diff options
| -rw-r--r-- | doc/manual/nix-store.xml | 76 | ||||
| -rw-r--r-- | src/nix-store/main.cc | 2 |
2 files changed, 75 insertions, 3 deletions
diff --git a/doc/manual/nix-store.xml b/doc/manual/nix-store.xml index 41257e3de..95d0b03d4 100644 --- a/doc/manual/nix-store.xml +++ b/doc/manual/nix-store.xml @@ -278,7 +278,7 @@ $ nix-store --gc</screen> <!--######################################################################--> -<refsection><title>Operation <option>--query</option></title> +<refsection xml:id='refsec-nix-store-query'><title>Operation <option>--query</option></title> <refsection><title>Synopsis</title> @@ -674,7 +674,79 @@ in Nix itself.</para> </refsection> -<!-- TODO: dump / restore --> +<!--######################################################################--> + +<refsection><title>Operation <option>--dump</option></title> + +<refsection> + <title>Synopsis</title> + <cmdsynopsis> + <command>nix-store</command> + <arg choice='plain'><option>--dump</option></arg> + <arg choice='plain'><replaceable>path</replaceable></arg> + </cmdsynopsis> +</refsection> + +<refsection><title>Description</title> + +<para>The operation <option>--dump</option> produces a NAR (Nix +ARchive) file containing the contents of the file system tree rooted +at <replaceable>path</replaceable>. The archive is written to +standard output.</para> + +<para>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 +644 or 755 permission.</para> + +<para>Also, a NAR archive is <emphasis>canonical</emphasis>, meaning +that “equal” paths always produce the same NAR archive. For instance, +directory entries are always sorted so that the actual on-disk order +doesn’t 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 Nix’s database +(see <link linkend="refsec-nix-store-query"><literal>nix-store -q +--hash</literal></link>) are SHA-256 hashes of the NAR dump of each +store path.</para> + +<para>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).</para> + +<para>A Nix archive can be unpacked using <literal>nix-store +--restore</literal>.</para> + +</refsection> + + +</refsection> + + +<!--######################################################################--> + +<refsection><title>Operation <option>--restore</option></title> + +<refsection> + <title>Synopsis</title> + <cmdsynopsis> + <command>nix-store</command> + <arg choice='plain'><option>--restore</option></arg> + <arg choice='plain'><replaceable>path</replaceable></arg> + </cmdsynopsis> +</refsection> + +<refsection><title>Description</title> + +<para>The operation <option>--restore</option> unpacks a NAR archive +to <replaceable>path</replaceable>, which must not already exist. The +archive is read from standard input.</para> + +</refsection> + + +</refsection> </refentry> diff --git a/src/nix-store/main.cc b/src/nix-store/main.cc index 42c3074ff..b83eb8837 100644 --- a/src/nix-store/main.cc +++ b/src/nix-store/main.cc @@ -599,7 +599,7 @@ struct StdinSource : RestoreSource }; -/* Restore a value from a Nix archive. The archive is written to +/* Restore a value from a Nix archive. The archive is read from standard input. */ static void opRestore(Strings opFlags, Strings opArgs) { |