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								<chapter xmlns="http://docbook.org/ns/docbook"
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								         xmlns:xlink="http://www.w3.org/1999/xlink"
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								         xmlns:xi="http://www.w3.org/2001/XInclude"
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								         version="5.0"
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								         xml:id="sec-user-management">
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								<title>User Management</title>
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								<para>NixOS supports both declarative and imperative styles of user
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								management.  In the declarative style, users are specified in
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								<filename>configuration.nix</filename>.  For instance, the following
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								states that a user account named <literal>alice</literal> shall exist:
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								<programlisting>
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								users.extraUsers.alice =
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								  { isNormalUser = true;
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								    home = "/home/alice";
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								    description = "Alice Foobar";
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								    extraGroups = [ "wheel" "networkmanager" ];
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								    openssh.authorizedKeys.keys = [ "ssh-dss AAAAB3Nza... alice@foobar" ];
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								  };
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								</programlisting>
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								Note that <literal>alice</literal> is a member of the
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								<literal>wheel</literal> and <literal>networkmanager</literal> groups,
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								which allows her to use <command>sudo</command> to execute commands as
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								<literal>root</literal> and to configure the network, respectively.
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								Also note the SSH public key that allows remote logins with the
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								corresponding private key. Users created in this way do not have a
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								password by default, so they cannot log in via mechanisms that require
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								a password. However, you can use the <command>passwd</command> program
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								to set a password, which is retained across invocations of
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								<command>nixos-rebuild</command>.</para>
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								<para>If you set users.mutableUsers to false, then the contents of /etc/passwd
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								and /etc/group will be congruent to your NixOS configuration. For instance,
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								if you remove a user from users.extraUsers and run nixos-rebuild, the user
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								account will cease to exist. Also, imperative commands for managing users
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								and groups, such as useradd, are no longer available.</para>
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								<para>A user ID (uid) is assigned automatically.  You can also specify
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								a uid manually by adding
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								<programlisting>
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								    uid = 1000;
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								</programlisting>
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								to the user specification.</para>
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								<para>Groups can be specified similarly.  The following states that a
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								group named <literal>students</literal> shall exist:
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								<programlisting>
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								users.extraGroups.students.gid = 1000;
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								</programlisting>
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								As with users, the group ID (gid) is optional and will be assigned
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								automatically if it’s missing.</para>
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								<para>In the imperative style, users and groups are managed by
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								commands such as <command>useradd</command>,
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								<command>groupmod</command> and so on.  For instance, to create a user
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								account named <literal>alice</literal>:
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								<screen>
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								$ useradd -m alice</screen>
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								The flag <option>-m</option> causes the creation of a home directory
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								for the new user, which is generally what you want.  The user does not
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								have an initial password and therefore cannot log in.  A password can
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								be set using the <command>passwd</command> utility:
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								<screen>
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								$ passwd alice
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								Enter new UNIX password: ***
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								Retype new UNIX password: ***
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								</screen>
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								A user can be deleted using <command>userdel</command>:
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								<screen>
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								$ userdel -r alice</screen>
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								The flag <option>-r</option> deletes the user’s home directory.
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								Accounts can be modified using <command>usermod</command>.  Unix
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								groups can be managed using <command>groupadd</command>,
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								<command>groupmod</command> and <command>groupdel</command>.</para>
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								</chapter>
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