Merge pull request #17203 from poettering/resolv-conf-mode

[thirdparty/systemd.git] / man / homectl.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->

<refentry id="homectl" conditional='ENABLE_HOMED'
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>homectl</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>homectl</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>homectl</refname>
    <refpurpose>Create, remove, change or inspect home directories</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>homectl</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="req">COMMAND</arg>
      <arg choice="opt" rep="repeat">NAME</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>homectl</command> may be used to create, remove, change or inspect a user's home
    directory. It's primarily a command interfacing with
    <citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    which manages home directories of users.</para>

    <para>Home directories managed by <filename>systemd-homed.service</filename> are self-contained, and thus
    include the user's full metadata record in the home's data storage itself, making them easy to migrate
    between machines. In particular, a home directory describes a matching user record, and every user record
    managed by <filename>systemd-homed.service</filename> also implies existence and encapsulation of a home
    directory. The user account and home directory become the same concept.</para>

    <para>The following backing storage mechanisms are supported:</para>

    <itemizedlist>
      <listitem><para>An individual LUKS2 encrypted loopback file for a user, stored in
      <filename>/home/*.home</filename>. At login the file system contained in this files is mounted, after
      the LUKS2 encrypted volume has been attached. The user's password is identical to the encryption
      passphrase of the LUKS2 volume. Access to data without preceding user authentication is thus not
      possible, even for the system administrator. This storage mechanism provides the strongest data
      security and is thus recommended.</para></listitem>

      <listitem><para>Similar, but the LUKS2 encrypted file system is located on regular block device, such
      as an USB storage stick. In this mode home directories and all data they include are nicely migratable
      between machines, simply by plugging the USB stick into different systems at different
      times.</para></listitem>

      <listitem><para>An encrypted directory using <literal>fscrypt</literal> on file systems that support it
      (at the moment this is primarily <literal>ext4</literal>), located in
      <filename>/home/*.homedir</filename>. This mechanism also provides encryption, but substantially
      weaker than LUKS2, as most file system metadata is unprotected. Moreover
      it currently does not support changing user passwords once the home directory has been
      created.</para></listitem>

      <listitem><para>A <literal>btrfs</literal> subvolume for each user, also located in
      <filename>/home/*.homedir</filename>. This provides no encryption, but good quota
      support.</para></listitem>

      <listitem><para>A regular directory for each user, also located in
      <filename>/home/*.homedir</filename>. This provides no encryption, but is a suitable fallback
      available on all machines, even where LUKS2, <literal>fscrypt</literal> or <literal>btrfs</literal>
      support is not available.</para></listitem>

      <listitem><para>An individual Windows file share (CIFS) for each user.</para></listitem>
    </itemizedlist>

    <para>Note that <filename>systemd-homed.service</filename> and <command>homectl</command> will not manage
    "classic" UNIX user accounts as created with <citerefentry
    project='man-pages'><refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum></citerefentry> or
    similar tools. In particular, this functionality is not suitable for managing system users (i.e. users
    with a UID below 1000) but is exclusive to regular ("human") users.</para>

    <para>Note that users/home directories managed via <command>systemd-homed.service</command> do not show
    up in <filename>/etc/passwd</filename> and similar files, they are synthesized via glibc NSS during
    runtime. They are thus resolvable and may be enumerated via the <citerefentry
    project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    tool.</para>

    <para>This tool interfaces directly with <filename>systemd-homed.service</filename>, and may execute
    specific commands on the home directories it manages. Since every home directory managed that way also
    defines a JSON user and group record these home directories may also be inspected and enumerated via
    <citerefentry><refentrytitle>userdbctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>

    <para>Home directories managed by <filename>systemd-homed.service</filename> are usually in one of two
    states, or in a transition state between them: when <literal>active</literal> they are unlocked and
    mounted, and thus accessible to the system and its programs; when <literal>inactive</literal> they are
    not mounted and thus not accessible. Activation happens automatically at login of the user and usually
    can only complete after a password (or other authentication token) has been supplied. Deactivation
    happens after the user fully logged out. A home directory remains active as long as the user is logged in
    at least once, i.e. has at least one login session. When the user logs in a second time simultaneously
    the home directory remains active. It is deactivated only after the last of the user's sessions
    ends.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following general options are understood (further options that control the various properties
    of user records managed by <filename>systemd-homed.service</filename> are documented further
    down):</para>

    <variablelist>

      <varlistentry>
        <term><option>--identity=</option><replaceable>FILE</replaceable></term>

        <listitem><para>Read the user's JSON record from the specified file. If passed as
        <literal>-</literal> read the user record from standard input. The supplied JSON object must follow
        the structure documented in <ulink url="https://systemd.io/USER_RECORD">JSON User Records</ulink>.
        This option may be used in conjunction with the <command>create</command> and
        <command>update</command> commands (see below), where it allows configuring the user record in JSON
        as-is, instead of setting the individual user record properties (see below).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--json=</option><replaceable>FORMAT</replaceable></term>
        <term><option>-J</option></term>

        <listitem><para>Controls whether to output the user record in JSON format, if the
        <command>inspect</command> command (see below) is used. Takes one of <literal>pretty</literal>,
        <literal>short</literal> or <literal>off</literal>. If <literal>pretty</literal> human-friendly
        whitespace and newlines are inserted in the output to make the JSON data more readable. If
        <literal>short</literal> all superfluous whitespace is suppressed. If <literal>off</literal> (the
        default) the user information is not shown in JSON format but in a friendly human readable formatting
        instead. The <option>-J</option> option picks <literal>pretty</literal> when run interactively and
        <literal>short</literal> otherwise.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--export-format=</option><replaceable>FORMAT</replaceable></term>
        <term><option>-E</option></term>
        <term><option>-EE</option></term>

        <listitem><para>When used with the <command>inspect</command> verb in JSON mode (see above) may be
        used to suppress certain aspects of the JSON user record on output. Specifically, if
        <literal>stripped</literal> format is used the binding and runtime fields of the record are
        removed. If <literal>minimal</literal> format is used the cryptographic signature is removed too. If
        <literal>full</literal> format is used the full JSON record is shown (this is the default). This
        option is useful for copying an existing user record to a different system in order to create a
        similar user there with the same settings. Specifically: <command>homectl inspect -EE | ssh
        root@othersystem homectl create -i-</command> may be used as simple command line for replicating a
        user on another host. <option>-E</option> is equivalent to <option>-j --export-format=stripped</option>,
        <option>-EE</option> to <option>-j --export-format=minimal</option>. Note that when replicating user
        accounts user records acquired in <literal>stripped</literal> mode will retain the original
        cryptographic signatures and thus may only be modified when the private key to update them is available
        on the destination machine. When replicating users in <literal>minimal</literal> mode, the signature
        is removed during the replication and thus the record will be implicitly signed with the key of the destination
        machine and may be updated there without any private key replication.</para></listitem>
      </varlistentry>

      <xi:include href="user-system-options.xml" xpointer="host" />
      <xi:include href="user-system-options.xml" xpointer="machine" />

      <xi:include href="standard-options.xml" xpointer="no-pager" />
      <xi:include href="standard-options.xml" xpointer="no-legend" />
      <xi:include href="standard-options.xml" xpointer="no-ask-password" />
      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>User Record Properties</title>

    <para>The following options control various properties of the user records/home directories that
    <filename>systemd-homed.service</filename> manages. These switches may be used in conjunction with the
    <command>create</command> and <command>update</command> commands for configuring various aspects of the
    home directory and the user account:</para>

    <variablelist>

      <varlistentry>
        <term><option>--real-name=</option><replaceable>NAME</replaceable></term>
        <term><option>-c</option> <replaceable>NAME</replaceable></term>

        <listitem><para>The real name for the user. This corresponds with the GECOS field on classic UNIX NSS
        records.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--realm=</option><replaceable>REALM</replaceable></term>

        <listitem><para>The realm for the user. The realm associates a user with a specific organization or
        installation, and allows distuingishing users of the same name defined in different contexts. The
        realm can be any string that also qualifies as valid DNS domain name, and it is recommended to use
        the organization's or installation's domain name for this purpose, but this is not enforced nor
        required. On each system only a single user of the same name may exist, and if a user with the same
        name and realm is seen it is assumed to refer to the same user while a user with the same name but
        different realm is considered a different user. Note that this means that two users sharing the same
        name but with distinct realms are not allowed on the same system. Assigning a realm to a user is
        optional.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--email-address=</option><replaceable>EMAIL</replaceable></term>

        <listitem><para>Takes an electronic mail address to associate with the user. On log-in the
        <varname>$EMAIL</varname> environment variable is initialized from this value.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--location=</option><replaceable>TEXT</replaceable></term>

        <listitem><para>Takes location specification for this user. This is free-form text, which might or
        might not be usable by geo-location applications. Example: <option>--location="Berlin,
        Germany"</option> or <option>--location="Basement, Room 3a"</option></para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--icon-name=</option><replaceable>ICON</replaceable></term>

        <listitem><para>Takes an icon name to associate with the user, following the scheme defined by the <ulink
        url="https://standards.freedesktop.org/icon-naming-spec/icon-naming-spec-latest.html">Icon Naming
        Specification</ulink>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--home-dir=</option><replaceable>PATH</replaceable></term>
        <term><option>-d</option><replaceable>PATH</replaceable></term>

        <listitem><para>Takes a path to use as home directory for the user. Note that this is the directory
        the user's home directory is mounted to while the user is logged in. This is not where the user's
        data is actually stored, see <option>--image-path=</option> for that. If not specified defaults to
        <filename>/home/$USER</filename>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--uid=</option><replaceable>UID</replaceable></term>

        <listitem><para>Takes a preferred numeric UNIX UID to assign this user. If a user is to be created
        with the specified UID and it is already taken by a different user on the local system then creation
        of the home directory is refused. Note though, if after creating the home directory it is used on a
        different system and the configured UID is taken by another user there, then
        <command>systemd-homed</command> may assign the user a different UID on that system. The specified
        UID must be outside of the system user range. It is recommended to use the 60001…60513 UID range for
        this purpose. If not specified, the UID is automatically picked. If the home directory is found to be
        owned by a different UID when logging in, the home directory and everything underneath it will have
        its ownership changed automatically before login completes.</para>

        <para>Note that users managed by <command>systemd-homed</command> always have a matching group
        associated with the same name as well as a GID matching the UID of the user. Thus, configuring the
        GID separately is not permitted.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--member-of=</option><replaceable>GROUP</replaceable></term>
        <term><option>-G</option> <replaceable>GROUP</replaceable></term>

        <listitem><para>Takes a comma-separated list of auxiliary UNIX groups this user shall belong
        to. Example: <option>--member-of=wheel</option> to provide the user with administrator
        privileges. Note that <command>systemd-homed</command> does not manage any groups besides a group
        matching the user in name and numeric UID/GID. Thus any groups listed here must be registered
        independently, for example with <citerefentry
        project='man-pages'><refentrytitle>groupadd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
        Any non-existent groups are ignored. This option may be used more than once, in which case all
        specified group lists are combined. If the user is currently a member of a group which is not listed,
        the user will be removed from the group.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--skel=</option><replaceable>PATH</replaceable></term>

        <listitem><para>Takes a file system path to a directory. Specifies the skeleton directory to
        initialize the home directory with. All files and directories in the specified path are copied into
        any newly create home directory. If not specified defaults to <filename>/etc/skel/</filename>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--shell=</option><replaceable>SHELL</replaceable></term>

        <listitem><para>Takes a file system path. Specifies the shell binary to execute on terminal
        logins. If not specified defaults to <filename>/bin/bash</filename>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--setenv=</option><replaceable>VARIABLE</replaceable>=<replaceable>VALUE</replaceable></term>

        <listitem><para>Takes an environment variable assignment to set for all user processes. Note that a
        number of other settings also result in environment variables to be set for the user, including
        <option>--email=</option>, <option>--timezone=</option> and <option>--language=</option>. May be used
        multiple times to set multiple environment variables.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--timezone=</option><replaceable>TIMEZONE</replaceable></term>

        <listitem><para>Takes a time zone location name that sets the timezone for the specified user. When
        the user logs in the <varname>$TZ</varname> environment variable is initialized from this
        setting. Example: <option>--timezone=Europe/Amsterdam</option> will result in the environment
        variable <literal>TZ=:Europe/Amsterdam</literal>. (<literal>:</literal> is used intentionally as part
        of the timezone specification, see
        <citerefentry><refentrytitle>tzset</refentrytitle><manvolnum>3</manvolnum></citerefentry>.)
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--language=</option><replaceable>LANG</replaceable></term>

        <listitem><para>Takes a specifier indicating the preferred language of the user. The
        <varname>$LANG</varname> environment variable is initialized from this value on login, and thus a
        value suitable for this environment variable is accepted here, for example
        <option>--language=de_DE.UTF8</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--ssh-authorized-keys=</option><replaceable>KEYS</replaceable></term>
        <listitem><para>Either takes a SSH authorized key line to associate with the user record or a
        <literal>@</literal> character followed by a path to a file to read one or more such lines from. SSH
        keys configured this way are made available to SSH to permit access to this home directory and user
        record. This option may be used more than once to configure multiple SSH keys.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--pkcs11-token-uri=</option><replaceable>URI</replaceable></term>
        <listitem><para>Takes an RFC 7512 PKCS#11 URI referencing a security token (e.g. YubiKey or PIV
        smartcard) that shall be able to unlock the user account. The security token URI should reference a
        security token with exactly one pair of X.509 certificate and private key. A random secret key is
        then generated, encrypted with the public key of the X.509 certificate, and stored as part of the
        user record. At login time it is decrypted with the PKCS#11 module and then used to unlock the
        account and associated resources. See below for an example how to set up authentication with a
        security token.</para>

        <para>Instead of a valid PKCS#11 URI, the special strings <literal>list</literal> and
        <literal>auto</literal> may be specified. If <literal>list</literal> is passed, a brief table of
        suitable, currently plugged in PKCS#11 hardware tokens is shown, along with their URIs. If
        <literal>auto</literal> is passed, a suitable PKCS#11 hardware token is automatically selected (this
        operation will fail if there isn't exactly one suitable token discovered). The latter is a useful
        shortcut for the most common case where a single PKCS#11 hardware token is plugged in.</para>

        <para>Note that many hardware security tokens implement both PKCS#11/PIV and FIDO2 with the
        <literal>hmac-secret</literal> extension (for example: the YubiKey 5 series), as supported with the
        <option>--fido2-device=</option> option below. Both mechanisms are similarly powerful, though FIDO2
        is the more modern technology. PKCS#11/PIV tokens have the benefit of being recognizable before
        authentication and hence can be used for implying the user identity to use for logging in, which
        FIDO2 does not allow. PKCS#11/PIV devices generally require initialization (i.e. storing a
        private/public key pair on them, see example below) before they can be used; FIDO2 security tokens
        generally do not required that, and work out of the box.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--fido2-device=</option><replaceable>PATH</replaceable></term>

        <listitem><para>Takes a path to a Linux <literal>hidraw</literal> device
        (e.g. <filename>/dev/hidraw1</filename>), referring to a FIDO2 security token implementing the
        <literal>hmac-secret</literal> extension, that shall be able to unlock the user account. If used, a
        random salt value is generated on the host, which is passed to the FIDO2 device, which calculates a
        HMAC hash of it, keyed by its internal secret key. The result is then used as key for unlocking the
        user account. The random salt is included in the user record, so that whenever authentication is
        needed it can be passed again to the FIDO2 token, to retrieve the actual key.</para>

        <para>Instead of a valid path to a FIDO2 <literal>hidraw</literal> device the special strings
        <literal>list</literal> and <literal>auto</literal> may be specified. If <literal>list</literal> is
        passed, a brief table of suitable discovered FIDO2 devices is shown. If <literal>auto</literal> is
        passed, a suitable FIDO2 token is automatically selected, if exactly one is discovered. The latter is
        a useful shortcut for the most common case where a single FIDO2 hardware token is plugged in.</para>

        <para>Note that FIDO2 devices suitable for this option must implement the
        <literal>hmac-secret</literal> extension. Most current devices (such as the YubiKey 5 series) do. If
        the extension is not implemented the device cannot be used for unlocking home directories.</para>

        <para>Note that many hardware security tokens implement both FIDO2 and PKCS#11/PIV (and thus may be
        used with either <option>--fido2-device=</option> or <option>--pkcs11-token-uri=</option>), for a
        discussion see above.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--recovery-key=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Accepts a boolean argument. If enabled a recovery key is configured for the
        account. A recovery key is a computer generated access key that may be used to regain access to an
        account if the password has been forgotten or the authentication token lost. The key is generated and
        shown on screen, and should be printed or otherwise transferred to a secure location. A recovery key
        may be entered instead of a regular password to unlock the account.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--locked=</option><replaceable>BOOLEAN</replaceable></term>

        <listitem><para>Takes a boolean argument. Specifies whether this user account shall be locked. If
        true logins into this account are prohibited, if false (the default) they are permitted (of course,
        only if authorization otherwise succeeds).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--not-before=</option><replaceable>TIMESTAMP</replaceable></term>
        <term><option>--not-after=</option><replaceable>TIMESTAMP</replaceable></term>

        <listitem><para>These options take a timestamp string, in the format documented in
        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> and
        configures points in time before and after logins into this account are not
        permitted.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--rate-limit-interval=</option><replaceable>SECS</replaceable></term>
        <term><option>--rate-limit-burst=</option><replaceable>NUMBER</replaceable></term>

        <listitem><para>Configures a rate limit on authentication attempts for this user. If the user
        attempts to authenticate more often than the specified number, on a specific system, within the
        specified time interval authentication is refused until the time interval passes. Defaults to 10
        times per 1min.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--password-hint=</option><replaceable>TEXT</replaceable></term>

        <listitem><para>Takes a password hint to store alongside the user record. This string is stored
        accessible only to privileged users and the user itself and may not be queried by other users.
        Example: <option>--password-hint="My first pet's name"</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--enforce-password-policy=</option><replaceable>BOOL</replaceable></term>
        <term><option>-P</option></term>

        <listitem><para>Takes a boolean argument. Configures whether to enforce the system's password policy
        for this user, regarding quality and strength of selected passwords. Defaults to
        on. <option>-P</option> is short for
        <option>---enforce-password-policy=no</option>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--password-change-now=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Takes a boolean argument. If true the user is asked to change their password on next
        login.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--password-change-min=</option><replaceable>TIME</replaceable></term>
        <term><option>--password-change-max=</option><replaceable>TIME</replaceable></term>
        <term><option>--password-change-warn=</option><replaceable>TIME</replaceable></term>
        <term><option>--password-change-inactive=</option><replaceable>TIME</replaceable></term>

        <listitem><para>Each of these options takes a time span specification as argument (in the syntax
        documented in
        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>) and
        configures various aspects of the user's password expiration policy. Specifically,
        <option>--password-change-min=</option> configures how much time has to pass after changing the
        password of the user until the password may be changed again. If the user tries to change their
        password before this time passes the attempt is refused. <option>--password-change-max=</option>
        configures how soon after it has been changed the password expires and needs to be changed again.
        After this time passes logging in may only proceed after the password is changed.
        <option>--password-change-warn=</option> specifies how much earlier than then the time configured
        with <option>--password-change-max=</option> the user is warned at login to change their password as
        it will expire soon. Finally <option>--password-change-inactive=</option> configures the time which
        has to pass after the password as expired until the user is not permitted to log in or change the
        password anymore. Note that these options only apply to password authentication, and do not apply to
        other forms of authentication, for example PKCS#11-based security token
        authentication.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--disk-size=</option><replaceable>BYTES</replaceable></term>
        <listitem><para>Either takes a size in bytes as argument (possibly using the usual K, M, G, …
        suffixes for 1024 base values), or a percentage value and configures the disk space to assign to the
        user. If a percentage value is specified (i.e. the argument suffixed with <literal>%</literal>) it is
        taken relative to the available disk space of the backing file system. If the LUKS2 backend is used
        this configures the size of the loopback file and file system contained therein. For the other
        storage backends configures disk quota using the filesystem's native quota logic, if available. If
        not specified, defaults to 85% of the available disk space for the LUKS2 backend and to no quota for
        the others.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--access-mode=</option><replaceable>MODE</replaceable></term>

        <listitem><para>Takes a UNIX file access mode written in octal. Configures the access mode of the
        home directory itself. Note that this is only used when the directory is first created, and the user
        may change this any time afterwards. Example:
        <option>--access-mode=0700</option></para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--umask=</option><replaceable>MASK</replaceable></term>

        <listitem><para>Takes the access mode mask (in octal syntax) to apply to newly created files and
        directories of the user ("umask"). If set this controls the initial umask set for all login sessions of
        the user, possibly overriding the system's defaults.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--nice=</option><replaceable>NICE</replaceable></term>

        <listitem><para>Takes the numeric scheduling priority ("nice level") to apply to the processes of the user at login
        time. Takes a numeric value in the range -20 (highest priority) to 19 (lowest priority).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--rlimit=</option><replaceable>LIMIT</replaceable>=<replaceable>VALUE</replaceable><optional>:<replaceable>VALUE</replaceable></optional></term>

        <listitem><para>Allows configuration of resource limits for processes of this user, see <citerefentry
        project='man-pages'><refentrytitle>getrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
        for details. Takes a resource limit name (e.g. <literal>LIMIT_NOFILE</literal>) followed by an equal
        sign, followed by a numeric limit. Optionally, separated by colon a second numeric limit may be
        specified. If two are specified this refers to the soft and hard limits, respectively. If only one
        limit is specified the setting sets both limits in one.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--tasks-max=</option><replaceable>TASKS</replaceable></term>

        <listitem><para>Takes a non-zero unsigned integer as argument. Configures the maximum numer of tasks
        (i.e. threads, where each process is at least one thread) the user may have at any given time. This
        limit applies to all tasks forked off the user's sessions, even if they change user identity via
        <citerefentry project='man-pages'><refentrytitle>su</refentrytitle><manvolnum>1</manvolnum></citerefentry>
        or a similar tool. Use <option>--rlimit=LIMIT_NPROC=</option> to place a limit on the tasks actually
        running under the UID of the user, thus excluding any child processes that might have changed user
        identity. This controls the <varname>TasksMax=</varname> setting of the per-user systemd slice unit
        <filename>user-$UID.slice</filename>. See
        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for further details.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--memory-high=</option><replaceable>BYTES</replaceable></term>
        <term><option>--memory-max=</option><replaceable>BYTES</replaceable></term>

        <listitem><para>Set a limit on the memory a user may take up on a system at any given time in bytes
        (the usual K, M, G, … suffixes are supported, to the base of 1024). This includes all memory used by
        the user itself and all processes they forked off that changed user credentials. This controls the
        <varname>MemoryHigh=</varname> and <varname>MemoryMax=</varname> settings of the per-user systemd
        slice unit <filename>user-$UID.slice</filename>. See
        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for further details.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--cpu-weight=</option><replaceable>WEIGHT</replaceable></term>
        <term><option>--io-weight=</option><replaceable>WEIGHT</replaceable></term>

        <listitem><para>Set CPU and IO scheduling weights of the processes of the user, including those of
        processes forked off by the user that changed user credentials. Takes a numeric value in the range
        1…10000. This controls the <varname>CPUWeight=</varname> and <varname>IOWeight=</varname> settings of
        the per-user systemd slice unit <filename>user-$UID.slice</filename>. See
        <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for further details.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--storage=</option><replaceable>STORAGE</replaceable></term>

        <listitem><para>Selects the storage mechanism to use for this home directory. Takes one of
        <literal>luks</literal>, <literal>fscrypt</literal>, <literal>directory</literal>,
        <literal>subvolume</literal>, <literal>cifs</literal>. For details about these mechanisms, see
        above. If a new home directory is created and the storage type is not specifically specified,
        <citerefentry><refentrytitle>homed.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        defines which default storage to use.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--image-path=</option><replaceable>PATH</replaceable></term>

        <listitem><para>Takes a file system path. Configures where to place the user's home directory. When
        LUKS2 storage is used refers to the path to the loopback file, otherwise to the path to the home
        directory (which may be in <filename>/home/</filename> or any other accessible filesystem). When
        unspecified defaults to <filename>/home/$USER.home</filename> when LUKS storage is used and
        <filename>/home/$USER.homedir</filename> for the other storage mechanisms. Not defined for the
        <literal>cifs</literal> storage mechanism. To use LUKS2 storage on a regular block device (for
        example a USB stick) pass the path to the block device here. Specifying the path to a directory here
        when using LUKS2 storage is not allowed. Similar, specifying the path to a regular file or device
        node is not allowed if any of the other storage backends are used.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--fs-type=</option><replaceable>TYPE</replaceable></term>

        <listitem><para>When LUKS2 storage is used configures the file system type to use inside the home
        directory LUKS2 container. One of <literal>btrfs</literal>, <literal>ext4</literal>,
        <literal>xfs</literal>. If not specified
        <citerefentry><refentrytitle>homed.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        defines which default file system type to use. Note that <literal>xfs</literal> is not recommended as
        its support for file system resizing is too limited.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--luks-discard=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>When LUKS2 storage is used configures whether to enable the
        <literal>discard</literal> feature of the file system. If enabled the file system on top of the LUKS2
        volume will report empty block information to LUKS2 and the loopback file below, ensuring that empty
        space in the home directory is returned to the backing file system below the LUKS2 volume, resulting
        in a "sparse" loopback file. This option mostly defaults to off, since this permits over-committing
        home directories which results in I/O errors if the underlying file system runs full while the upper
        file system wants to allocate a block. Such I/O errors are generally not handled well by file systems
        nor applications. When LUKS2 storage is used on top of regular block devices (instead of on top a
        loopback file) the discard logic defaults to on.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--luks-offline-discard=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Similar to <option>--luks-discard=</option>, controls the trimming of the file
        system. However, while <option>--luks-discard=</option> controls what happens when the home directory
        is active, <option>--luks-offline-discard=</option> controls what happens when it becomes inactive,
        i.e. whether to trim/allocate the storage when deactivating the home directory. This option defaults
        to on, to ensure disk space is minimized while a user is not logged in.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--luks-cipher=</option><replaceable>CIPHER</replaceable></term>
        <term><option>--luks-cipher-mode=</option><replaceable>MODE</replaceable></term>
        <term><option>--luks-volume-key-size=</option><replaceable>BITS</replaceable></term>
        <term><option>--luks-pbkdf-type=</option><replaceable>TYPE</replaceable></term>
        <term><option>--luks-pbkdf-hash-algorithm=</option><replaceable>ALGORITHM</replaceable></term>
        <term><option>--luks-pbkdf-time-cost=</option><replaceable>SECONDS</replaceable></term>
        <term><option>--luks-pbkdf-memory-cost=</option><replaceable>BYTES</replaceable></term>
        <term><option>--luks-pbkdf-parallel-threads=</option><replaceable>THREADS</replaceable></term>

        <listitem><para>Configures various cryptographic parameters for the LUKS2 storage mechanism. See
        <citerefentry
        project='man-pages'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        for details on the specific attributes.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--nosuid=</option><replaceable>BOOL</replaceable></term>
        <term><option>--nodev=</option><replaceable>BOOL</replaceable></term>
        <term><option>--noexec=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Configures the <literal>nosuid</literal>, <literal>nodev</literal> and
        <literal>noexec</literal> mount options for the home directories. By default <literal>nodev</literal>
        and <literal>nosuid</literal> are on, while <literal>noexec</literal> is off. For details about these
        mount options see <citerefentry
        project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--cifs-domain=</option><replaceable>DOMAIN</replaceable></term>
        <term><option>--cifs-user-name=</option><replaceable>USER</replaceable></term>
        <term><option>--cifs-service=</option><replaceable>SERVICE</replaceable></term>

        <listitem><para>Configures the Windows File Sharing (CIFS) domain and user to associate with the home
        directory/user account, as well as the file share ("service") to mount as directory. The latter is used when
        <literal>cifs</literal> storage is selected.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--stop-delay=</option><replaceable>SECS</replaceable></term>

        <listitem><para>Configures the time the per-user service manager shall continue to run after the all
        sessions of the user ended. The default is configured in
        <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> (for
        home directories of LUKS2 storage located on removable media this defaults to 0 though). A longer
        time makes sure quick, repetitive logins are more efficient as the user's service manager doesn't
        have to be started every time.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--kill-processes=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Configures whether to kill all processes of the user on logout. The default is
        configured in
        <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--auto-login=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Takes a boolean argument. Configures whether the graphical UI of the system should
        automatically log this user in if possible. Defaults to off. If less or more than one user is marked
        this way automatic login is disabled.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Commands</title>

    <para>The following commands are understood:</para>

    <variablelist>

      <varlistentry>
        <term><command>list</command></term>

        <listitem><para>List all home directories (along with brief details) currently managed by
        <filename>systemd-homed.service</filename>. This command is also executed if none is specified on the
        command line. (Note that the list of users shown by this command does not include users managed by
        other subsystems, such as system users or any traditional users listed in
        <filename>/etc/passwd</filename>.)</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>activate</command> <replaceable>USER</replaceable> [<replaceable>USER…</replaceable>]</term>

        <listitem><para>Activate one or more home directories. The home directories of each listed user will
        be activated and made available under their mount points (typically in
        <filename>/home/$USER</filename>). Note that any home activated this way stays active indefinitely,
        until it is explicitly deactivated again (with <command>deactivate</command>, see below), or the user
        logs in and out again and it thus is deactivated due to the automatic deactivation-on-logout
        logic.</para>

        <para>Activation of a home directory involves various operations that depend on the selected storage
        mechanism. If the LUKS2 mechanism is used, this generally involves: inquiring the user for a
        password, setting up a loopback device, validating and activating the LUKS2 volume, checking the file
        system, mounting the file system, and potentially changing the ownership of all included files to the
        correct UID/GID.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>deactivate</command> <replaceable>USER</replaceable> [<replaceable>USER…</replaceable>]</term>

        <listitem><para>Deactivate one or more home directories. This undoes the effect of
        <command>activate</command>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>inspect</command> <replaceable>USER</replaceable> [<replaceable>USER…</replaceable>]</term>

        <listitem><para>Show various details about the specified home directories. This shows various
        information about the home directory and its user account, including runtime data such as current
        state, disk use and similar. Combine with <option>--json=</option> to show the detailed JSON user
        record instead, possibly combined with <option>--export-format=</option> to suppress certain aspects
        of the output.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>authenticate</command> <replaceable>USER</replaceable> [<replaceable>USER…</replaceable>]</term>

        <listitem><para>Validate authentication credentials of a home directory. This queries the caller for
        a password (or similar) and checks that it correctly unlocks the home directory. This leaves the home
        directory in the state it is in, i.e. it leaves the home directory in inactive state if it was
        inactive before, and in active state if it was active before.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>create</command> <replaceable>USER</replaceable></term>
        <term><command>create</command> <option>--identity=</option><replaceable>PATH</replaceable> <optional><replaceable>USER</replaceable></optional></term>

        <listitem><para>Create a new home directory/user account of the specified name. Use the various
        user record property options (as documented above) to control various aspects of the home directory
        and its user accounts.</para>

        <para>The specified user name should follow the strict syntax described on <ulink
        url="https://systemd.io/USER_NAMES">User/Group Name Syntax</ulink>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>remove</command> <replaceable>USER</replaceable></term>

        <listitem><para>Remove a home directory/user account. This will remove both the home directory's user
        record and the home directory itself, and thus delete all files and directories owned by the
        user.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>update</command> <replaceable>USER</replaceable></term>
        <term><command>update</command> <option>--identity=</option><replaceable>PATH</replaceable> <optional><replaceable>USER</replaceable></optional></term>

        <listitem><para>Update a home directory/user account. Use the various user record property options
        (as documented above) to make changes to the account, or alternatively provide a full, updated JSON
        user record via the <option>--identity=</option> option.</para>

        <para>Note that changes to user records not signed by a cryptographic private key available locally
        are not permitted, unless <option>--identity=</option> is used with a user record that is already
        correctly signed by a recognized private key.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>passwd</command> <replaceable>USER</replaceable></term>

        <listitem><para>Change the password of the specified home directory/user account.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>resize</command> <replaceable>USER</replaceable> <replaceable>BYTES</replaceable></term>

        <listitem><para>Change the disk space assigned to the specified home directory. If the LUKS2 storage
        mechanism is used this will automatically resize the loopback file and the file system contained
        within. Note that if <literal>ext4</literal> is used inside of the LUKS2 volume, it is necessary to
        deactivate the home directory before shrinking it (i.e the user has to log out). Growing can be done
        while the home directory is active. If <literal>xfs</literal> is used inside of the LUKS2 volume the
        home directory may not be shrunk whatsoever. On all three of <literal>ext4</literal>,
        <literal>xfs</literal> and <literal>btrfs</literal> the home directory may be grown while the user is
        logged in, and on the latter also shrunk while the user is logged in. If the
        <literal>subvolume</literal>, <literal>directory</literal>, <literal>fscrypt</literal> storage
        mechanisms are used, resizing will change file system quota.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>lock</command> <replaceable>USER</replaceable></term>

        <listitem><para>Temporarily suspend access to the user's home directory and remove any associated
        cryptographic keys from memory. Any attempts to access the user's home directory will stall until the
        home directory is unlocked again (i.e. re-authenticated). This functionality is primarily intended to
        be used during system suspend to make sure the user's data cannot be accessed until the user
        re-authenticates on resume. This operation is only defined for home directories that use the LUKS2
        storage mechanism.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>unlock</command> <replaceable>USER</replaceable></term>

        <listitem><para>Resume access to the user's home directory again, undoing the effect of
        <command>lock</command> above. This requires authentication of the user, as the cryptographic keys
        required for access to the home directory need to be reacquired.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>lock-all</command></term>

        <listitem><para>Execute the <command>lock</command> command on all suitable home directories at
        once. This operation is generally executed on system suspend (i.e. by <command>systemctl
        suspend</command> and related commands), to ensure all active user's cryptographic keys for accessing
        their home directories are removed from memory.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>with</command> <replaceable>USER</replaceable> <replaceable>COMMAND…</replaceable></term>

        <listitem><para>Activate the specified user's home directory, run the specified command (under the
        caller's identity, not the specified user's) and deactivate the home directory afterwards again
        (unless the user is logged in otherwise). This command is useful for running privileged backup
        scripts and such, but requires authentication with the user's credentials in order to be able to
        unlock the user's home directory.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure code otherwise.</para>
  </refsect1>

  <xi:include href="less-variables.xml" />

  <refsect1>
    <title>Examples</title>

    <example>
      <title>Create a user <literal>waldo</literal> in the administrator group <literal>wheel</literal>, and
      assign 500 MiB disk space to them.</title>

      <programlisting>homectl create waldo --real-name="Waldo McWaldo" -G wheel --disk-size=500M</programlisting>
    </example>

    <example>
      <title>Create a user <literal>wally</literal> on a USB stick, and assign a maximum of 500 concurrent
      tasks to them.</title>

      <programlisting>homectl create wally --real-name="Wally McWally" --image-path=/dev/disk/by-id/usb-SanDisk_Ultra_Fit_476fff954b2b5c44-0:0 --tasks-max=500</programlisting>
    </example>

    <example>
      <title>Change nice level of user <literal>odlaw</literal> to +5 and make sure the environment variable
      <varname>$SOME</varname> is set to the string <literal>THING</literal> for them on login.</title>

      <programlisting>homectl update odlaw --nice=5 --setenv=SOME=THING</programlisting>
    </example>

    <example>
      <title>Set up authentication with a YubiKey security token using PKCS#11/PIV:</title>

      <programlisting># Clear the Yubikey from any old keys (careful!)
ykman piv reset

# Generate a new private/public key pair on the device, store the public key in 'pubkey.pem'.
ykman piv generate-key -a RSA2048 9d pubkey.pem

# Create a self-signed certificate from this public key, and store it on the device.
ykman piv generate-certificate --subject "Knobelei" 9d pubkey.pem

# We don't need the public key on disk anymore
rm pubkey.pem

# Allow the security token to unlock the account of user 'lafcadio'.
homectl update lafcadio --pkcs11-token-uri=auto</programlisting>
    </example>

    <example>
      <title>Set up authentication with a FIDO2 security token:</title>

      <programlisting># Allow a FIDO2 security token to unlock the account of user 'nihilbaxter'.
homectl update nihilbaxter --fido2-device=auto</programlisting>
    </example>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>homed.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>userdbctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>