* When operating on disk images via the --image= switch of various
tools (such as systemd-nspawn or systemd-dissect), or when udev finds
no 'root=' parameter on the kernel command line, and multiple
suitable root or /usr/ partitions exist in the image, then a simple
comparison inspired by strverscmp() is done on the GPT partition
label, and the newest partition is picked. This permits a simple and
generic whole-file-system A/B update logic where new operating system
versions are dropped into partitions whose label is then updated with
a matching version identifier.
* systemd-sysusers now supports querying the passwords to set for the
users it creates via the "credentials" logic introduced in v247: the
passwd.hashed-password.<user> and passwd.plaintext-password.<user>
credentials are consulted for the password to use (either in UNIX
hashed form, or literally). By default these credentials are inherited
down from PID1 (which in turn imports it from a container manager if
there is one). This permits easy configuration of user passwords
during first boot. Example:
# systemd-nspawn -i foo.raw --volatile=yes --set-credential=passwd.plaintext-password.root:foo
Note that systemd-sysusers operates in purely additive mode: it
executes no operation if the declared users already exist, and hence
doesn't set any passwords as effect of the command line above if the
specified root user exists already in the image. (Note that
--volatile=yes ensures it doesn't, though.)
* systemd-firstboot now also supports querying various system
parameters via the credential subsystems. Thus, as above this may be
used to initialize important system parameters on first boot of
previously unprovisioned images (i.e. images with a mostly empty
* PID 1 may now show both the unit name and the unit description
strings in its status output during boot. This may be configured with
StatusUnitFormat=combined in system.conf or
systemd.status-unit-format=combined on the kernel command line.
* The systemd-machine-id-setup tool now supports a --image= switch for
provisioning a machine ID file into an OS disk image, similar to how
--root= operates on an OS file tree. This matches the existing switch
of the same name for systemd-tmpfiles, systemd-firstboot, and
* Similarly, systemd-repart gained support for the --image= switch too.
In combination with the existing --size= option, this makes the tool
particularly useful for easily growing disk images in a single
invocation, following the declarative rules included in the image
* systemd-repart's partition configuration files gained support for a
new switch MakeDirectories= which may be used to create arbitrary
directories inside file systems that are created, before registering
them in the partition table. This is useful in particular for root
partitions to create mount point directories for other partitions
included in the image. For example, a disk image that contains a
root, /home/, and /var/ partitions, may set MakeDirectories=yes to
create /home/ and /var/ as empty directories in the root file system
on its creation, so that the resulting image can be mounted
immediately, even in read-only mode.
* systemd-repart's CopyBlocks= setting gained support for the special
value "auto". If used, a suitable matching partition on the booted OS
is found as source to copy blocks from. This is useful when
implementing replicating installers, that are booted from one medium
and then stream their own root partition onto the target medium.
* systemd-repart's partition configuration files gained support for a
Flags=, a ReadOnly= and a NoAuto= setting, allowing control of these
GPT partition flags for the created partitions: this is useful for
marking newly created partitions as read-only, or as not being
subject for automatic mounting from creation on.
* The /etc/os-release file has been extended with two new (optional)
variables IMAGE_VERSION= and IMAGE_ID=, carrying identity and version
information for OS images that are updated comprehensively and
atomically as one image. Two new specifiers %M, %A now resolve to
these two fields in the various configuration options that resolve
* portablectl gained a new switch --extension= for enabling portable
service images with extensions that follow the extension image
concept introduced with v248, and thus allows layering multiple
images when setting up the root filesystem of the service.
* systemd-coredump will now extract ELF build-id information from
processes dumping core and include it in the coredump report.
Moreover, it will look for ELF .note.package sections with
distribution packaging meta-information about the crashing process.
This is useful to directly embed the rpm or deb (or any other)
package name and version in ELF files, making it easy to match
coredump reports with the specific package for which the software was
compiled. This is particularly useful on environments with ELF files
from multiple vendors, different distributions and versions, as is
common today in our containerized and sand-boxed world. For further
* A new udev hardware database has been added for FireWire devices
* The "net_id" built-in of udev has been updated with three
- PCI hotplug slot names on s390 systems are now parsed as
hexadecimal numbers. They were incorrectly parsed as decimal
previously, or ignored if the name was not a valid decimal
- PCI onboard indices up to 65535 are allowed. Previously, numbers
above 16383 were rejected. This primarily impacts s390 systems,
where values up to 65535 are used.
- Invalid characters in interface names are replaced with "_".
The new version of the net naming scheme is "v249". The previous
scheme can be selected via the "net.naming-scheme=v247" kernel
command line parameter.
* sd-bus' sd_bus_is_ready() and sd_bus_is_open() calls now accept a
NULL bus object, for which they will return false. Or in other words,
an unallocated bus connection is neither ready nor open.
* The sd-device API acquired a new API function
sd_device_get_usec_initialized() that returns the monotonic time when
the udev device first appeared in the database.
* sd-device gained a new APIs sd_device_trigger_with_uuid() and
sd_device_get_trigger_uuid(). The former is similar to
sd_device_trigger() but returns a randomly generated UUID that is
associated with the synthetic uevent generated by the call. This UUID
may be read from the sd_device object a monitor eventually receives,
via the sd_device_get_trigger_uuid(). This interface requires kernel
4.13 or above to work, and allows tracking a synthetic uevent through
the entire device management stack. The "udevadm trigger --settle"
logic has been updated to make use of this concept if available to
wait precisely for the uevents it generates. "udevadm trigger" also
gained a new parameter --uuid that prints the UUID for each generated
* sd-device also gained new APIs sd_device_new_from_ifname() and
sd_device_new_from_ifindex() for allocating an sd-device object for
the specified network interface. The former accepts an interface name
(either a primary or an alternative name), the latter an interface
* The native Journal protocol has been documented. Clients may talk
this as alternative to the classic BSD syslog protocol for locally
delivering log records to the Journal. The protocol has been stable
for a long time and in fact been implemented already in a variety
of alternative client libraries. This documentation makes the support
for that official:
* A new BPFProgram= setting has been added to service files. It may be
set to a path to a loaded kernel BPF program, i.e. a path to a bpffs
file, or a bind mount or symlink to one. This may be used to upload
and manage BPF programs externally and then hook arbitrary systemd
services into them.
* The "home.arpa" domain that has been officially declared as the
choice for domain for local home networks per RFC 8375 has been added
to the default NTA list of resolved, since DNSSEC is generally not
available on private domains.
* The CPUAffinity= setting of unit files now resolves "%" specifiers.
* A new ManageForeignRoutingPolicyRules= setting has been added to
.network files which may be used to exclude foreign-created routing
policy rules from systemd-networkd management.
* systemd-network-wait-online gained two new switches -4 and -6 that
may be used to tweak whether to wait for only IPv4 or only IPv6
* .network files gained a new RequiredFamilyForOnline= setting to
fine-tune whether to require an IPv4 or IPv6 address in order to
consider an interface "online".
* networkctl will now show an over-all "online" state in the per-link
* In .network files a new OutgoingInterface= setting has been added to
specify the output interface in bridge FDB setups.
* In .network files the Multipath group ID may now be configured for
[NextHop] entries, via the new Group= setting.
* The DHCP server logic configured in .network files gained a new
setting RelayTarget= that turns the server into a DHCP server relay.
The RelayAgentCircuitId= and RelayAgentRemoteId= settings may be used
to further tweak the DHCP relay behaviour.
* The DHCP server logic also gained a new ServerAddress= setting in
.network files that explicitly specifies the server IP address to
use. If not specified, the address is determined automatically, as
* The DHCP server logic in systemd-networkd gained support for static
DHCP leases, configurable via the [DHCPServerStaticLease]
section. This allows explicitly mapping specific MAC addresses to
fixed IP addresses and vice versa.
* The RestrictAddressFamilies= setting in service files now supports a
new special value "none". If specified sockets of all address
families will be made unavailable to services configured that way.
* systemd-fstab-generator and systemd-repart have been updated to
support booting from disks that carry only a /usr/ partition but no
root partition yet, and where systemd-repart can add it in on the
first boot. This is useful for implementing systems that ship with a
single /usr/ file system, and whose root file system shall be set up
and formatted on a LUKS-encrypted volume whose key is generated
locally (and possibly enrolled in the TPM) during the first boot.
* The [Address] section of .network files now accepts a new
RouteMetric= setting that configures the routing metric to use for
the prefix route created as effect of the address configuration.
Similarly, the [DHCPv6PrefixDelegation] and [IPv6Prefix] sections
gained matching settings for their prefix routes. (The option of the
same name in the [DHCPv6] section is moved to [IPv6AcceptRA], since
it conceptually belongs there; the old option is still understood for
* The DHCPv6 IAID and DUID are now explicitly configurable in .network
* A new udev property ID_NET_DHCP_BROADCAST on network interface
devices is now honoured by systemd-networkd, controlling whether to
issue DHCP offers via broadcasting. This is used to ensure that s390
layer 3 network interfaces work out-of-the-box with systemd-networkd.
* nss-myhostname and systemd-resolved will now synthesize address
records for a new special hostname "_outbound". The name will always
resolve to the local IP addresses most likely used for outbound
connections towards the default routes. On multi-homed hosts this is
useful to have a stable handle referring to "the" local IP address
that matters most, to the point where this is defined.
* The Discoverable Partition Specification has been updated with a new
GPT partition flag "grow-file-system" defined for its partition
types. Whenever partitions with this flag set are automatically
mounted (i.e. via systemd-gpt-auto-generator or the --image= switch
of systemd-nspawn or other tools; and as opposed to explicit mounting
via /etc/fstab), the file system within the partition is
automatically grown to the full size of the partition. If the file
system size already matches the partition size this flag has no
effect. Previously, this functionality has been available via the
explicit x-systemd.growfs mount option, and this new flag extends
this to automatically discovered mounts. A new GrowFileSystem=
setting has been added to systemd-repart drop-in files that allows
configuring this partition flag. This new flag defaults to on for
partitions automatically created by systemd-repart, except if they
are marked read-only. See the specification for further details:
* .network files gained a new setting RoutesToNTP= in the [DHCPv4]
section. If enabled (which is the default), and an NTP server address
is acquired through a DHCP lease on this interface an explicit route
to this address is created on this interface to ensure that NTP
traffic to the NTP server acquired on an interface is also routed
through that interface. The pre-existing RoutesToDNS= setting that
implements the same for DNS servers is now enabled by default.
* A pair of service settings SocketBindAllow= + SocketBindDeny= have
been added that may be used to restrict the network interfaces
sockets created by the service may be bound to. This is implemented
* A new ConditionFirmware= setting has been added to unit files to
conditionalize on certain firmware features. At the moment it may
check whether running on an UEFI system, a device.tree system, or if
the system is compatible with some specified device-tree feature.
* A new ConditionOSRelease= setting has been added to unit files to
check os-release(5) fields. The "=", "!=", "<", "<=", ">=", ">"
operators may be used to check if some field has some specific value
or do an alphanumerical comparison. Equality comparisons are useful
for fields like ID, but relative comparisons for fields like
VERSION_ID or IMAGE_VERSION.
* hostnamed gained a new Describe() D-Bus method that returns a JSON
serialization of the host data it exposes. This is exposed via
"hostnamectl --json=" to acquire a host identity description in JSON.
It's our intention to add a similar features to most services and
objects systemd manages, in order to simplify integration with
program code that can consume JSON.
* Similarly, networkd gained a Describe() method on its Manager and
Link bus objects. This is exposed via "networkctl --json=".
* hostnamectl's various "get-xyz"/"set-xyz" verb pairs
(e.g. "hostnamectl get-hostname", "hostnamectl "set-hostname") have
been replaced by a single "xyz" verb (e.g. "hostnamectl hostname")
that is used both to get the value (when no argument is given), and
to set the value (when an argument is specified). The old names
continue to be supported for compatibility.
* systemd-detect-virt and ConditionVirtualization= are now able to
correctly identify Amazon EC2 environments.
* The LogLevelMax= setting of unit files now applies not only to log
messages generated *by* the service, but also to log messages
generated *about* the service by PID 1. To suppress logs concerning a
specific service comprehensively, set this option to a high log
* bootctl gained support for a new --make-machine-id-directory= switch
that allows precise control on whether to create the top-level
per-machine directory in the boot partition that typically contains
Type 1 boot loader entries.
* During build SBAT data to include in the systemd-boot EFI PE binaries
may be specified now.
* /etc/crypttab learnt a new option "headless". If specified any
requests to query the user interactively for passwords or PINs will
be skipped. This is useful on systems that are headless, i.e. where
an interactive user is generally not present.
* /etc/crypttab also learnt a new option "password-echo=" that allows
configuring whether the encryption password prompt shall echo the
typed password and if so, do so literally or via asterisks. (The
default is the same behaviour as before: provide echo feedback via
* FIDO2 support in systemd-cryptenroll/systemd-cryptsetup and
systemd-homed has been updated to allow explicit configuration of the
"user presence" and "user verification" checks, as well as whether a
PIN is required for authentication, via the new switches
--fido2-with-client-pin= to systemd-cryptenroll and homectl. Which
features are available, and may be enabled or disabled depends on the
used FIDO2 token.
* systemd-nspawn's --private-user= switch now accepts the special value
"identity" which configures a user namespacing environment with an
identity mapping of 65535 UIDs. This means the container UID 0 is
mapped to the host UID 0, and the UID 1 to host UID 1. On first look
this doesn't appear to be useful, however it does reduce the attack
surface a bit, since the resulting container will possess process
capabilities only within its namespace and not on the host.
* systemd-nspawn's --private-user-chown switch has been replaced by a
more generic --private-user-ownership= switch that accepts one of
three values: "chown" is equivalent to the old --private-user-chown,
and "off" is equivalent to the absence of the old switch. The value
"map" uses the new UID mapping mounts of Linux 5.12 to map ownership
of files and directories of the underlying image to the chosen UID
range for the container. "auto" is equivalent to "map" if UID mapping
mount are supported, otherwise it is equivalent to "chown". The short
-U switch systemd-nspawn now implies --private-user-ownership=auto
instead of the old --private-user-chown. Effectively this means: if
the backing file system supports UID mapping mounts the feature is
now used by default if -U is used. Generally, it's a good idea to use
UID mapping mounts instead of recursive chown()ing, since it allows
running containers off immutable images (since no modifications of
the images need to take place), and share images between multiple
instances. Moreover, the recursive chown()ing operation is slow and
can be avoided. Conceptually it's also a good thing if transient UID
range uses do not leak into persistent file ownership anymore. TLDR:
finally, the last major drawback of user namespacing has been
removed, and -U should always be used (unless you use btrfs, where
UID mapped mounts do not exist; or your container actually needs
privileges on the host).
* nss-systemd now synthesizes user and group shadow records in addition
to the main user and group records. Thus, hashed passwords managed by
systemd-homed are now accessible via the shadow database.
* The userdb logic (and thus nss-systemd, and so on) now read
additional user/group definitions in JSON format from the drop-in
directories /etc/userdb/, /run/userdb/, /run/host/userdb/ and
/usr/lib/userdb/. This is a simple and powerful mechanism for making
additional users available to the system, with full integration into
NSS including the shadow databases. Since the full JSON user/group
record format is supported this may also be used to define users with
resource management settings and other runtime settings that
pam_systemd and systemd-logind enforce at login.
* The userdbctl tool gained two new switches --with-dropin= and
--with-varlink= which can be used to fine-tune the sources used for
user database lookups.
* systemd-nspawn gained a new switch --bind-user= for binding a host
user account into the container. This does three things: the user's
home directory is bind mounted from the host into the container,
below the /run/userdb/home/ hierarchy. A free UID is picked in the
container, and a user namespacing UID mapping to the host user's UID
installed. And finally, a minimal JSON user and group record (along
with its hashed password) is dropped into /run/host/userdb/. These
records are picked up automatically by the userdb drop-in logic
describe above, and allow the user to login with the same password as
on the host. Effectively this means: if host and container run new
enough systemd versions making a host user available to the container
is trivially simple.
* systemd-journal-gatewayd now supports the switches --user, --system,
--merge, --file= that are equivalent to the same switches of
journalctl, and permit exposing only the specified subset of the
* The OnFailure= dependency between units is now augmented with a
implicit reverse dependency OnFailureOf= (this new dependency cannot
be configured directly it's only created as effect of an OnFailure=
dependency in the reverse order — it's visible in "systemctl show"
however). Similar, Slice= now has an reverse dependency SliceOf=,
that is also not configurable directly, but useful to determine all
units that are members of a slice.
* A pair of new dependency types between units PropagatesStopTo= +
StopPropagatedFrom= has been added, that allows propagation of unit
stop events between two units. It operates similar to the existing
PropagatesReloadTo= + ReloadPropagatedFrom= dependencies.
* A new dependency type OnSuccess= has been added (plus the reverse
dependency OnSuccessOf=, which cannot be configured directly, but
exists only as effect of the reverse OnSuccess=). It is similar to
OnFailure=, but triggers in the opposite case: when a service exits
cleanly. This allows "chaining up" of services where one or more
services are started once another service has successfully completed.
* A new dependency type Upholds= has been added (plus the reverse
dependency UpheldBy=, which cannot be configured directly, but exists
only as effect of Upholds=). This dependency type is a stronger form
of Wants=: if a unit has an UpHolds= dependency on some other unit
and the former is active then the latter is started whenever it is
found inactive (and no job is queued for it). This is an alternative
to Restart= inside service units, but less configurable, and the
request to uphold a unit is not encoded in the unit itself but in
another unit that intends to uphold it.
* The systemd-ask-password tool now also supports reading passwords
from the credentials subsystem, via the new --credential= switch.
* The systemd-ask-password tool learnt a new switch --emoji= which may
be used to explicit control whether the lock and key emoji (🔐) is
shown in the password prompt on suitable TTYs.
* The --echo switch of systemd-ask-password now optionally takes a
parameter that controls character echo. It may either show asterisks
(default, as before), turn echo off entirely, or echo the typed
* The systemd-ask-password tool also gained a new -n switch for
suppressing output of a trailing newline character when writing the
acquired password to standard output, similar to /bin/echo's -n
* New documentation has been added that describes the organization of
the systemd source code tree:
* Units using ConditionNeedsUpdate= will no longer be activated in
* It is now possible to list a template unit in the WantedBy= or
RequiredBy= settings of the [Install] section of another template
unit, which will be instantiated using the same instance name.
* A new MemoryAvailable property is available for units. If the unit,
or the slice(s) it is part of, have a memory limit set via MemoryMax=/
MemoryHigh=, MemoryAvailable will indicate how much more memory the
unit can claim before hitting the limit(s).
* systemd-coredump will now try to stay below the cgroup memory limit
placed on itself or one of the slices it runs under, if the storage
area for core files (/var/lib/systemd/coredump/) is placed on a tmpfs,
since files written on such filesystems count toward the cgroup memory
limit. If there is not enough available memory in such cases to store
the core file uncompressed, systemd-coredump will skip to compressed
storage directly (if enabled) and it will avoid analyzing the core file
to print backtrace and metadata in the journal.
* tmpfiles.d/ drop-ins gained a new '=' modifier to check if the type
of a path matches the configured expectations, and remove it if not.
* tmpfiles.d/'s 'Age' now accepts an 'age-by' argument, which allows to
specify which of the several available filesystem timestamps (access
time, birth time, change time, modification time) to look at when
deciding whether a path has aged enough to be cleaned.
* A new IPv6StableSecretAddress= setting has been added to .network
files, which takes an IPv6 address to use as secret for IPv6 address
* The [DHCPServer] logic in .network files gained support for a new
UplinkInterface= setting that permits configuration of the uplink
interface name to propagate DHCP lease information from.
* The WakeOnLan= setting in .link files now accepts a list of flags
instead of a single one, to configure multiple wake-on-LAN policies.
* User-space defined tracepoints (USDT) have been added to udev at
strategic locations. This is useful for tracing udev behaviour and
performance with bpftrace and similar tools.
* systemd-journald-upload gained a new NetworkTimeoutSec= option for
setting a network timeout time.
* If a system service is running in a new mount namespace (RootDirectory=
and friends), all file systems will be mounted with MS_NOSUID by
default, unless the system is running with SELinux enabled.
* When enumerating time zones the timedatectl tool will now consult the
'tzdata.zi' file shipped by the IANA time zone database package, in
addition to 'zone1970.tab', as before. This makes sure time zone
aliases are now correctly supported. Some distributions so far did
not install this additional file, most do however. If you
distribution does not install it yet, it might make sense to change
Contributions from: Aakash Singh, adrian5, Albert Brox,
Alexander Sverdlin, Alexander Tsoy, Alexey Rubtsov, alexlzhu,
Allen Webb, Alvin Šipraga, Alyssa Ross, Anders Wenhaug,
Andrea Pappacoda, Anita Zhang, asavah, Balint Reczey, Bertrand Jacquin,
borna-blazevic, caoxia2008cxx, Carlo Teubner, Christian Göttsche,
Christian Hesse, Daniel Schaefer, Dan Streetman,
David Santamaría Rogado, David Tardon, Deepak Rawat, dgcampea,
Dimitri John Ledkov, ei-ke, Emilio Herrera, Emil Renner Berthing,
Eric Cook, Flos Lonicerae, Franck Bui, Francois Gervais,
Frantisek Sumsal, Gibeom Gwon, gitm0, Hamish Moffatt, Hans de Goede,
Harsh Barsaiyan, Henri Chain, Hristo Venev, Icenowy Zheng, Igor Zhbanov,
imayoda, Jakub Warczarek, James Buren, Jan Janssen, Jan Macku,
Jan Synacek, Jason Francis, Jayanth Ananthapadmanaban, Jeremy Szu,
Jérôme Carretero, Jesse Stricker, jiangchuangang, Joerg Behrmann,
Jóhann B. Guðmundsson, Jörg Deckert, Jörg Thalheim, Juergen Hoetzel,
Julia Kartseva, Kai-Heng Feng, Khem Raj, KoyamaSohei, laineantti,
Lennart Poettering, LetzteInstanz, Luca Adrian L, Luca Boccassi,
Lucas Magasweran, Mantas Mikulėnas, Marco Antonio Mauro, Mark Wielaard,
Masahiro Matsuya, Matt Johnston, Michael Catanzaro, Michal Koutný,
Michal Sekletár, Mike Crowe, Mike Kazantsev, Milan, milaq,
Miroslav Suchý, Morten Linderud, nerdopolis, nl6720, Noah Meyerhans,
Oleg Popov, Olle Lundberg, Ondrej Kozina, Paweł Marciniak, Perry.Yuan,
Peter Hutterer, Peter Kjellerstedt, Peter Morrow, Phaedrus Leeds,
plattrap, qhill, Raul Tambre, Roman Beranek, Roshan Shariff,
Ryan Hendrickson, Samuel BF, scootergrisen, Sebastian Blunt,
Seong-ho Cho, Sergey Bugaev, Sevan Janiyan, Sibo Dong, simmon,
Simon Watts, Srinidhi Kaushik, Štěpán Němec, Steve Bonds, Susant Sahani,
sverdlin, syyhao1994, Takashi Sakamoto, Topi Miettinen, tramsay,
Trent Piepho, Uwe Kleine-König, Viktor Mihajlovski, Vincent Dechenaux,
Vito Caputo, William A. Kennington III, Yangyang Shen, Yegor Alexeyev,
Yi Gao, Yu Watanabe, Zbigniew Jędrzejewski-Szmek, zsien, наб
— Edinburgh, 2021-07-07