Nix command: Difference between revisions

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This article is about all nix subcommands. Its written for nix 2.4 or newer.
This article is about the new <code>nix</code> command and all of its subcommands. The new <code>nix</code> command is intended to unify many different Nix package manager utilities that exist currently as many separate commands, eg. <code>nix-build</code>, <code>nix-shell</code>, etc.  
Older nix versions might have different commands.
 
See the [https://nixos.org/manual/nix/stable/command-ref/experimental-commands.html Nix manual] for a complete reference.


== Enabling the nix command ==
== Enabling the nix command ==


In nix 2.4 the nix command must be enabled explicitly set <code>experimental-features = nix-command</code>
In nix 2.4 the nix command must be enabled explicitly set. You can do this in a few different ways.
in <code>~/.config/nix/nix.conf</code> or system-wide in <code>/etc/nix/nix.conf</code>.
 
In NixOS the latter one can be also achieved by using:
For an individual invocation, eg.
<syntaxHighlight lang=text>
nix --experimental-features nix-command build ...
</syntaxHighlight>
 
Or by setting a user-specific configuration,
<syntaxHighlight lang=toml>
# ~/.config/nix/nix.conf
experimental-features = nix-command
</syntaxHighlight>
in <code>~/.config/nix/nix.conf</code>.


On NixOS you can't edit <code>/etc/nix/nix.conf</code> directly, but you can enable this feature by editing <code>/etc/nixos/configuration.nix</code>:
<syntaxHighlight lang=nix>
<syntaxHighlight lang=nix>
#
{ pkgs, ... }: {
{ pkgs, ... }: {
  nix.extraOptions = ''
  …
      experimental-features = nix-command
  nix.settings.experimental-features = [ "nix-command" ];
  '';
  …
}
}
</syntaxHighlight>
</syntaxHighlight>
and then run <code>sudo nixos-rebuild switch</code> as always.


In the following we describe all sub commands of nix:
== Switching between <code>nix-env</code> and <code>nix profile</code> ==


== Main commands ==
{{warning|Be careful when testing.
Once you have used <code>nix profile</code> you can no longer use <code>nix-env</code> without first deleting <code>/nix/var/nix/profiles/per-user/$USER/profile</code>}}


=== <code>nix build</code> ===
Once you installed a package with <code>nix profile</code>, you
get the following error message when using <code>nix-env</code>:
build a derivation or fetch a store path


<syntaxHighlight lang=console>
$ nix-env -f '<nixpkgs>' -iA 'hello'
error: --- Error ----------------------------------------------------------------------------------------------------------------- nix-env
profile '/nix/var/nix/profiles/per-user/joerg/profile' is incompatible with 'nix-env'; please use 'nix profile' instead
</syntaxHighlight>


===  <code>nix develop</code> ===
To migrate back to <code>nix-env</code> you can delete your current profile:


run a bash shell that provides the build environment of a derivation
{{warning|This will delete packages that have been installed before, so you may want to back this information before running the command.}}


<syntaxHighlight lang=console>
$ rm -rf /nix/var/nix/profiles/per-user/$USER/profile
</syntaxHighlight>


=== <code>nix flake</code> ===
== New equivalents to old commands ==
 
<syntaxHighlight lang=console>
manage Nix flakes
# create a store derivation for a package defined in the current directory's default.nix
 
old$ nix-instantiate -A somepackage
 
# assumes you are now using flakes
=== <code>nix profile</code> ===
new$ nix eval .#somepackage.drvPath
 
# alternative option
manage Nix profiles
new$ nix derivation show .#somepackage | jq '.[keys[0]]' | nix derivation add
 
</syntaxHighlight>
=== <code>nix repl</code> ===
 
start an interactive environment for evaluating Nix expressions
 
=== <code>nix run</code> ===
 
run a Nix application
 
=== <code>nix search</code ===
 
query available packages
 
=== <code>nix shell</code> ===
 
run a shell in which the specified packages are available
 
== Infrequently used commands ==
 
=== <code>nix copy</code> ===
copy paths between Nix stores
 
=== <code>nix edit</code> ===
 
open the Nix expression of a Nix package in $EDITOR
 
=== <code>nix eval</code> ===
 
evaluate a Nix expression
 
=== <code>nix log</code> ===
 
show the build log of the specified packages or paths, if available
 
=== <code>nix path-info</code> ===
 
query information about store paths
 
=== <code>nix registry</code> ===
 
manage the flake registry
 
=== <code>nix verify</code> ===
 
verify the integrity of store paths
 
=== <code>nix why-depends</code> ===
 
show why a package has another package in its closure
 
== Utility/scripting commands ==
 
=== <code>nix add-to-store</code> ===
 
add a path to the Nix store
 
=== <code>nix cat-nar</code> ===
 
print the contents of a file inside a NAR file on stdout
 
=== <code>nix cat-store</code> ===
 
print the contents of a file in the Nix store on stdout
 
=== <code>nix copy-sigs</code> ===
 
copy path signatures from substituters (like binary caches)
 
=== <code>nix dump-path</code> ===
 
dump a store path to stdout (in NAR format)
 
=== <code>nix hash-file</code> ===
 
print cryptographic hash of the NAR serialisation of a path
 
=== <code>nix hash-path</code> ===
 
print cryptographic hash of the NAR serialisation of a path
 
=== <code>ls-nar</code> ===
 
show information about a path inside a NAR file
 
=== <code>nix ls-store</code> ===
 
show information about a path in the Nix store
 
=== <code>nix make-content-addressable</code> ===
 
rewrite a path or closure to content-addressable form
 
=== <code>nix optimise-store</code> ===
 
replace identical files in the store by hard links
 
=== <code>nix ping-store</code> ===
 
test whether a store can be opened
 
=== <code>nix print-dev-env</code> ===
 
print shell code that can be sourced by bash to reproduce the build environment of a derivation
 
=== <code>nix show-config</code> ===
 
show the Nix configuration
 
=== <code>nix show-derivation</code> ===
 
show the contents of a store derivation
 
=== <code>nix sign-paths</code> ===
 
sign the specified paths
 
=== <code>nix to-base16</code> ===
 
convert a hash to base-16 representation
 
=== <code>nix to-base32</code> ===
 
convert a hash to base-32 representation
 
=== <code>nix to-base64</code> ===
 
convert a hash to base-64 representation
 
=== <code>nix to-sri</code> ===


convert a hash to SRI representation
[[Category:Nix]]

Latest revision as of 18:06, 1 April 2024

This article is about the new nix command and all of its subcommands. The new nix command is intended to unify many different Nix package manager utilities that exist currently as many separate commands, eg. nix-build, nix-shell, etc.

See the Nix manual for a complete reference.

Enabling the nix command

In nix 2.4 the nix command must be enabled explicitly set. You can do this in a few different ways.

For an individual invocation, eg. 

nix --experimental-features nix-command build ...

Or by setting a user-specific configuration, 

# ~/.config/nix/nix.conf
experimental-features = nix-command

in ~/.config/nix/nix.conf.

On NixOS you can't edit /etc/nix/nix.conf directly, but you can enable this feature by editing /etc/nixos/configuration.nix: 

# 
{ pkgs, ... }: {
  …
  nix.settings.experimental-features = [ "nix-command" ];
  …
}

and then run sudo nixos-rebuild switch as always.

Switching between nix-env and nix profile

Warning: Be careful when testing. Once you have used nix profile you can no longer use nix-env without first deleting /nix/var/nix/profiles/per-user/$USER/profile

Once you installed a package with nix profile, you get the following error message when using nix-env: 

$ nix-env -f '<nixpkgs>' -iA 'hello'
error: --- Error ----------------------------------------------------------------------------------------------------------------- nix-env
profile '/nix/var/nix/profiles/per-user/joerg/profile' is incompatible with 'nix-env'; please use 'nix profile' instead

To migrate back to nix-env you can delete your current profile:

Warning: This will delete packages that have been installed before, so you may want to back this information before running the command.
$ rm -rf /nix/var/nix/profiles/per-user/$USER/profile

New equivalents to old commands

# create a store derivation for a package defined in the current directory's default.nix
old$ nix-instantiate -A somepackage
# assumes you are now using flakes
new$ nix eval .#somepackage.drvPath
# alternative option
new$ nix derivation show .#somepackage | jq '.[keys[0]]' | nix derivation add
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