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| -rw-r--r-- | doc/manual/installation.xml | 61 |
1 files changed, 12 insertions, 49 deletions
diff --git a/doc/manual/installation.xml b/doc/manual/installation.xml index a7140910604f..423bef5e22a8 100644 --- a/doc/manual/installation.xml +++ b/doc/manual/installation.xml @@ -308,7 +308,7 @@ a Trojan horse.</para> <section><title>Single-user mode</title> - + <para>In single-user mode, all Nix operations that access the database in <filename><replaceable>prefix</replaceable>/var/nix/db</filename> or modify the Nix store in @@ -354,58 +354,21 @@ done by <systemitem class="username">root</systemitem>.</para></note> <para>The <emphasis>build users</emphasis> are the special UIDs under which builds are performed. They should all be members of the -<emphasis>build users group</emphasis> (usually called -<literal>nixbld</literal>). This group should have no other members. -The build users should not be members of any other group.</para> - -<para>Here is a typical <filename>/etc/group</filename> definition of -the build users group with 10 build users: - -<programlisting> -nixbld:!:30000:nixbld1,nixbld2,nixbld3,nixbld4,nixbld5,nixbld6,nixbld7,nixbld8,nixbld9,nixbld10 -</programlisting> - -In this example the <literal>nixbld</literal> group has UID 30000, but -of course it can be anything that doesn’t collide with an existing -group.</para> - -<para>Here is the corresponding part of -<filename>/etc/passwd</filename>: - -<programlisting> -nixbld1:x:30001:65534:Nix build user 1:/var/empty:/noshell -nixbld2:x:30002:65534:Nix build user 2:/var/empty:/noshell -nixbld3:x:30003:65534:Nix build user 3:/var/empty:/noshell -... -nixbld10:x:30010:65534:Nix build user 10:/var/empty:/noshell -</programlisting> - -The home directory of the build users should not exist or should be an -empty directory to which they do not have write access.</para> - -<para>The build users should have write access to the Nix store, but -they should not have the right to delete files. Thus the Nix store’s -group should be the build users group, and it should have the sticky -bit turned on (like <filename>/tmp</filename>): +<emphasis>build users group</emphasis> <literal>nixbld</literal>. +This group should have no other members. The build users should not +be members of any other group. On Linux, you can create the group and +users as follows: <screen> -$ chown root.nixbld /nix/store -$ chmod 1775 /nix/store +$ groupadd -r nixbld +$ for n in $(seq 1 10); do useradd -c "Nix build user $n" \ + -d /var/empty -g nixbld -G nixbld -M -N -r -s "$(which nologin)" \ + nixbld$n; done </screen> -</para> - -<para>Finally, you should tell Nix to use the build users by -specifying the build users group in the <link -linkend="conf-build-users-group"><literal>build-users-group</literal> -option</link> in the <link linkend="sec-conf-file">Nix configuration -file</link> (usually <literal>/etc/nix/nix.conf</literal>): - -<programlisting> -build-users-group = nixbld -</programlisting> - -</para> +This creates 10 build users. There can never be more concurrent builds +than the number of build users, so you may want to increase this if +you expect to do many builds at the same time.</para> </section> |