Fix some dangling references

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Eelco Dolstra 2020-07-24 14:31:33 +02:00
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23 changed files with 139 additions and 235 deletions

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@ -1,33 +1,32 @@
# Tuning Cores and Jobs # Tuning Cores and Jobs
Nix has two relevant settings with regards to how your CPU cores will be Nix has two relevant settings with regards to how your CPU cores will
utilized: [???](#conf-cores) and [???](#conf-max-jobs). This chapter be utilized: `cores` and `max-jobs`. This chapter will talk about what
will talk about what they are, how they interact, and their they are, how they interact, and their configuration trade-offs.
configuration trade-offs.
- [???](#conf-max-jobs) - `max-jobs`
Dictates how many separate derivations will be built at the same Dictates how many separate derivations will be built at the same
time. If you set this to zero, the local machine will do no builds. time. If you set this to zero, the local machine will do no
Nix will still substitute from binary caches, and build remotely if builds. Nix will still substitute from binary caches, and build
remote builders are configured. remotely if remote builders are configured.
- [???](#conf-cores) - `cores`
Suggests how many cores each derivation should use. Similar to `make Suggests how many cores each derivation should use. Similar to
-j`. `make -j`.
The [???](#conf-cores) setting determines the value of The `cores` setting determines the value of
`NIX_BUILD_CORES`. `NIX_BUILD_CORES` is equal to [???](#conf-cores), `NIX_BUILD_CORES`. `NIX_BUILD_CORES` is equal to `cores`, unless
unless [???](#conf-cores) equals `0`, in which case `NIX_BUILD_CORES` `cores` equals `0`, in which case `NIX_BUILD_CORES` will be the total
will be the total number of cores in the system. number of cores in the system.
The maximum number of consumed cores is a simple multiplication, The maximum number of consumed cores is a simple multiplication,
[???](#conf-max-jobs) \* `NIX_BUILD_CORES`. `max-jobs` \* `NIX_BUILD_CORES`.
The balance on how to set these two independent variables depends upon The balance on how to set these two independent variables depends upon
each builder's workload and hardware. Here are a few example scenarios each builder's workload and hardware. Here are a few example scenarios
on a machine with 24 cores: on a machine with 24 cores:
| [???](#conf-max-jobs) | [???](#conf-cores) | `NIX_BUILD_CORES` | Maximum Processes | Result | | `max-jobs` | `cores` | `NIX_BUILD_CORES` | Maximum Processes | Result |
| --------------------- | ------------------ | ----------------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | --------------------- | ------------------ | ----------------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 1 | 24 | 24 | 24 | One derivation will be built at a time, each one can use 24 cores. Undersold if a job cant use 24 cores. | | 1 | 24 | 24 | 24 | One derivation will be built at a time, each one can use 24 cores. Undersold if a job cant use 24 cores. |
| 4 | 6 | 6 | 24 | Four derivations will be built at once, each given access to six cores. | | 4 | 6 | 6 | 24 | Four derivations will be built at once, each given access to six cores. |
@ -35,8 +34,6 @@ on a machine with 24 cores:
| 24 | 1 | 1 | 24 | 24 derivations can build at the same time, each using a single core. Never oversold, but derivations which require many cores will be very slow to compile. | | 24 | 1 | 1 | 24 | 24 derivations can build at the same time, each using a single core. Never oversold, but derivations which require many cores will be very slow to compile. |
| 24 | 0 | 24 | 576 | 24 derivations can build at the same time, each using all the available cores of the machine. Very likely to be oversold, and very likely to suffer context switches. | | 24 | 0 | 24 | 576 | 24 derivations can build at the same time, each using all the available cores of the machine. Very likely to be oversold, and very likely to suffer context switches. |
Balancing 24 Build Cores
It is up to the derivations' build script to respect host's requested It is up to the derivations' build script to respect host's requested
cores-per-build by following the value of the `NIX_BUILD_CORES` cores-per-build by following the value of the `NIX_BUILD_CORES`
environment variable. environment variable.

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@ -1,9 +1,8 @@
# Verifying Build Reproducibility # Verifying Build Reproducibility
Specify a program with Nix's [???](#conf-diff-hook) to compare build You can use Nix's `diff-hook` setting to compare build results. Note
results when two builds produce different results. Note: this hook is that this hook is only executed if the results differ; it is not used
only executed if the results are not the same, this hook is not used for for determining if the results are the same.
determining if the results are the same.
For purposes of demonstration, we'll use the following Nix file, For purposes of demonstration, we'll use the following Nix file,
`deterministic.nix` for testing: `deterministic.nix` for testing:
@ -93,7 +92,7 @@ has copied the build results to that directory where you can examine it.
> path will be deleted on the next garbage collection. > path will be deleted on the next garbage collection.
> >
> The path is guaranteed to be alive for the duration of > The path is guaranteed to be alive for the duration of
> [???](#conf-diff-hook)'s execution, but may be deleted any time after. > the `diff-hook`'s execution, but may be deleted any time after.
> >
> If the comparison is performed as part of automated tooling, please > If the comparison is performed as part of automated tooling, please
> use the diff-hook or author your tooling to handle the case where the > use the diff-hook or author your tooling to handle the case where the
@ -112,9 +111,8 @@ Run the build without `--check`, and then try with `--check` again.
Automatically verify every build at build time by executing the build Automatically verify every build at build time by executing the build
multiple times. multiple times.
Setting [???](#conf-repeat) and [???](#conf-enforce-determinism) in your Setting `repeat` and `enforce-determinism` in your `nix.conf` permits
`nix.conf` permits the automated verification of every build Nix the automated verification of every build Nix performs.
performs.
The following configuration will run each build three times, and will The following configuration will run each build three times, and will
require the build to be deterministic: require the build to be deterministic:
@ -122,9 +120,9 @@ require the build to be deterministic:
enforce-determinism = true enforce-determinism = true
repeat = 2 repeat = 2
Setting [???](#conf-enforce-determinism) to false as in the following Setting `enforce-determinism` to false as in the following
configuration will run the build multiple times, execute the build hook, configuration will run the build multiple times, execute the build
but will allow the build to succeed even if it does not build hook, but will allow the build to succeed even if it does not build
reproducibly: reproducibly:
enforce-determinism = false enforce-determinism = false

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@ -17,9 +17,8 @@ the build loop.
# Prerequisites # Prerequisites
This tutorial assumes you have configured an S3-compatible binary cache This tutorial assumes you have [configured an S3-compatible binary
according to the instructions at cache](../package-management/s3-substituter.md), and that the `root`
[???](#ssec-s3-substituter-authenticated-writes), and that the `root`
user's default AWS profile can upload to the bucket. user's default AWS profile can upload to the bucket.
# Set up a Signing Key # Set up a Signing Key
@ -33,7 +32,7 @@ distribute the public key for verifying the authenticity of the paths.
example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=
Then, add the public key and the cache URL to your `nix.conf`'s Then, add the public key and the cache URL to your `nix.conf`'s
[???](#conf-trusted-public-keys) and [???](#conf-substituters) like: `trusted-public-keys` and `substituters` options:
substituters = https://cache.nixos.org/ s3://example-nix-cache substituters = https://cache.nixos.org/ s3://example-nix-cache
trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM= trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=

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@ -77,8 +77,7 @@ The following settings are currently available:
--optimise` to get rid of duplicate files. --optimise` to get rid of duplicate files.
- `builders` - `builders`
A list of machines on which to perform builds. See A list of machines on which to perform builds.
[???](#chap-distributed-builds) for details.
- `builders-use-substitutes` - `builders-use-substitutes`
If set to `true`, Nix will instruct remote build machines to use If set to `true`, Nix will instruct remote build machines to use
@ -141,8 +140,6 @@ The following settings are currently available:
command line switch and defaults to `1`. The value `0` means that command line switch and defaults to `1`. The value `0` means that
the builder should use all available CPU cores in the system. the builder should use all available CPU cores in the system.
See also [???](#chap-tuning-cores-and-jobs).
- `diff-hook` - `diff-hook`
Absolute path to an executable capable of diffing build results. The Absolute path to an executable capable of diffing build results. The
hook executes if [varlistentry\_title](#conf-run-diff-hook) is true, hook executes if [varlistentry\_title](#conf-run-diff-hook) is true,
@ -299,8 +296,6 @@ The following settings are currently available:
regardless). It can be overridden using the `--max-jobs` (`-j`) regardless). It can be overridden using the `--max-jobs` (`-j`)
command line switch. command line switch.
See also [???](#chap-tuning-cores-and-jobs).
- `max-silent-time` - `max-silent-time`
This option defines the maximum number of seconds that a builder can This option defines the maximum number of seconds that a builder can
go without producing any data on standard output or standard error. go without producing any data on standard output or standard error.
@ -429,12 +424,10 @@ The following settings are currently available:
Example: Example:
`/nix/store/zf5lbh336mnzf1nlswdn11g4n2m8zh3g-bash-4.4-p23-dev `/nix/store/zf5lbh336mnzf1nlswdn11g4n2m8zh3g-bash-4.4-p23-dev
/nix/store/rjxwxwv1fpn9wa2x5ssk5phzwlcv4mna-bash-4.4-p23-doc /nix/store/rjxwxwv1fpn9wa2x5ssk5phzwlcv4mna-bash-4.4-p23-doc
/nix/store/6bqvbzjkcp9695dq0dpl5y43nvy37pq1-bash-4.4-p23-info /nix/store/6bqvbzjkcp9695dq0dpl5y43nvy37pq1-bash-4.4-p23-info
/nix/store/r7fng3kk3vlpdlh2idnrbn37vh4imlj2-bash-4.4-p23-man /nix/store/r7fng3kk3vlpdlh2idnrbn37vh4imlj2-bash-4.4-p23-man
/nix/store/xfghy8ixrhz3kyy6p724iv3cxji088dx-bash-4.4-p23`. /nix/store/xfghy8ixrhz3kyy6p724iv3cxji088dx-bash-4.4-p23`.
See [???](#chap-post-build-hook) for an example implementation.
- `repeat` - `repeat`
How many times to repeat builds to check whether they are How many times to repeat builds to check whether they are
@ -459,8 +452,7 @@ The following settings are currently available:
`allowed-uri`. The default is `false`. `allowed-uri`. The default is `false`.
- `run-diff-hook` - `run-diff-hook`
If true, enable the execution of If true, enable the execution of the `diff-hook` program.
[varlistentry\_title](#conf-diff-hook).
When using the Nix daemon, `run-diff-hook` must be set in the When using the Nix daemon, `run-diff-hook` must be set in the
`nix.conf` configuration file, and cannot be passed at the command `nix.conf` configuration file, and cannot be passed at the command
@ -595,15 +587,11 @@ The following settings are currently available:
Nix will print a log message at the "vomit" level for every function Nix will print a log message at the "vomit" level for every function
entrance and function exit. entrance and function exit.
<div class="informalexample">
function-trace entered undefined position at 1565795816999559622 function-trace entered undefined position at 1565795816999559622
function-trace exited undefined position at 1565795816999581277 function-trace exited undefined position at 1565795816999581277
function-trace entered /nix/store/.../example.nix:226:41 at 1565795253249935150 function-trace entered /nix/store/.../example.nix:226:41 at 1565795253249935150
function-trace exited /nix/store/.../example.nix:226:41 at 1565795253249941684 function-trace exited /nix/store/.../example.nix:226:41 at 1565795253249941684
</div>
The `undefined position` means the function call is a builtin. The `undefined position` means the function call is a builtin.
Use the `contrib/stack-collapse.py` script distributed with the Nix Use the `contrib/stack-collapse.py` script distributed with the Nix

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@ -46,7 +46,7 @@ expression to a low-level store derivation) and [`nix-store
All options not listed here are passed to `nix-store All options not listed here are passed to `nix-store
--realise`, except for `--arg` and `--attr` / `-A` which are passed to --realise`, except for `--arg` and `--attr` / `-A` which are passed to
`nix-instantiate`. See also [???](#sec-common-options). `nix-instantiate`.
- `--no-out-link` - `--no-out-link`
Do not create a symlink to the output path. Note that as a result Do not create a symlink to the output path. Note that as a result

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@ -13,7 +13,6 @@ Title: nix-channel
A Nix channel is a mechanism that allows you to automatically stay A Nix channel is a mechanism that allows you to automatically stay
up-to-date with a set of pre-built Nix expressions. A Nix channel is up-to-date with a set of pre-built Nix expressions. A Nix channel is
just a URL that points to a place containing a set of Nix expressions. just a URL that points to a place containing a set of Nix expressions.
See also [???](#sec-channels).
To see the list of official NixOS channels, visit To see the list of official NixOS channels, visit
<https://nixos.org/channels>. <https://nixos.org/channels>.

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@ -66,7 +66,7 @@ match. Here are some examples:
This section lists the options that are common to all operations. These This section lists the options that are common to all operations. These
options are allowed for every subcommand, though they may not always options are allowed for every subcommand, though they may not always
have an effect. See also [???](#sec-common-options). have an effect.
- `--file` / `-f` *path* - `--file` / `-f` *path*
Specifies the Nix expression (designated below as the *active Nix Specifies the Nix expression (designated below as the *active Nix

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@ -30,8 +30,6 @@ the resulting store derivations are printed on standard output.
If *files* is the character `-`, then a Nix expression will be read from If *files* is the character `-`, then a Nix expression will be read from
standard input. standard input.
See also [???](#sec-common-options) for a list of common options.
# Options # Options
- `--add-root` *path*; `--indirect` - `--add-root` *path*; `--indirect`

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@ -50,7 +50,7 @@ will cause `nix-shell` to print `Hello shell`.
All options not listed here are passed to `nix-store All options not listed here are passed to `nix-store
--realise`, except for `--arg` and `--attr` / `-A` which are passed to --realise`, except for `--arg` and `--attr` / `-A` which are passed to
`nix-instantiate`. See also [???](#sec-common-options). `nix-instantiate`.
- `--command` *cmd* - `--command` *cmd*
In the environment of the derivation, run the shell command *cmd*. In the environment of the derivation, run the shell command *cmd*.

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@ -23,16 +23,15 @@ subcommand to be performed. These are documented below.
This section lists the options that are common to all operations. These This section lists the options that are common to all operations. These
options are allowed for every subcommand, though they may not always options are allowed for every subcommand, though they may not always
have an effect. See also [???](#sec-common-options) for a list of common have an effect.
options.
- `--add-root` *path* - `--add-root` *path*
Causes the result of a realisation (`--realise` and Causes the result of a realisation (`--realise` and
`--force-realise`) to be registered as a root of the garbage `--force-realise`) to be registered as a root of the garbage
collector(see [???](#ssec-gc-roots)). The root is stored in *path*, collector. The root is stored in *path*, which must be inside a
which must be inside a directory that is scanned for roots by the directory that is scanned for roots by the garbage collector
garbage collector (i.e., typically in a subdirectory of (i.e., typically in a subdirectory of `/nix/var/nix/gcroots/`)
`/nix/var/nix/gcroots/`) *unless* the `--indirect` flag is used. *unless* the `--indirect` flag is used.
If there are multiple results, then multiple symlinks will be If there are multiple results, then multiple symlinks will be
created by sequentially numbering symlinks beyond the first one created by sequentially numbering symlinks beyond the first one
@ -209,8 +208,7 @@ The following suboperations may be specified:
- `--print-roots` - `--print-roots`
This operation prints on standard output the set of roots used by This operation prints on standard output the set of roots used by
the garbage collector. What constitutes a root is described in the garbage collector.
[???](#ssec-gc-roots).
- `--print-live` - `--print-live`
This operation prints on standard output the set of “live” store This operation prints on standard output the set of “live” store

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@ -1,11 +1,12 @@
# Arguments and Variables # Arguments and Variables
The Nix expression in [???](#ex-hello-nix) is a function; it is missing The [Nix expression for GNU Hello](expression-syntax.md) is a
some arguments that have to be filled in somewhere. In the Nix Packages function; it is missing some arguments that have to be filled in
collection this is done in the file `pkgs/top-level/all-packages.nix`, somewhere. In the Nix Packages collection this is done in the file
where all Nix expressions for packages are imported and called with the `pkgs/top-level/all-packages.nix`, where all Nix expressions for
appropriate arguments. Here are some fragments of `all-packages.nix`, packages are imported and called with the appropriate arguments. Here
with annotations of what they mean: are some fragments of `all-packages.nix`, with annotations of what
they mean:
... ...
@ -35,9 +36,10 @@ with annotations of what they mean:
2. Here we *import* the Nix expression for GNU Hello. The import 2. Here we *import* the Nix expression for GNU Hello. The import
operation just loads and returns the specified Nix expression. In operation just loads and returns the specified Nix expression. In
fact, we could just have put the contents of [???](#ex-hello-nix) in fact, we could just have put the contents of the Nix expression
`all-packages.nix` at this point. That would be completely for GNU Hello in `all-packages.nix` at this point. That would be
equivalent, but it would make the file rather bulky. completely equivalent, but it would make `all-packages.nix` rather
bulky.
Note that we refer to `../applications/misc/hello/ex-1`, not Note that we refer to `../applications/misc/hello/ex-1`, not
`../applications/misc/hello/ex-1/default.nix`. When you try to `../applications/misc/hello/ex-1/default.nix`. When you try to
@ -54,7 +56,7 @@ with annotations of what they mean:
The result of this function call is an actual derivation that can be The result of this function call is an actual derivation that can be
built by Nix (since when we fill in the arguments of the function, built by Nix (since when we fill in the arguments of the function,
what we get is its body, which is the call to `stdenv.mkDerivation` what we get is its body, which is the call to `stdenv.mkDerivation`
in [???](#ex-hello-nix)). in the [Nix expression for GNU Hello](expression-syntax.md)).
> **Note** > **Note**
> >

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@ -25,10 +25,10 @@ steps to elucidate what a builder does. It performs the following steps:
So the first step is to set up the environment. This is done by So the first step is to set up the environment. This is done by
calling the `setup` script of the standard environment. The calling the `setup` script of the standard environment. The
environment variable `stdenv` points to the location of the standard environment variable `stdenv` points to the location of the
environment being used. (It wasn't specified explicitly as an standard environment being used. (It wasn't specified explicitly
attribute in [???](#ex-hello-nix), but `mkDerivation` adds it as an attribute in Hello's Nix expression, but `mkDerivation` adds
automatically.) it automatically.)
2. Since Hello needs Perl, we have to make sure that Perl is in the 2. Since Hello needs Perl, we have to make sure that Perl is in the
`PATH`. The `perl` environment variable points to the location of `PATH`. The `perl` environment variable points to the location of

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@ -1,72 +0,0 @@
# Builder Syntax
source $stdenv/setup
PATH=$perl/bin:$PATH
tar xvfz $src
cd hello-*
./configure --prefix=$out
make
make install
[example\_title](#ex-hello-builder) shows the builder referenced from
Hello's Nix expression (stored in
`pkgs/applications/misc/hello/ex-1/builder.sh`). The builder can
actually be made a lot shorter by using the *generic builder* functions
provided by `stdenv`, but here we write out the build steps to elucidate
what a builder does. It performs the following steps:
- When Nix runs a builder, it initially completely clears the
environment (except for the attributes declared in the derivation).
For instance, the `PATH` variable is empty\[1\]. This is done to
prevent undeclared inputs from being used in the build process. If
for example the `PATH` contained `/usr/bin`, then you might
accidentally use `/usr/bin/gcc`.
So the first step is to set up the environment. This is done by
calling the `setup` script of the standard environment. The
environment variable `stdenv` points to the location of the standard
environment being used. (It wasn't specified explicitly as an
attribute in [???](#ex-hello-nix), but `mkDerivation` adds it
automatically.)
- Since Hello needs Perl, we have to make sure that Perl is in the
`PATH`. The `perl` environment variable points to the location of
the Perl package (since it was passed in as an attribute to the
derivation), so `$perl/bin` is the directory containing the Perl
interpreter.
- Now we have to unpack the sources. The `src` attribute was bound to
the result of fetching the Hello source tarball from the network, so
the `src` environment variable points to the location in the Nix
store to which the tarball was downloaded. After unpacking, we `cd`
to the resulting source directory.
The whole build is performed in a temporary directory created in
`/tmp`, by the way. This directory is removed after the builder
finishes, so there is no need to clean up the sources afterwards.
Also, the temporary directory is always newly created, so you don't
have to worry about files from previous builds interfering with the
current build.
- GNU Hello is a typical Autoconf-based package, so we first have to
run its `configure` script. In Nix every package is stored in a
separate location in the Nix store, for instance
`/nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1`. Nix
computes this path by cryptographically hashing all attributes of
the derivation. The path is passed to the builder through the `out`
environment variable. So here we give `configure` the parameter
`--prefix=$out` to cause Hello to be installed in the expected
location.
- Finally we build Hello (`make`) and install it into the location
specified by `out` (`make install`).
If you are wondering about the absence of error checking on the result
of various commands called in the builder: this is because the shell
script is evaluated with Bash's `-e` option, which causes the script to
be aborted if any command fails without an error check.
1. Actually, it's initialised to `/path-not-set` to prevent Bash from
setting it to a default value.

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@ -83,7 +83,7 @@ For instance, `derivation` is also available as `builtins.derivation`.
its elements or attributes are also evaluated recursively. its elements or attributes are also evaluated recursively.
- `derivation` *attrs*; `builtins.derivation` *attrs* - `derivation` *attrs*; `builtins.derivation` *attrs*
`derivation` is described in [???](#ssec-derivation). `derivation` is described in [its own section](derivations.md).
- `dirOf` *s*; `builtins.dirOf` *s* - `dirOf` *s*; `builtins.dirOf` *s*
Return the directory part of the string *s*, that is, everything Return the directory part of the string *s*, that is, everything
@ -233,8 +233,8 @@ For instance, `derivation` is also available as `builtins.derivation`.
> **Note** > **Note**
> >
> Nix will refetch the branch in accordance to > Nix will refetch the branch in accordance with
> [???](#conf-tarball-ttl). > the option `tarball-ttl`.
> **Note** > **Note**
> >
@ -351,19 +351,18 @@ For instance, `derivation` is also available as `builtins.derivation`.
- `import` *path*; `builtins.import` *path* - `import` *path*; `builtins.import` *path*
Load, parse and return the Nix expression in the file *path*. If Load, parse and return the Nix expression in the file *path*. If
*path* is a directory, the file ` default.nix *path* is a directory, the file ` default.nix ` in that directory
` in that directory is loaded. Evaluation aborts if the file is loaded. Evaluation aborts if the file doesnt exist or contains
doesnt exist or contains an incorrect Nix expression. `import` an incorrect Nix expression. `import` implements Nixs module
implements Nixs module system: you can put any Nix expression (such system: you can put any Nix expression (such as a set or a
as a set or a function) in a separate file, and use it from Nix function) in a separate file, and use it from Nix expressions in
expressions in other files. other files.
> **Note** > **Note**
> >
> Unlike some languages, `import` is a regular function in Nix. > Unlike some languages, `import` is a regular function in Nix.
> Paths using the angle bracket syntax (e.g., ` > Paths using the angle bracket syntax (e.g., `import` *\<foo\>*)
> > > > > import` *\<foo\>*) are normal path values (see > are [normal path values](language-values.md).
> [???](#ssec-values)).
A Nix expression loaded by `import` must not contain any *free A Nix expression loaded by `import` must not contain any *free
variables* (identifiers that are not defined in the Nix expression variables* (identifiers that are not defined in the Nix expression
@ -643,11 +642,12 @@ For instance, `derivation` is also available as `builtins.derivation`.
(which is not the case for `abort`). (which is not the case for `abort`).
- `builtins.toFile` *name* *s* - `builtins.toFile` *name* *s*
Store the string *s* in a file in the Nix store and return its path. Store the string *s* in a file in the Nix store and return its
The file has suffix *name*. This file can be used as an input to path. The file has suffix *name*. This file can be used as an
derivations. One application is to write builders “inline”. For input to derivations. One application is to write builders
instance, the following Nix expression combines [???](#ex-hello-nix) “inline”. For instance, the following Nix expression combines the
and [???](#ex-hello-builder) into one file: [Nix expression for GNU Hello](expression-syntax.md) and its
[build script](build-script.md) into one file:
{ stdenv, fetchurl, perl }: { stdenv, fetchurl, perl }:
@ -688,8 +688,9 @@ For instance, `derivation` is also available as `builtins.derivation`.
"; ";
``` ```
Note that `${configFile}` is an antiquotation (see Note that `${configFile}` is an
[???](#ssec-values)), so the result of the expression `configFile` [antiquotation](language-values.md), so the result of the
expression `configFile`
(i.e., a path like `/nix/store/m7p7jfny445k...-foo.conf`) will be (i.e., a path like `/nix/store/m7p7jfny445k...-foo.conf`) will be
spliced into the resulting string. spliced into the resulting string.
@ -786,17 +787,17 @@ For instance, `derivation` is also available as `builtins.derivation`.
container contains a number of servlets (`*.war` files) each container contains a number of servlets (`*.war` files) each
exported under a specific URI prefix. So the servlet configuration exported under a specific URI prefix. So the servlet configuration
is a list of sets containing the `path` and `war` of the servlet is a list of sets containing the `path` and `war` of the servlet
([???](#ex-toxml-co-servlets)). This kind of information is (①). This kind of information is difficult to communicate with the
difficult to communicate with the normal method of passing normal method of passing information through an environment
information through an environment variable, which just concatenates variable, which just concatenates everything together into a
everything together into a string (which might just work in this string (which might just work in this case, but wouldnt work if
case, but wouldnt work if fields are optional or contain lists fields are optional or contain lists themselves). Instead the Nix
themselves). Instead the Nix expression is converted to an XML expression is converted to an XML representation with `toXML`,
representation with `toXML`, which is unambiguous and can easily be which is unambiguous and can easily be processed with the
processed with the appropriate tools. For instance, in the example appropriate tools. For instance, in the example an XSLT stylesheet
an XSLT stylesheet (at point ②) is applied to it (at point ①) to (at point ②) is applied to it (at point ①) to generate the XML
generate the XML configuration file for the Jetty server. The XML configuration file for the Jetty server. The XML representation
representation produced at point ③ by `toXML` is as follows: produced at point ③ by `toXML` is as follows:
<?xml version='1.0' encoding='utf-8'?> <?xml version='1.0' encoding='utf-8'?>
<expr> <expr>
@ -820,10 +821,10 @@ For instance, `derivation` is also available as `builtins.derivation`.
</list> </list>
</expr> </expr>
Note that [???](#ex-toxml) uses the `toFile` built-in to write the Note that we used the `toFile` built-in to write the builder and
builder and the stylesheet “inline” in the Nix expression. The path the stylesheet “inline” in the Nix expression. The path of the
of the stylesheet is spliced into the builder using the syntax stylesheet is spliced into the builder using the syntax `xsltproc
`xsltproc ${stylesheet}`. ${stylesheet}`.
- `builtins.trace` *e1* *e2* - `builtins.trace` *e1* *e2*
Evaluate *e1* and print its abstract syntax representation on Evaluate *e1* and print its abstract syntax representation on

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@ -9,8 +9,9 @@ the attributes of which specify the inputs of the build.
`"x86_64-darwin"`. (To figure out your system type, run `nix -vv `"x86_64-darwin"`. (To figure out your system type, run `nix -vv
--version`.) The build can only be performed on a machine and --version`.) The build can only be performed on a machine and
operating system matching the system type. (Nix can automatically operating system matching the system type. (Nix can automatically
forward builds for other platforms by forwarding them to other [forward builds for other
machines; see [???](#chap-distributed-builds).) platforms](../advanced-topics/distributed-builds.md) by forwarding
them to other machines.)
- There must be an attribute named `name` whose value must be a - There must be an attribute named `name` whose value must be a
string. This is used as a symbolic name for the package by string. This is used as a symbolic name for the package by

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@ -61,9 +61,10 @@ elements (referenced from the figure by number):
sometimes be omitted, in which case `mkDerivation` will fill in a sometimes be omitted, in which case `mkDerivation` will fill in a
default builder (which does a `configure; make; make install`, in default builder (which does a `configure; make; make install`, in
essence). Hello is sufficiently simple that the default builder essence). Hello is sufficiently simple that the default builder
would suffice, but in this case, we will show an actual builder for would suffice, but in this case, we will show an actual builder
educational purposes. The value `./builder.sh` refers to the shell for educational purposes. The value `./builder.sh` refers to the
script shown in [???](#ex-hello-builder), discussed below. shell script shown in the [next section](build-script.md),
discussed below.
5. The builder has to know what the sources of the package are. Here, 5. The builder has to know what the sources of the package are. Here,
the attribute `src` is bound to the result of a call to the the attribute `src` is bound to the result of a call to the

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@ -1,7 +1,7 @@
# Generic Builder Syntax # Generic Builder Syntax
Recall from [???](#ex-hello-builder) that the builder looked something Recall that the [build script for GNU Hello](build-script.md) looked
like this: something like this:
PATH=$perl/bin:$PATH PATH=$perl/bin:$PATH
tar xvfz $src tar xvfz $src
@ -37,11 +37,10 @@ Here is what each line means:
2. The function `genericBuild` is defined in the file `$stdenv/setup`. 2. The function `genericBuild` is defined in the file `$stdenv/setup`.
3. The final step calls the shell function `genericBuild`, which 3. The final step calls the shell function `genericBuild`, which
performs the steps that were done explicitly in performs the steps that were done explicitly in the previous build
[???](#ex-hello-builder). The generic builder is smart enough to script. The generic builder is smart enough to figure out whether
figure out whether to unpack the sources using `gzip`, `bzip2`, etc. to unpack the sources using `gzip`, `bzip2`, etc. It can be
It can be customised in many ways; see the Nixpkgs manual for customised in many ways; see the Nixpkgs manual for details.
details.
Discerning readers will note that the `buildInputs` could just as well Discerning readers will note that the `buildInputs` could just as well
have been set in the Nix expression, like this: have been set in the Nix expression, like this:

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@ -1,8 +1,7 @@
# Operators # Operators
[table\_title](#table-operators) lists the operators in the Nix The table below lists the operators in the Nix expression language, in
expression language, in order of precedence (from strongest to weakest order of precedence (from strongest to weakest binding).
binding).
| Name | Syntax | Associativity | Description | Precedence | | Name | Syntax | Associativity | Description | Precedence |
| ------------------------ | ----------------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- | | ------------------------ | ----------------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- |
@ -28,5 +27,3 @@ binding).
| Logical OR | *e1* `\|\|` *e2* | left | Logical OR. | 13 | | Logical OR | *e1* `\|\|` *e2* | left | Logical OR. | 13 |
| Logical Implication | *e1* `->` *e2* | none | Logical implication (equivalent to `!e1 \|\| | Logical Implication | *e1* `->` *e2* | none | Logical implication (equivalent to `!e1 \|\|
e2`). | 14 | e2`). | 14 |
Operators

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@ -3,7 +3,7 @@
- derivation - derivation
A description of a build action. The result of a derivation is a A description of a build action. The result of a derivation is a
store object. Derivations are typically specified in Nix expressions store object. Derivations are typically specified in Nix expressions
using the [`derivation` primitive](#ssec-derivation). These are using the [`derivation` primitive](expressions/derivations.md). These are
translated into low-level *store derivations* (implicitly by translated into low-level *store derivations* (implicitly by
`nix-env` and `nix-build`, or explicitly by `nix-instantiate`). `nix-env` and `nix-build`, or explicitly by `nix-instantiate`).
@ -53,20 +53,19 @@
paths. paths.
- reachable - reachable
A store path `Q` is reachable from another store path `P` if `Q` is A store path `Q` is reachable from another store path `P` if `Q`
in the [closure](#gloss-closure) of the is in the *closure* of the *references* relation.
[references](#gloss-reference) relation.
- closure - closure
The closure of a store path is the set of store paths that are The closure of a store path is the set of store paths that are
directly or indirectly “reachable” from that store path; that is, directly or indirectly “reachable” from that store path; that is,
its the closure of the path under the its the closure of the path under the *references* relation. For
[references](#gloss-reference) relation. For a package, the closure a package, the closure of its derivation is equivalent to the
of its derivation is equivalent to the build-time dependencies, build-time dependencies, while the closure of its output path is
while the closure of its output path is equivalent to its runtime equivalent to its runtime dependencies. For correct deployment it
dependencies. For correct deployment it is necessary to deploy whole is necessary to deploy whole closures, since otherwise at runtime
closures, since otherwise at runtime files could be missing. The files could be missing. The command `nix-store -qR` prints out
command `nix-store -qR` prints out closures of store paths. closures of store paths.
As an example, if the store object at path `P` contains a reference As an example, if the store object at path `P` contains a reference
to path `Q`, then `Q` is in the closure of `P`. Further, if `Q` to path `Q`, then `Q` is in the closure of `P`. Further, if `Q`
@ -76,7 +75,7 @@
A store path produced by a derivation. A store path produced by a derivation.
- deriver - deriver
The deriver of an [output path](#gloss-output-path) is the store The deriver of an *output path* is the store
derivation that built it. derivation that built it.
- validity - validity
@ -87,16 +86,15 @@
- user environment - user environment
An automatically generated store object that consists of a set of An automatically generated store object that consists of a set of
symlinks to “active” applications, i.e., other store paths. These symlinks to “active” applications, i.e., other store paths. These
are generated automatically by [`nix-env`](#sec-nix-env). See are generated automatically by
[???](#sec-profiles). [`nix-env`](command-ref/nix-env.md). See *profiles*.
- profile - profile
A symlink to the current [user environment](#gloss-user-env) of a A symlink to the current *user environment* of a user, e.g.,
user, e.g., `/nix/var/nix/profiles/default`. `/nix/var/nix/profiles/default`.
- NAR - NAR
A *N*ix *AR*chive. This is a serialisation of a path in the Nix A *N*ix *AR*chive. This is a serialisation of a path in the Nix
store. It can contain regular files, directories and symbolic links. store. It can contain regular files, directories and symbolic
NARs are generated and unpacked using `nix-store --dump` and links. NARs are generated and unpacked using `nix-store --dump`
`nix-store and `nix-store --restore`.
--restore`.

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@ -24,11 +24,11 @@ or completely new ones.)
You can manually download the latest version of Nixpkgs from You can manually download the latest version of Nixpkgs from
<http://nixos.org/nixpkgs/download.html>. However, its much more <http://nixos.org/nixpkgs/download.html>. However, its much more
convenient to use the Nixpkgs *channel*, since it makes it easy to stay convenient to use the Nixpkgs [*channel*](channels.md), since it makes
up to date with new versions of Nixpkgs. (Channels are described in more it easy to stay up to date with new versions of Nixpkgs. Nixpkgs is
detail in [???](#sec-channels).) Nixpkgs is automatically added to your automatically added to your list of “subscribed” channels when you
list of “subscribed” channels when you install Nix. If this is not the install Nix. If this is not the case for some reason, you can add it
case for some reason, you can add it as follows: as follows:
$ nix-channel --add https://nixos.org/channels/nixpkgs-unstable $ nix-channel --add https://nixos.org/channels/nixpkgs-unstable
$ nix-channel --update $ nix-channel --update

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@ -8,7 +8,7 @@ dependencies:
$ nix-copy-closure --to alice@itchy.example.org $(type -p firefox) $ nix-copy-closure --to alice@itchy.example.org $(type -p firefox)
See [???](#sec-nix-copy-closure) for details. See the [manpage for `nix-copy-closure`](../command-ref/nix-copy-closure.md) for details.
With `nix-store With `nix-store
--export` and `nix-store --import` you can write the closure of a store --export` and `nix-store --import` you can write the closure of a store

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@ -1,4 +1,5 @@
This chapter discusses how to do package management with Nix, i.e., how This chapter discusses how to do package management with Nix, i.e.,
to obtain, install, upgrade, and erase packages. This is the “users” how to obtain, install, upgrade, and erase packages. This is the
perspective of the Nix system — people who want to *create* packages “users” perspective of the Nix system — people who want to *create*
should consult [???](#chap-writing-nix-expressions). packages should consult the [chapter on writing Nix
expressions](../expressions/writing-nix-expressions.md).

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@ -104,8 +104,7 @@ These commands switch to the `my-profile` and default profile,
respectively. If the profile doesnt exist, it will be created respectively. If the profile doesnt exist, it will be created
automatically. You should be careful about storing a profile in another automatically. You should be careful about storing a profile in another
location than the `profiles` directory, since otherwise it might not be location than the `profiles` directory, since otherwise it might not be
used as a root of the garbage collector (see used as a root of the [garbage collector](garbage-collection.md).
[???](#sec-garbage-collection)).
All `nix-env` operations work on the profile pointed to by All `nix-env` operations work on the profile pointed to by
`~/.nix-profile`, but you can override this using the `--profile` option `~/.nix-profile`, but you can override this using the `--profile` option