nix-super/doc/manual/src/command-ref/nix-store/dump.md
Alexander Schmolck 8d4b6766e2 Convert short nix options to long ones
e.g. nix-env -e subversion => nix-env --uninstall subversion

The aim is to make the documentation less cryptic for newcomers and the
long options are more self-documenting.

The change was made with the following script:

<https://github.com/aschmolck/convert-short-nix-opts-to-long-ones>

and sanity checked visually.
2023-05-17 08:10:30 +01:00

1.4 KiB
Raw Blame History

Name

nix-store --dump - write a single path to a Nix Archive

Synopsis

nix-store --dump path

Description

The operation --dump produces a NAR (Nix ARchive) file containing the contents of the file system tree rooted at path. The archive is written to standard output.

A NAR archive is like a TAR or Zip archive, but it contains only the information that Nix considers important. For instance, timestamps are elided because all files in the Nix store have their timestamp set to 0 anyway. Likewise, all permissions are left out except for the execute bit, because all files in the Nix store have 444 or 555 permission.

Also, a NAR archive is canonical, meaning that “equal” paths always produce the same NAR archive. For instance, directory entries are always sorted so that the actual on-disk order doesnt influence the result. This means that the cryptographic hash of a NAR dump of a path is usable as a fingerprint of the contents of the path. Indeed, the hashes of store paths stored in Nixs database (see nix-store --query --hash) are SHA-256 hashes of the NAR dump of each store path.

NAR archives support filenames of unlimited length and 64-bit file sizes. They can contain regular files, directories, and symbolic links, but not other types of files (such as device nodes).

A Nix archive can be unpacked using nix-store --restore.

{{#include ./opt-common.md}}

{{#include ../opt-common.md}}

{{#include ../env-common.md}}