/trivial-builders.xml" /> + <xi:include href="builders/trivial-builders.chapter.xml" /> <xi:include href="builders/special.xml" /> <xi:include href="builders/images.xml" /> <xi:include href="languages-frameworks/index.xml" /> |