<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xi="http://www.w3.org/2001/XInclude" xml:id="sec-nix-copy-closure"> <refmeta> <refentrytitle>nix-copy-closure</refentrytitle> <manvolnum>1</manvolnum> <refmiscinfo class="source">Nix</refmiscinfo> <refmiscinfo class="version"><xi:include href="version.txt" parse="text"/></refmiscinfo> </refmeta> <refnamediv> <refname>nix-copy-closure</refname> <refpurpose>copy a closure to or from a remote machine via SSH</refpurpose> </refnamediv> <refsynopsisdiv> <cmdsynopsis> <command>nix-copy-closure</command> <group> <arg choice='plain'><option>--to</option></arg> <arg choice='plain'><option>--from</option></arg> </group> <arg><option>--sign</option></arg> <arg><option>--gzip</option></arg> <arg choice='plain'> <arg><replaceable>user@</replaceable></arg><replaceable>machine</replaceable> </arg> <arg choice='plain'><replaceable>paths</replaceable></arg> </cmdsynopsis> </refsynopsisdiv> <refsection><title>Description</title> <para><command>nix-copy-closure</command> gives you an easy and efficient way to exchange software between machines. Given one or more Nix store paths <replaceable>paths</replaceable> on the local machine, <command>nix-copy-closure</command> computes the closure of those paths (i.e. all their dependencies in the Nix store), and copies all paths in the closure to the remote machine via the <command>ssh</command> (Secure Shell) command. With the <option>--from</option>, the direction is reversed: the closure of <replaceable>paths</replaceable> on a remote machine is copied to the Nix store on the local machine.</para> <para>This command is efficient because it only sends the store paths that are missing on the target machine.</para> <para>Since <command>nix-copy-closure</command> calls <command>ssh</command>, you may be asked to type in the appropriate password or passphrase. In fact, you may be asked <emphasis>twice</emphasis> because <command>nix-copy-closure</command> currently connects twice to the remote machine, first to get the set of paths missing on the target machine, and second to send the dump of those paths. If this bothers you, use <command>ssh-agent</command>.</para> <refsection><title>Options</title> <variablelist> <varlistentry><term><option>--to</option></term> <listitem><para>Copy the closure of <replaceable>paths</replaceable> from the local Nix store to the Nix store on <replaceable>machine</replaceable>. This is the default.</para></listitem> </varlistentry> <varlistentry><term><option>--from</option></term> <listitem><para>Copy the closure of <replaceable>paths</replaceable> from the Nix store on <replaceable>machine</replaceable> to the local Nix store.</para></listitem> </varlistentry> <varlistentry><term><option>--sign</option></term> <listitem><para>Let the sending machine cryptographically sign the dump of each path with the key in <filename>/nix/etc/nix/signing-key.sec</filename>. If the user on the target machine does not have direct access to the Nix store (i.e., if the target machine has a multi-user Nix installation), then the target machine will check the dump against <filename>/nix/etc/nix/signing-key.pub</filename> before unpacking it in its Nix store. This allows secure sharing of store paths between untrusted users on two machines, provided that there is a trust relation between the Nix installations on both machines (namely, they have matching public/secret keys).</para></listitem> </varlistentry> <varlistentry><term><option>--gzip</option></term> <listitem><para>Compress the dump of each path with <command>gzip</command> before sending it.</para></listitem> </varlistentry> </variablelist> </refsection> <refsection><title>Environment variables</title> <variablelist> <varlistentry><term><envar>NIX_SSHOPTS</envar></term> <listitem><para>Additional options to be passed to <command>ssh</command> on the command line.</para></listitem> </varlistentry> </variablelist> </refsection> <refsection><title>Examples</title> <para>Copy Firefox with all its dependencies to a remote machine: <screen> $ nix-copy-closure --to alice@itchy.labs $(type -tP firefox)</screen> </para> <para>Copy Subversion from a remote machine and then install it into a user environment: <screen> $ nix-copy-closure --from alice@itchy.labs \ /nix/store/0dj0503hjxy5mbwlafv1rsbdiyx1gkdy-subversion-1.4.4 $ nix-env -i /nix/store/0dj0503hjxy5mbwlafv1rsbdiyx1gkdy-subversion-1.4.4 </screen> </para> </refsection> </refsection> </refentry>