Nix Cookbook: Difference between revisions

mNo edit summary
one-liner to bulk download
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With this warning, consumers will have time to patch their codes.
With this warning, consumers will have time to patch their codes.
== Bulk pre-download all dependencies of a package ==
Sometimes we need to download all source dependencies of a package.
E.G. a long build is being planned, so we first download all needed files, so that after that we only need to worry about local (non-Internet) issues.
Here is a one-liner for downloading all the source dependencies of a package (thanks Eelco Dolstra!):
<syntaxHighlight lang="shell">
$> nix-store -r $(grep -l outputHash $(nix-store -qR $(nix-instantiate '<nixpkgs>' -A bochs) | grep '.drv$'))
</syntaxHighlight>
Let's dissect this:
<syntaxHighlight lang="sh">
## instantiate bochs into `.drv` files and print the filenames;
instantiate=$(nix-instantiate '<nixpkgs>' -A bochs)
## print all references/requirements, filtering the .drv files (which is where static derivations live)
requirements=$(nix-store -qR $intantiate | grep '.drv$')
## keep only the source derivations, since those will have a predefined hash of the output
sources=$(grep -l outputHash $requirements)
## realize those derivations, downloading all sources and storing them in the nix store
nix-store -r $sources
</syntaxHighlight>
After that, all sources will be locally stored!


== Wrapping packages ==
== Wrapping packages ==