.\" -*- mode: troff; coding: utf-8 -*-
.TH "nix3-show-derivation" "1" ""
.PP
\fBWarning\fR: This program is \fBexperimental\fR and its interface is subject to change.
.SH Name
\fCnix show-derivation\fR - show the contents of a store derivation
.SH Synopsis
\fCnix show-derivation\fR [\fIoption\fR\[u2026]] \fIinstallables\fR\[u2026]
.SH Examples
.IP "\(bu" 2
Show the store derivation that results from evaluating the Hello
package:
.LP
.EX
# nix show-derivation nixpkgs#hello
{
\(dq/nix/store/s6rn4jz1sin56rf4qj5b5v8jxjm32hlk-hello-2.10.drv\(dq: {
  …
}
}
.EE
.IP "\(bu" 2
Show the full derivation graph (if available) that produced your
NixOS system:
.LP
.EX
# nix show-derivation -r /run/current-system
.EE
.IP "\(bu" 2
Print all files fetched using \fCfetchurl\fR by Firefox\[u2019]s dependency
graph:
.LP
.EX
# nix show-derivation -r nixpkgs#firefox \e
| jq -r '.[] | select(.outputs.out.hash and .env.urls) | .env.urls' \e
| uniq | sort
.EE
.IP
Note that \fC.outputs.out.hash\fR selects \fIfixed-output derivations\fR
(derivations that produce output with a specified content hash),
while \fC.env.urls\fR selects derivations with a \fCurls\fR attribute.
.SH Description
This command prints on standard output a JSON representation of the
store derivations to which \fIinstallables\fR evaluate. Store derivations
are used internally by Nix. They are store paths with extension \fC.drv\fR
that represent the build-time dependency graph to which a Nix
expression evaluates.
.PP
By default, this command only shows top-level derivations, but with
\fC--recursive\fR, it also shows their dependencies.
.PP
The JSON output is a JSON object whose keys are the store paths of the
derivations, and whose values are a JSON object with the following
fields:
.IP "\(bu" 2
\fCoutputs\fR: Information about the output paths of the
derivation. This is a JSON object with one member per output, where
the key is the output name and the value is a JSON object with these
fields:
.RS
.IP "\(bu" 2
\fCpath\fR: The output path.
.if n \
.sp -1
.if t \
.sp -0.25v
.IP "\(bu" 2
\fChashAlgo\fR: For fixed-output derivations, the hashing algorithm
(e.g. \fCsha256\fR), optionally prefixed by \fCr:\fR if \fChash\fR denotes a
NAR hash rather than a flat file hash.
.if n \
.sp -1
.if t \
.sp -0.25v
.IP "\(bu" 2
\fChash\fR: For fixed-output derivations, the expected content hash in
base-16.
.RE
.IP
Example:
.LP
.EX
\(dqoutputs\(dq: {
\(dqout\(dq: {
  \(dqpath\(dq: \(dq/nix/store/2543j7c6jn75blc3drf4g5vhb1rhdq29-source\(dq,
  \(dqhashAlgo\(dq: \(dqr:sha256\(dq,
  \(dqhash\(dq: \(dq6fc80dcc62179dbc12fc0b5881275898f93444833d21b89dfe5f7fbcbb1d0d62\(dq
}
}
.EE
.IP "\(bu" 2
\fCinputSrcs\fR: A list of store paths on which this derivation depends.
.IP "\(bu" 2
\fCinputDrvs\fR: A JSON object specifying the derivations on which this
derivation depends, and what outputs of those derivations. For
example,
.LP
.EX
\(dqinputDrvs\(dq: {
\(dq/nix/store/6lkh5yi7nlb7l6dr8fljlli5zfd9hq58-curl-7.73.0.drv\(dq: [\(dqdev\(dq],
\(dq/nix/store/fn3kgnfzl5dzym26j8g907gq3kbm8bfh-unzip-6.0.drv\(dq: [\(dqout\(dq]
}
.EE
.IP
specifies that this derivation depends on the \fCdev\fR output of
\fCcurl\fR, and the \fCout\fR output of \fCunzip\fR.
.IP "\(bu" 2
\fCsystem\fR: The system type on which this derivation is to be built
(e.g. \fCx86_64-linux\fR).
.IP "\(bu" 2
\fCbuilder\fR: The absolute path of the program to be executed to run
the build. Typically this is the \fCbash\fR shell
(e.g. \fC/nix/store/r3j288vpmczbl500w6zz89gyfa4nr0b1-bash-4.4-p23/bin/bash\fR).
.IP "\(bu" 2
\fCargs\fR: The command-line arguments passed to the \fCbuilder\fR.
.IP "\(bu" 2
\fCenv\fR: The environment passed to the \fCbuilder\fR.
.SH Options
.IP "\(bu" 2
\fC--recursive\fR / \fC-r\fR
.br
Include the dependencies of the specified derivations.
.LP
\fBCommon evaluation options:\fR
.IP "\(bu" 2
\fC--arg\fR \fIname\fR \fIexpr\fR
.br
Pass the value \fIexpr\fR as the argument \fIname\fR to Nix functions.
.IP "\(bu" 2
\fC--argstr\fR \fIname\fR \fIstring\fR
.br
Pass the string \fIstring\fR as the argument \fIname\fR to Nix functions.
.IP "\(bu" 2
\fC--eval-store\fR \fIstore-url\fR
.br
The Nix store to use for evaluations.
.IP "\(bu" 2
\fC--impure\fR
.br
Allow access to mutable paths and repositories.
.IP "\(bu" 2
\fC--include\fR / \fC-I\fR \fIpath\fR
.br
Add \fIpath\fR to the list of locations used to look up \fC<...>\fR file names.
.IP "\(bu" 2
\fC--override-flake\fR \fIoriginal-ref\fR \fIresolved-ref\fR
.br
Override the flake registries, redirecting \fIoriginal-ref\fR to \fIresolved-ref\fR.
.LP
\fBCommon flake-related options:\fR
.IP "\(bu" 2
\fC--commit-lock-file\fR
.br
Commit changes to the flake\[u2019]s lock file.
.IP "\(bu" 2
\fC--inputs-from\fR \fIflake-url\fR
.br
Use the inputs of the specified flake as registry entries.
.IP "\(bu" 2
\fC--no-registries\fR
.br
Don\[u2019]t allow lookups in the flake registries. This option is deprecated; use \fC--no-use-registries\fR.
.IP "\(bu" 2
\fC--no-update-lock-file\fR
.br
Do not allow any updates to the flake\[u2019]s lock file.
.IP "\(bu" 2
\fC--no-write-lock-file\fR
.br
Do not write the flake\[u2019]s newly generated lock file.
.IP "\(bu" 2
\fC--override-input\fR \fIinput-path\fR \fIflake-url\fR
.br
Override a specific flake input (e.g. \fCdwarffs/nixpkgs\fR). This implies \fC--no-write-lock-file\fR.
.IP "\(bu" 2
\fC--recreate-lock-file\fR
.br
Recreate the flake\[u2019]s lock file from scratch.
.IP "\(bu" 2
\fC--update-input\fR \fIinput-path\fR
.br
Update a specific flake input (ignoring its previous entry in the lock file).
.LP
\fBOptions that change the interpretation of installables:\fR
.IP "\(bu" 2
\fC--derivation\fR
.br
Operate on the store derivation rather than its outputs.
.IP "\(bu" 2
\fC--expr\fR \fIexpr\fR
.br
Interpret installables as attribute paths relative to the Nix expression \fIexpr\fR.
.IP "\(bu" 2
\fC--file\fR / \fC-f\fR \fIfile\fR
.br
Interpret installables as attribute paths relative to the Nix expression stored in \fIfile\fR. If \fIfile\fR is the character -, then a Nix expression will be read from standard input.