2023-03-23 17:27:41 +02:00
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# Name
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`nix-store --dump` - write a single path to a Nix Archive
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## Synopsis
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`nix-store` `--dump` *path*
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## Description
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The operation `--dump` produces a NAR (Nix ARchive) file containing the
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contents of the file system tree rooted at *path*. The archive is
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written to standard output.
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A NAR archive is like a TAR or Zip archive, but it contains only the
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information that Nix considers important. For instance, timestamps are
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elided because all files in the Nix store have their timestamp set to 0
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anyway. Likewise, all permissions are left out except for the execute
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bit, because all files in the Nix store have 444 or 555 permission.
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Also, a NAR archive is *canonical*, meaning that “equal” paths always
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produce the same NAR archive. For instance, directory entries are
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always sorted so that the actual on-disk order doesn’t influence the
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result. This means that the cryptographic hash of a NAR dump of a
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path is usable as a fingerprint of the contents of the path. Indeed,
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2023-04-30 16:52:38 +03:00
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the hashes of store paths stored in Nix’s database (see `nix-store --query
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2023-03-23 17:27:41 +02:00
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--hash`) are SHA-256 hashes of the NAR dump of each store path.
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NAR archives support filenames of unlimited length and 64-bit file
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sizes. They can contain regular files, directories, and symbolic links,
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but not other types of files (such as device nodes).
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A Nix archive can be unpacked using `nix-store
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--restore`.
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{{#include ./opt-common.md}}
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{{#include ../opt-common.md}}
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{{#include ../env-common.md}}
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