<section xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="ssec-copy-closure">

<title>Copying Closures Via SSH</title>

<para>The command <command
linkend="sec-nix-copy-closure">nix-copy-closure</command> copies a Nix
store path along with all its dependencies to or from another machine
via the SSH protocol.  It doesn’t copy store paths that are already
present on the target machine.  For example, the following command
copies Firefox with all its dependencies:

<screen>
$ nix-copy-closure --to alice@itchy.example.org $(type -p firefox)</screen>

See <xref linkend='sec-nix-copy-closure' /> for details.</para>

<para>With <command linkend='refsec-nix-store-export'>nix-store
--export</command> and <command
linkend='refsec-nix-store-import'>nix-store --import</command> you can
write the closure of a store path (that is, the path and all its
dependencies) to a file, and then unpack that file into another Nix
store.  For example,

<screen>
$ nix-store --export $(nix-store -qR $(type -p firefox)) > firefox.closure</screen>

writes the closure of Firefox to a file.  You can then copy this file
to another machine and install the closure:

<screen>
$ nix-store --import &lt; firefox.closure</screen>

Any store paths in the closure that are already present in the target
store are ignored.  It is also possible to pipe the export into
another command, e.g. to copy and install a closure directly to/on
another machine:

<screen>
$ nix-store --export $(nix-store -qR $(type -p firefox)) | bzip2 | \
    ssh alice@itchy.example.org "bunzip2 | nix-store --import"</screen>

However, <command>nix-copy-closure</command> is generally more
efficient because it only copies paths that are not already present in
the target Nix store.</para>

</section>
