Difference between revisions of "Systemd"

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[[Category:Daemons and system services]]
 
[[Category:Daemons and system services]]
 
[[Category:Boot process]]
 
[[Category:Boot process]]
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[[ar:Systemd]]
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[[es:Systemd]]
 
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[[fr:Systemd]]
 
[[fr:Systemd]]
 
[[it:Systemd]]
 
[[it:Systemd]]
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[[ja:Systemd]]
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[[pt:Systemd]]
 
[[ru:Systemd]]
 
[[ru:Systemd]]
 
[[zh-CN:Systemd]]
 
[[zh-CN:Systemd]]
{{Article summary start}}
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[[zh-TW:Systemd]]
{{Article summary text|Covers how to install and configure systemd.}}
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{{Related articles start}}
{{Article summary heading|Related}}
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{{Related|systemd/User}}
{{Article summary wiki|Systemd/Services}}
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{{Related|systemd/Timers}}
{{Article summary wiki|Init to systemd cheatsheet}}
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{{Related|systemd FAQ}}
{{Article summary wiki|udev}} - systemd and udev have been merged upstream.
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{{Related|init}}
{{Article summary end}}
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{{Related|init Rosetta}}
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{{Related|Daemons#List of daemons}}
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{{Related|udev}}
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{{Related|Improve boot performance}}
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{{Related|Allow users to shutdown}}
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{{Related articles end}}
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From the [http://freedesktop.org/wiki/Software/systemd project web page]:
 
From the [http://freedesktop.org/wiki/Software/systemd project web page]:
  
''"'''systemd''' is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides aggressive parallelization capabilities, uses socket and [[D-Bus]] activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux [[cgroups|control groups]], supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic. It can work as a drop-in replacement for sysvinit."''
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:''systemd'' is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides aggressive parallelization capabilities, uses socket and [[D-Bus]] activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux [[control groups]], supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic.
  
{{Note|For a detailed explanation as to why Arch is switching to systemd, see: [https://bbs.archlinux.org/viewtopic.php?pid=1149530#p1149530 this forum post].}}
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{{Note|1=For a detailed explanation as to why Arch has moved to ''systemd'', see [https://bbs.archlinux.org/viewtopic.php?pid=1149530#p1149530 this forum post].}}
  
See also the [[Wikipedia:Systemd|Wikipedia article]].
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== Basic systemctl usage  ==
  
== Things to consider before you switch ==
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The main command used to introspect and control ''systemd'' is ''systemctl''. Some of its uses are examining the system state and managing the system and services. See {{ic|man systemctl}} for more details.
  
* It is highly recommended to switch to the new '''initscripts''' configuration system described in the [[rc.conf|rc.conf article]].  Once you have this configuration established, you will have done most of the work needed to make the switch to systemd.
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{{Tip|
* Do [http://freedesktop.org/wiki/Software/systemd/ some reading] about systemd.
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* You can use all of the following ''systemctl'' commands with the {{ic|-H ''user''@''host''}} switch to control a ''systemd'' instance on a remote machine. This will use [[SSH]] to connect to the remote ''systemd'' instance.
* Note the fact that systemd has a '''journal''' system that replaces '''syslog''', although the two can co-exist. See the [[#Journald_in_conjunction_with_a_classic_syslog_daemon|section on the journal]] below.
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* ''systemadm'' is the official graphical frontend for ''systemctl'' and is provided by the {{Pkg|systemd-ui}} package.
* While systemd can replace some of the functionality of '''cron''', '''acpid''', or '''xinetd''', there is no need to switch away from using the traditional daemons unless you want to.
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* [[Plasma]] users can install {{Pkg|systemd-kcm}} as a graphical fronted for ''systemctl''. After installing the module will be added under ''System administration''.}}
  
== Installation ==
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=== Analyzing the system state ===
systemd can be installed side-by-side with the regular Arch Linux {{pkg|initscripts}} package, and they can be toggled by adding/removing the {{Ic|1=init=/bin/systemd}} [[kernel parameters|kernel parameter]].
+
  
=== A mixed systemd/sysvinit/initscripts installation ===
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Show '''system status''' using:
  
It is possible to keep systemd and sysvinit both installed and using the same configuration files so you can move back and forth between them freely:
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$ systemctl status
  
# Move away from the deprecated initscripts configuration formats (there should be warnings at boot) to the [[#Native systemd configuration files|native systemd configuration files]], and reboot to verify that this works as expected with initscripts.
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'''List running''' units:
# Install {{Pkg|systemd}} from the [[Official Repositories|official repositories]].
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# Add {{ic|1=init=/bin/systemd}} to the [[Kernel parameters|kernel parameters]] in your bootloader.
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# Reboot.
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Systemd will start the daemons listed in {{ic|/etc/rc.conf}} and run {{ic|/etc/rc.local}} and {{ic|/etc/rc.local.shutdown}} on boot/shutdown respectively.
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$ systemctl
  
=== A mixed systemd/initscripts installation ===
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or:
  
It is possible to replace sysvinit with systemd, but keep initscripts around in case there are some rc scripts which do not yet have systemd equivalents.
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$ systemctl list-units
  
# Follow the instructions for a mixed systemd/sysvinit/initscripts installation
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'''List failed''' units:
# [[#Using_Units|Enable daemons]] formerly listed in {{ic|/etc/rc.conf}} with {{ic|systemctl enable ''daemonname.'''service''' ''}}. For a translation of the daemons from {{ic|/etc/rc.conf}} to systemd services, see: [[Daemon#List_of_Daemons|List of Daemons]] and [[Systemd/Services|Services]]. Daemons that do not yet have equivalent systemd service files should be kept in the DAEMONS array so systemd will start the legacy rc scripts.
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# Install {{Pkg|systemd-sysvcompat}}. This conflicts with {{Pkg|sysvinit}}, and will prompt you to remove it.
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# Remove the {{ic|1=init=...}} entry as {{ic|/sbin/init}} is now a symlink to systemd.
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# Reboot.
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If the legacy support for DAEMONS in {{ic|rc.conf}} or the scripts in {{ic|rc.local}} is not needed, the corresponding service files can be masked to disable them.
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$ systemctl --failed
  
=== A pure systemd installation ===
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The available unit files can be seen in {{ic|/usr/lib/systemd/system/}} and {{ic|/etc/systemd/system/}} (the latter takes precedence). '''List installed''' unit files with:
  
Lastly, it is possible to remove initscripts and sysvinit entirely and only use systemd.
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$ systemctl list-unit-files
  
# Follow the instructions for a mixed systemd/initscripts installation
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=== Using units ===
# Make sure there are no longer any daemons being started by the DAEMONS array in {{ic|rc.conf and}} that {{ic|/etc/rc.local}} and {{ic|/etc/rc.local.shutdown}} are both empty.
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# Remove the initscripts package from your system.
+
  
=== Supplementary information ===
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Units can be, for example, services (''.service''), mount points (''.mount''), devices (''.device'') or sockets (''.socket'').
{{Note|1=In a pure systemd installation, installing {{pkg|systemd-sysvcompat}} replaces {{pkg|sysvinit}} and creates symlinks to halt, reboot, etc.}}
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{{Tip|If you have {{ic|quiet}} in your kernel parameters, you should remove it for your first couple of systemd boots, to assist with identifying any issues during boot.}}
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{{Warning|{{ic|/usr}} must be mounted and available at bootup (this is not particular to systemd). If your {{ic|/usr}} is on a separate partition, you will need to make accommodations to mount it from the initramfs and unmount it from a pivoted root on shutdown. See [[Mkinitcpio#/usr_as_a_separate_partition|the mkinitcpio wiki page]] and [http://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken freedesktop.org#separate-usr-is-broken].}}
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== Native systemd configuration files ==
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When using ''systemctl'', you generally have to specify the complete name of the unit file, including its suffix, for example {{ic|sshd.socket}}. There are however a few short forms when specifying the unit in the following ''systemctl'' commands:
{{Note|You may need to create these files.}}
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{{Pkg|systemd}} will use {{ic|/etc/rc.conf}} if these files are absent. Note this is temporary and not a long-term solution. It is strongly advised to use the systemd configuration files on any system.
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=== Hostname ===
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{{hc|/etc/hostname|myhostname}}
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=== Console and keymap ===
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* If you do not specify the suffix, systemctl will assume ''.service''. For example, {{ic|netctl}} and {{ic|netctl.service}} are equivalent.
The {{ic|/etc/vconsole.conf}} file configures the virtual console, i.e. keyboard mapping and console font.
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* Mount points will automatically be translated into the appropriate ''.mount'' unit. For example, specifying {{ic|/home}} is equivalent to {{ic|home.mount}}.
{{hc|/etc/vconsole.conf|<nowiki>
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* Similar to mount points, devices are automatically translated into the appropriate ''.device'' unit, therefore specifying {{ic|/dev/sda2}} is equivalent to {{ic|dev-sda2.device}}.
KEYMAP=us
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FONT=lat9w-16
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See {{ic|man systemd.unit}} for details.
FONT_MAP=8859-1_to_uni</nowiki>}}
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For more info see [[Fonts#Console_fonts|Console fonts]] and [[KEYMAP#Keyboard_layouts|Keymap]].
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{{Note|Some unit names contain an {{ic|@}} sign (e.g. {{ic|name@''string''.service}}): this means that they are [http://0pointer.de/blog/projects/instances.html instances] of a ''template'' unit, whose actual file name does not contain the {{ic|''string''}} part (e.g. {{ic|name@.service}}). {{ic|''string''}} is called the ''instance identifier'', and is similar to an argument that is passed to the template unit when called with the ''systemctl'' command: in the unit file it will substitute the {{ic|%i}} specifier.  
  
{{Tip|To use the kernel compiled-in font and keymap rather than the systemd-default ones use
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To be more accurate, ''before'' trying to instantiate the {{ic|name@.suffix}} template unit, ''systemd'' will actually look for a unit with the exact {{ic|name@string.suffix}} file name, although by convention such a "clash" happens rarely, i.e. most unit files containing an {{ic|@}} sign are meant to be templates. Also, if a template unit is called without an instance identifier, it will just fail, since the {{ic|%i}} specifier cannot be substituted.
{{hc|/etc/vconsole.conf|<nowiki>
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KEYMAP=
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FONT=
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</nowiki>}}
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This might be the default in the future.
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}}
 
}}
  
=== Locale ===
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{{Tip|
Read {{ic|man locale.conf}} for more options:
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* Most of the following commands also work if multiple units are specified, see {{ic|man systemctl}} for more information.
{{hc|/etc/locale.conf|<nowiki>
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* The {{ic|--now}} switch can be used in conjunction with {{ic|enable}}, {{ic|disable}}, and {{ic|mask}} to respectively start, stop, or mask immediately the unit rather than after the next boot.
LANG=en_US.UTF-8</nowiki>}}
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* A package may offer units for different purposes. If you just installed a package, {{ic|pacman -Qql ''package'' <nowiki>|</nowiki> grep -Fe .service -e .socket}} can be used to check and find them.}}
For more info see [[Locale]].
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=== Time zone ===
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'''Start''' a unit immediately:
Read {{ic|man 5 localtime}} for more options.
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# ln -sf /usr/share/zoneinfo/America/Chicago /etc/localtime
+
  
{{Note|{{ic|/etc/timezone}} has been deprecated in {{ic|systemd-190}} and can/should be deleted.}}
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# systemctl start ''unit''
  
=== Hardware clock time ===
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'''Stop''' a unit immediately:
Systemd will use UTC for the hardware clock by default and this is recommended. Dealing with daylight saving time is messy. If the DST changes when your computer is off, your clock will be wrong on next boot ([http://www.cl.cam.ac.uk/~mgk25/mswish/ut-rtc.html there is a lot more to it]). Recent kernels set the system time from the RTC directly on boot without using {{ic|hwclock}}, the kernel will always assume that the RTC is in UTC. This means that if the RTC is in local time, then the system time will first be set up wrongly and then corrected shortly afterwards on every boot. This is possibly the reason for certain weird bugs (time going backwards is rarely a good thing).
+
  
The reason for allowing the RTC to be in local time is to allow dual boot with Windows ([http://blogs.msdn.com/b/oldnewthing/archive/2004/09/02/224672.aspx which uses localtime]). Windows is able to deal with the RTC being in UTC with a simple [[Time#UTC_in_Windows|registry fix]]. If you run into issues on dual boot with Windows, you can set the hardware clock to local time.
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# systemctl stop ''unit''
  
{{hc|/etc/adjtime|
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'''Restart''' a unit:
0.0 0.0 0.0
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0
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LOCAL}}
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The other parameters are still needed but are ignored by systemd.
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# systemctl restart ''unit''
  
It is generally advised to have a [[NTP|Network Time Protocol daemon]] running to keep the hardware clock synchronized with the system time.
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Ask a unit to '''reload''' its configuration:
  
=== Kernel modules loaded during boot ===
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# systemctl reload ''unit''
systemd uses {{ic|/etc/modules-load.d/}} to configure kernel modules to load during boot in a static list. Each configuration file is named in the style of {{ic|/etc/modules-load.d/<program>.conf}}. The configuration files should simply contain a list of kernel module names to load, separated by newlines. Empty lines and lines whose first non-whitespace character is {{ic|#}} or {{ic|;}} are ignored. Example:
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{{hc|/etc/modules-load.d/virtio-net.conf|<nowiki>
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# Load virtio-net.ko at boot
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virtio-net</nowiki>}}
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See also [[Modprobe#Options]].
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=== Kernel modules blacklist ===
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Show the '''status''' of a unit, including whether it is running or not:
Module blacklisting works the same way as with {{Pkg|initscripts}} since it is actually handled by {{Pkg|kmod}}. See [[Kernel_modules#Blacklisting|Module Blacklisting]] for details.
+
  
=== Temporary files ===
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$ systemctl status ''unit''
Systemd-tmpfiles uses the configuration files in {{ic|/usr/lib/tmpfiles.d/}} and {{ic|/etc/tmpfiles.d/}} to describe the creation, cleaning and removal of volatile and temporary files and directories which usually reside in directories such as {{ic|/run}} or {{ic|/tmp}}. Each configuration file is named in the style of {{ic|/etc/tmpfiles.d/<program>.conf}}. This will also override any files in {{ic|/usr/lib/tmpfiles.d/}} with the same name.
+
  
tmpfiles are usually provided together with service files to create directories which are expected to exist by certain daemons. For example the [[Samba]] daemon expects the directory {{ic|/var/run/samba}} to exist and to have the correct permissions. The corresponding tmpfile looks like this:
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'''Check''' whether a unit is already enabled or not:
{{hc|/usr/lib/tmpfiles.d/samba.conf|
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D /var/run/samba 0755 root root
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}}
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However, tmpfiles may also be used to write values into certain files on boot. For example, if you use {{ic|/etc/rc.local}} to disable wakeup from USB devices with {{ic|echo USBE > /proc/acpi/wakeup}}, you may use the following tmpfile instead:
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$ systemctl is-enabled ''unit''
{{hc|/etc/tmpfiles.d/disable-usb-wake.conf|
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w /proc/acpi/wakeup - - - - USBE
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}}
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The tmpfiles method is recommended in this case since systemd doesn't actually support {{ic|/etc/rc.local}}.
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See {{ic|man tmpfiles.d}} for details.
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'''Enable''' a unit to be started on '''bootup''':
  
=== Remote filesystem mounts ===
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# systemctl enable ''unit''
systemd automatically makes sure that remote filesystem mounts like [[NFS]] or [[Samba]] are only started after the network has been set up. Therefore remote filesystem mounts specified in {{ic|/etc/fstab}} should work out of the box.
+
  
You may however want to use [[#Automount|Automount]] for remote filesystem mounts to mount them only upon access. Furthermore you can use the {{ic|1=x-systemd.device-timeout=#}} option in {{ic|/etc/fstab}} to specify a timeout in case the network resource is not available.
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'''Disable''' a unit to not start during bootup:
  
See {{ic|man systemd.mount}} for details.
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# systemctl disable ''unit''
  
=== ACPI Power Management with systemd ===
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'''Mask''' a unit to make it impossible to start it:
Systemd handles some power-related ACPI events. This is configured via the following options in {{ic|/etc/systemd/logind.conf}}:
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* {{ic|HandlePowerKey}}: specifies which action is invoked when the power key is pressed
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* {{ic|HandleSuspendKey}}: specifies which action is invoked when the suspend key is pressed
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* {{ic|HandleHibernateKey}}: specifies which action is invoked when the hibernate key is pressed
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* {{ic|HandleLidSwitch}}: specifies which action is invoked when the lid is closed
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The specified action can be one of {{ic|ignore}}, {{ic|poweroff}}, {{ic|reboot}}, {{ic|halt}}, {{ic|suspend}}, {{ic|hibernate}} or {{ic|kexec}}.
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If these options are not configured, systemd will use its defaults: {{ic|1=HandlePowerKey=poweroff}}, {{ic|1=HandleSuspendKey=suspend}}, {{ic|1=HandleHibernateKey=hibernate}}, and {{ic|1=HandleLidSwitch=suspend}}.
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# systemctl mask ''unit''
  
On systems which run no graphical setup or only a simple window manager like [[i3]] or [[awesome]], this may replace the [[acpid]] daemon which is usually used to react to these ACPI events.
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'''Unmask''' a unit:
  
In the current version of systemd, the {{ic|Handle}} options will apply throughout the system unless they are "inhibited" (temporarily turned off) by a program, such as a power manager inside a desktop environment. If these inhibits are not taken, you can end up with a situation where systemd suspends your system, then when it wakes up the other power manager suspends it again.
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# systemctl unmask ''unit''
  
{{Note|Currently, no power managers issue the necessary "inhibited" commands. Until they do, you will need to set the {{ic|Handle}} options to {{ic|ignore}} if you want your ACPI events to be handled by [[KDE]], [[GNOME]], [[Xfce]], [[acpid]] or any other program. New versions are on the way that will include this functionality.}}
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Show the '''manual page''' associated with a unit (this has to be supported by the unit file):
  
=== Sleep hooks ===
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$ systemctl help ''unit''
  
Systemd does not use [[pm-utils]] to put the machine to sleep when using {{ic|systemctl suspend}} or {{ic|systemctl hibernate}}, therefore [[pm-utils]] hooks including any [[Pm-utils#Creating_your_own_hooks|custom hooks]] created will not be run.  However, systemd provides a similar mechanism to run custom scripts on these events. Systemd runs all executables in {{ic|/usr/lib/systemd/system-sleep/}} and passes two arguments to each of them:
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Reload ''systemd'', scanning for '''new or changed units''':
  
* Argument 1: either {{ic|pre}} or {{ic|post}}, depending on whether the machine is going to sleep or waking up
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# systemctl daemon-reload
* Argument 2: either {{ic|suspend}} or {{ic|hibernate}}, depending on what has been invoked
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In contrast to [[pm-utils]], systemd will run these scripts in parallel and not one after another.
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=== Power management ===
  
The output of your script will be logged by {{ic|systemd-suspend.service}} or {{ic|systemd-hibernate.service}} so you can see its output in the [[Systemd#Systemd Journal|journal]].
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[[polkit]] is necessary for power management as an unprivileged user. If you are in a local ''systemd-logind'' user session and no other session is active, the following commands will work without root privileges. If not (for example, because another user is logged into a tty), ''systemd'' will automatically ask you for the root password.
  
Note that you can also use {{ic|sleep.target}}, {{ic|suspend.target}} or {{ic|hibernate.target}} to hook units into the sleep state logic instead of using scripts.
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Shut down and reboot the system:
  
See {{ic|man systemd.special}} and {{ic|man systemd-sleep}} for more information.
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$ systemctl reboot
  
==== Example ====
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Shut down and power-off the system:
{{hc|/usr/lib/systemd/system-sleep/example.sh|<nowiki>
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#!/bin/sh
+
  
case "$1" in
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$ systemctl poweroff
  pre )
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    echo going to $2 ...
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    ;;
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  post )
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    echo waking up from $2 ...
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    ;;
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esac</nowiki>}}
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=== Unit ===
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Suspend the system:
A unit configuration file encodes information about a service, a socket, a device, a mount point, an automount point, a swap file or partition, a start-up target, a file system path or a timer controlled and supervised by systemd. The syntax is inspired by XDG Desktop Entry Specification .desktop files, which are in turn inspired by Microsoft Windows .ini files. See {{ic|man systemd.unit}} for more info.
+
  
== Systemd commands ==
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$ systemctl suspend
  
*{{ic|systemctl}}: used to introspect and control the state of the systemd system and service manager.
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Put the system into hibernation:
*{{ic|systemd-cgls}}: recursively shows the contents of the selected Linux control group hierarchy in a tree
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*{{ic|systemadm}}: a graphical frontend for the systemd system and service manager that allows introspection and control of systemd (available via the {{AUR|systemd-ui-git}} package from the [[AUR]]).
+
  
View the man pages for more details.
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$ systemctl hibernate
  
{{Tip|You can use all of the following {{ic|systemctl}} commands with the {{ic|-H <user>@<host>}} switch to control a systemd instance on a remote machine. This will use [[SSH]] to connect to the remote systemd instance.}}
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Put the system into hybrid-sleep state (or suspend-to-both):
  
=== Analyzing the system state ===
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$ systemctl hybrid-sleep
  
List running units:
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== Writing unit files ==
  
{{bc|$ systemctl}}
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The syntax of ''systemd'''s [http://www.freedesktop.org/software/systemd/man/systemd.unit.html unit files] is inspired by XDG Desktop Entry Specification ''.desktop'' files, which are in turn inspired by Microsoft Windows ''.ini'' files. Unit files are loaded from two locations. From lowest to highest precedence they are:
  
or:
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* {{ic|/usr/lib/systemd/system/}}: units provided by installed packages
 +
* {{ic|/etc/systemd/system/}}: units installed by the system administrator
  
{{bc|$ systemctl list-units}}
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{{Note|
 +
* The load paths are completely different when running ''systemd'' in [[systemd/User#How it works|user mode]].
 +
* systemd unit names may only contain ASCII alphanumeric characters, underscores and periods. All other characters must be replaced by C-style "\x2d" escapes. See {{ic|man systemd.unit}} and {{ic|man systemd-escape}} for more information.}}
  
List failed units:
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Look at the units installed by your packages for examples, as well as the [http://www.freedesktop.org/software/systemd/man/systemd.service.html#Examples annotated example section] of {{ic|man systemd.service}}.
  
{{bc|$ systemctl --failed}}
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{{Tip|Comments prepended with {{ic|#}} may be used in unit-files as well, but only in new lines. Do not use end-line comments after ''systemd'' parameters or the unit will fail to activate.}}
  
The available unit files can be seen in {{ic|/usr/lib/systemd/system/}} and {{ic|/etc/systemd/system/}} (the latter takes precedence). You can see list installed unit files by:
+
=== Handling dependencies ===
{{bc|$ systemctl list-unit-files}}
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=== Using Units ===
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With ''systemd'', dependencies can be resolved by designing the unit files correctly. The most typical case is that the unit ''A'' requires the unit ''B'' to be running before ''A'' is started. In that case add {{ic|1=Requires=''B''}} and {{ic|1=After=''B''}} to the {{ic|[Unit]}} section of ''A''. If the dependency is optional, add {{ic|1=Wants=''B''}} and {{ic|1=After=''B''}} instead. Note that {{ic|1=Wants=}} and {{ic|1=Requires=}} do not imply {{ic|1=After=}}, meaning that if {{ic|1=After=}} is not specified, the two units will be started in parallel.
  
Units can be, for example, services ({{ic|.service}}), mount points ({{ic|.mount}}), devices ({{ic|.device}}) or sockets ({{ic|.socket}}).
+
Dependencies are typically placed on services and not on targets. For example, {{ic|network.target}} is pulled in by whatever service configures your network interfaces, therefore ordering your custom unit after it is sufficient since {{ic|network.target}} is started anyway.
When using {{ic|systemctl}}, you generally have to specify the complete name of the unit file, including its suffix, for example {{ic|sshd.socket}}. There are however a few shortforms when specifying the unit in the following {{ic|systemctl}} commands:
+
* If you don't specify the suffix, systemctl will assume {{ic|.service}}. For example, {{ic|netcfg}} and {{ic|netcfg.service}} are treated equivalent. {{Note|This currently does not work with the commands {{ic|enable}} and {{ic|disable}}.}}
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* Mount points will automatically be translated into the appropriate {{ic|.mount}} unit. For example, specifying {{ic|/home}} is equivalent to {{ic|home.mount}}.
+
* Similiar to mount points, devices are automatically translated into the appropriate {{ic|.device}} unit, therefore specifying {{ic|/dev/sda2}} is equivalent to {{ic|dev-sda2.device}}.
+
  
See {{ic|man systemd.unit}} for details.
+
=== Service types ===
  
Activate a unit immediately:
+
There are several different start-up types to consider when writing a custom service file. This is set with the {{ic|1=Type=}} parameter in the {{ic|[Service]}} section:
  
{{bc|# systemctl start <unit>}}
+
* {{ic|1=Type=simple}} (default): ''systemd'' considers the service to be started up immediately. The process must not fork. Do not use this type if other services need to be ordered on this service, unless it is socket activated.
 +
* {{ic|1=Type=forking}}: ''systemd'' considers the service started up once the process forks and the parent has exited. For classic daemons use this type unless you know that it is not necessary. You should specify {{ic|1=PIDFile=}} as well so ''systemd'' can keep track of the main process.
 +
* {{ic|1=Type=oneshot}}: this is useful for scripts that do a single job and then exit. You may want to set {{ic|1=RemainAfterExit=yes}} as well so that ''systemd'' still considers the service as active after the process has exited.
 +
* {{ic|1=Type=notify}}: identical to {{ic|1=Type=simple}}, but with the stipulation that the daemon will send a signal to ''systemd'' when it is ready. The reference implementation for this notification is provided by ''libsystemd-daemon.so''.
 +
* {{ic|1=Type=dbus}}: the service is considered ready when the specified {{ic|BusName}} appears on DBus's system bus.
 +
* {{ic|1=Type=idle}}: ''systemd'' will delay execution of the service binary until all jobs are dispatched. Other than that behavior is very similar to {{ic|1=Type=simple}}.
  
Deactivate a unit immediately:
+
See the [http://www.freedesktop.org/software/systemd/man/systemd.service.html#Type= systemd.service(5)] man page for a more detailed explanation of the {{ic|Type}} values.
  
{{bc|# systemctl stop <unit>}}
+
=== Editing provided units ===
  
Restart a unit:
+
To avoid conflicts with pacman, unit files provided by packages should not be directly edited. There are two safe ways to modify a unit without touching the original file: create a new unit file which overwrites the original unit or create drop-in snippets which are applied on top of the original unit. For both methods, you must reload the unit afterwards to apply your changes. This can be done either by editing the unit with {{ic|systemctl edit}} (which reloads the unit automatically) or by reloading all units with:
  
{{bc|# systemctl restart <unit>}}
+
# systemctl daemon-reload
  
Ask a unit to reload its configuration:
+
{{Tip|
 +
* You can use ''systemd-delta'' to see which unit files have been overridden or extended and what exactly has been changed.
 +
* Use {{ic|systemctl cat ''unit''}} to view the content of a unit file and all associated drop-in snippets.
 +
* Syntax highlighting for ''systemd'' unit files within [[Vim]] can be enabled by installing {{Pkg|vim-systemd}}.
 +
}}
  
{{bc|# systemctl reload <unit>}}
+
==== Replacement unit files ====
  
Show the status of a unit, including whether it is running or not:
+
To replace the unit file {{ic|/usr/lib/systemd/system/''unit''}}, create the file {{ic|/etc/systemd/system/''unit''}} and reenable the unit to update the symlinks:
  
{{bc|$ systemctl status <unit>}}
+
# systemctl reenable ''unit''
  
Check whether a unit is already enabled or not:
+
Alternatively, run:
  
{{bc|$ systemctl is-enabled <unit>}}
+
# systemctl edit --full ''unit''
  
Enable a unit to be started on bootup:
+
This opens {{ic|/etc/systemd/system/''unit''}} in your editor (copying the installed version if it does not exist yet) and automatically reloads it when you finish editing.
  
{{bc|# systemctl enable <unit>}}
+
{{Note|Pacman does not update the replacement unit files when the originals are updated, so this method can make system maintenance more difficult. For this reason the next approach is recommended.}}
  
{{Note| If services do not have an Install section, it usually means they are called automatically by other services.  But if you need to install them manually, use the following command, replacing ''foo'' with the name of the service.
+
==== Drop-in files ====
  
{{bc|# ln -s /usr/lib/systemd/system/''foo''.service /etc/systemd/system/graphical.target.wants/}}
+
To create drop-in files for the unit file {{ic|/usr/lib/systemd/system/''unit''}}, create the directory {{ic|/etc/systemd/system/''unit''.d/}} and place ''.conf'' files there to override or add new options. ''systemd'' will parse these ''.conf'' files and apply them on top of the original unit.
  
}}
+
The easiest way to do this is to run:
  
Disable a unit to not start during bootup:
+
# systemctl edit ''unit''
  
{{bc|# systemctl disable <unit>}}
+
This opens the file {{ic|/etc/systemd/system/''unit''.d/override.conf}} in your text editor (creating it if necessary) and automatically reloads the unit when you are done editing.
  
Show the manual page associated with a unit (this has to be supported by the unit file):
+
==== Examples ====
  
{{bc|$ systemctl help <unit>}}
+
For example, if you simply want to add an additional dependency to a unit, you may create the following file:
  
=== Power Management ===
+
{{hc|/etc/systemd/system/''unit''.d/customdependency.conf|2=
 +
[Unit]
 +
Requires=''new dependency''
 +
After=''new dependency''
 +
}}
  
If you are in a local {{ic|systemd-logind}} or [[ConsoleKit]] user session and no other session is active, the following commands will work without root privileges. If not (for example, because another user is logged into a tty), systemd will automatically ask you for the root password (see also [[#Replacing_ConsoleKit_with_systemd-logind|Replacing ConsoleKit with systemd-logind]]).
+
As another example, in order to replace the {{ic|ExecStart}} directive for a unit that is not of type {{ic|oneshot}}, create the following file:
  
Shut down and reboot the system:
+
{{hc|/etc/systemd/system/''unit''.d/customexec.conf|2=
 +
[Service]
 +
ExecStart=
 +
ExecStart=''new command''
 +
}}
  
{{bc|$ systemctl reboot}}
+
Note how {{ic|ExecStart}} must be cleared before being re-assigned ([https://bugzilla.redhat.com/show_bug.cgi?id=756787#c9]). The same holds for every item that can be specified multiple times, e.g. {{ic|OnCalendar}} for timers.
  
Shut down and power-off the system:
+
One more example to automatically restart a service:
  
{{bc|$ systemctl poweroff}}
+
{{hc|/etc/systemd/system/''unit''.d/restart.conf|2=
 +
[Service]
 +
Restart=always
 +
RestartSec=30
 +
}}
  
Shut down and halt the system:
+
== Targets ==
  
{{bc|$ systemctl halt}}
+
{{Style|Unclear description, copy-pasted content (explicitly mentions "Fedora").|section=Make section "Targets" more clearly}}
  
Suspend the system:
+
''systemd'' uses ''targets'' which serve a similar purpose as runlevels but act a little different. Each ''target'' is named instead of numbered and is intended to serve a specific purpose with the possibility of having multiple ones active at the same time. Some ''target''s are implemented by inheriting all of the services of another ''target'' and adding additional services to it. There are ''systemd'' ''target''s that mimic the common SystemVinit runlevels so you can still switch ''target''s using the familiar {{ic|telinit RUNLEVEL}} command.
  
{{bc|$ systemctl suspend}}
+
=== Get current targets ===
  
Hibernate the system:
+
The following should be used under ''systemd'' instead of running {{ic|runlevel}}:
  
{{bc|$ systemctl hibernate}}
+
$ systemctl list-units --type=target
 
+
== Runlevels/targets ==
+
Runlevels is a legacy concept in systemd. Systemd uses ''targets'' which serve a similar purpose as runlevels but act a little different. Each ''target'' is named instead of numbered and is intended to serve a specific purpose with the possibility of having multiple ones active at the same time. Some ''targets'' are implemented by inheriting all of the services of another ''target'' and adding additional services to it. There are systemd ''target''s that mimic the common SystemVinit runlevels so you can still switch ''target''s using the familiar {{ic|telinit RUNLEVEL}} command.
+
 
+
=== Get current runlevel/targets ===
+
The following should be used under systemd instead of {{ic|runlevel}}:
+
{{bc|1=# systemctl list-units --type=target}}
+
  
 
=== Create custom target ===
 
=== Create custom target ===
The runlevels that are assigned a specific purpose on vanilla Fedora installs; 0, 1, 3, 5, and 6; have a 1:1 mapping with a specific systemd ''target''. Unfortunately, there is no good way to do the same for the user-defined runlevels like 2 and 4. If you make use of those it is suggested that you make a new named systemd ''target'' as {{ic|/etc/systemd/system/<your target>}} that takes one of the existing runlevels as a base (you can look at {{ic|/usr/lib/systemd/system/graphical.target}} as an example), make a directory {{ic|/etc/systemd/system/<your target>.wants}}, and then symlink the additional services from {{ic|/usr/lib/systemd/system/}} that you wish to enable.
+
 
 +
The runlevels that held a defined meaning under sysvinit (i.e., 0, 1, 3, 5, and 6); have a 1:1 mapping with a specific ''systemd'' ''target''. Unfortunately, there is no good way to do the same for the user-defined runlevels like 2 and 4. If you make use of those it is suggested that you make a new named ''systemd'' ''target'' as {{ic|/etc/systemd/system/''your target''}} that takes one of the existing runlevels as a base (you can look at {{ic|/usr/lib/systemd/system/graphical.target}} as an example), make a directory {{ic|/etc/systemd/system/''your target''.wants}}, and then symlink the additional services from {{ic|/usr/lib/systemd/system/}} that you wish to enable.
  
 
=== Targets table ===
 
=== Targets table ===
{| border="1"
+
 
!SysV Runlevel!!Systemd Target!!Notes
+
{| class="wikitable"
 +
! SysV Runlevel !! systemd Target !! Notes
 
|-
 
|-
 
| 0 || runlevel0.target, poweroff.target || Halt the system.
 
| 0 || runlevel0.target, poweroff.target || Halt the system.
Line 330: Line 292:
 
|}
 
|}
  
=== Change current runlevels ===
+
=== Change current target ===
In systemd runlevels are exposed via "target units". You can change them like this:
+
{{bc|# systemctl isolate graphical.target}}
+
This will only change the current runlevel, and has no effect on the next boot. This is equivalent to commands such as {{ic|telinit 3}} or {{ic|telinit 5}} in Sysvinit.
+
  
=== Change default runlevel/target to boot into ===
+
In ''systemd'' targets are exposed via ''target units''. You can change them like this:
The standard target is {{ic|default.target}}, which is aliased by default to {{ic|graphical.target}} (which roughly corresponds to the old runlevel 5). To change the default target at boot-time, append one of the following kernel parameters to your bootloader:
+
* {{ic|1=systemd.unit=multi-user.target}} (which roughly corresponds to the old runlevel 3),
+
* {{ic|1=systemd.unit=rescue.target}} (which roughly corresponds to the old runlevel 1).
+
  
Alternatively, you may leave the bootloader alone and change {{ic|default.target}}. This can be done using {{ic|systemctl}}:
+
# systemctl isolate graphical.target
{{bc|# systemctl enable multi-user.target}}
+
  
The effect of this command is outputted by {{ic|systemctl}}; a symlink to the new default target is made at {{ic|/etc/systemd/system/default.target}}. This works if, and only if:
+
This will only change the current target, and has no effect on the next boot. This is equivalent to commands such as {{ic|telinit 3}} or {{ic|telinit 5}} in Sysvinit.
[Install]
+
Alias=default.target
+
is in the target's configuration file. Currently, {{ic|multi-user.target}} and {{ic|graphical.target}} both have it.
+
  
== Running DEs under systemd ==
+
=== Change default target to boot into ===
  
=== Using display manager ===
+
The standard target is {{ic|default.target}}, which is aliased by default to {{ic|graphical.target}} (which roughly corresponds to the old runlevel 5). To change the default target at boot-time, append one of the following [[kernel parameters]] to your bootloader:
To enable graphical login, run your preferred [[Display Manager]] daemon (e.g. [[KDM]]). At the moment, service files exist for [[GDM]], [[KDM]], [[SLiM]], [[XDM]], [[LXDM]] and [[LightDM]].
+
  
{{bc|# systemctl enable kdm.service}}
+
* {{ic|1=systemd.unit=multi-user.target}} (which roughly corresponds to the old runlevel 3),
 +
* {{ic|1=systemd.unit=rescue.target}} (which roughly corresponds to the old runlevel 1).
  
This should work out of the box. If not, you might have a {{ic|default.target}} set manually or from a older install:
+
Alternatively, you may leave the bootloader alone and change {{ic|default.target}}. This can be done using ''systemctl'':
  
{{hc|# ls -l /etc/systemd/system/default.target|/etc/systemd/system/default.target -> /usr/lib/systemd/system/graphical.target}}
+
# systemctl set-default multi-user.target
  
Simply delete the symlink and systemd will use its stock {{ic|default.target}} (i.e. {{ic|graphical.target}}).
+
To be able to override the previously set {{ic|default.target}}, use the force option:
  
{{bc|# rm /etc/systemd/system/default.target}}
+
# systemctl set-default -f multi-user.target
  
=== Using service file ===
+
The effect of this command is output by ''systemctl''; a symlink to the new default target is made at {{ic|/etc/systemd/system/default.target}}.
{{Note|Using this method there will be no PAM session created for your user. Therefore ConsoleKit (which gives you access to shutdown/reboot, audio devices etc.) will not work properly. For the recommended way, see: [[#Replacing_ConsoleKit_with_systemd-logind|Replacing ConsoleKit with systemd-logind]] and [[Automatic_login_to_virtual_console#With_systemd]].}}
+
If you are only looking for a simple way to start X directly without a display manager, you can create a service file similar to this:
+
  
{{hc|/etc/systemd/system/graphical.target.wants/xinit.service|<nowiki>
+
== Temporary files ==
[Unit]
+
Description=Direct login to X
+
After=systemd-user-sessions.service
+
  
[Service]
+
"''systemd-tmpfiles'' creates, deletes and cleans up volatile and temporary files and directories." It reads configuration files in {{ic|/etc/tmpfiles.d/}} and {{ic|/usr/lib/tmpfiles.d/}} to discover which actions to perform. Configuration files in the former directory take precedence over those in the latter directory.
ExecStart=/bin/su <username> -l -c "/bin/bash --login -c xinit"
+
  
[Install]
+
Configuration files are usually provided together with service files, and they are named in the style of {{ic|/usr/lib/tmpfiles.d/''program''.conf}}. For example, the [[Samba]] daemon expects the directory {{ic|/run/samba}} to exist and to have the correct permissions. Therefore, the {{Pkg|samba}} package ships with this configuration:
WantedBy=graphical.target
+
</nowiki>}}
+
  
== Systemd Journal ==
+
{{hc|/usr/lib/tmpfiles.d/samba.conf|
Since version 38 systemd has an own logging system, the journal.
+
D /run/samba 0755 root root}}
  
By default, running a syslog daemon is no longer required. To read the log, use:
+
Configuration files may also be used to write values into certain files on boot. For example, if you used {{ic|/etc/rc.local}} to disable wakeup from USB devices with {{ic|echo USBE > /proc/acpi/wakeup}}, you may use the following tmpfile instead:
{{bc|# journalctl}}
+
The journal writes to {{ic|/run/systemd/journal}}, meaning logs will be lost on reboot. For non-volatile logs, create {{ic|/var/log/journal/}}:
+
{{bc|# mkdir /var/log/journal/}}
+
  
=== Filtering output ===
+
{{hc|/etc/tmpfiles.d/disable-usb-wake.conf|
 +
w /proc/acpi/wakeup - - - - USBE}}
  
{{ic|journalctl}} allows you to filter the output by specific fields.
+
See the {{ic|systemd-tmpfiles(8)}} and {{ic|tmpfiles.d(5)}} man pages for details.
  
Examples:
+
{{Note|This method may not work to set options in {{ic|/sys}} since the ''systemd-tmpfiles-setup'' service may run before the appropriate device modules is loaded. In this case you could check whether the module has a parameter for the option you want to set with {{ic|modinfo ''module''}} and set this option with a [[Kernel modules#Setting module options|config file in /etc/modprobe.d]]. Otherwise you will have to write a [[Udev#About_udev_rules|udev rule]] to set the appropriate attribute as soon as the device appears.}}
  
Show all messages by a specific executable:
+
== Timers ==
{{bc|# journalctl /usr/lib/systemd/systemd}}
+
  
Show all messages by a specific process:
+
A timer is a unit configuration file whose name ends with ''.timer'' and encodes information about a timer controlled and supervised by ''systemd'', for timer-based activation. See [[systemd/Timers]].
{{bc|1=# journalctl _PID=1}}
+
  
Show all messages by a specific unit:
+
{{Note|Timers can replace ''cron'' functionality to a great extent. See [[systemd/Timers#As a cron replacement]].}}
{{bc|1=# journalctl _SYSTEMD_UNIT=netcfg.service}}
+
  
See {{ic|man journalctl}} and {{ic|systemd.journal-fields}} for details.
+
== Mounting ==
  
=== Journal size limit ===
+
Since systemd is a replacement for System V init, it is in charge of the mounts specified in {{ic|/etc/fstab}}. In fact, it goes beyond the usual {{ic|fstab}} capabilities, implementing special mount options prefixed with {{ic|x-systemd.}}. See [[Fstab#Automount with systemd]] for an example of ''automounting'' (mounting on-demand) using these extensions. See [https://www.freedesktop.org/software/systemd/man/systemd.mount.html#fstab] for the complete documentation of these extensions.
  
If the journal is made non-volatile, its size limit is set to a default value of 10% of the size of the respective file system. E.g. with {{ic|/var/log/journal}} located on a 50 GiB root partition this would lead to 5 GiB of journal data. The maximum size of the persistent journal can be controlled by {{ic|SystemMaxUse}} in {{ic|/etc/systemd/journald.conf}}, so to limit it for example to 50 MiB uncomment and edit the corresponding line to:
+
== Journal ==
{{bc|1=SystemMaxUse=50M}}
+
Refer to {{ic|man journald.conf}} for more info.
+
  
===Journald in conjunction with a classic syslog daemon===
+
''systemd'' has its own logging system called the journal; therefore, running a {{ic|syslog}} daemon is no longer required. To read the log, use:
Compatibility with classic syslog implementations is provided via a
+
socket {{ic|/run/systemd/journal/syslog}}, to which all messages are forwarded.
+
To make the syslog daemon work with the journal, it has to bind to this socket instead of {{ic|/dev/log}} ([http://lwn.net/Articles/474968/ official announcement]). For syslog-ng, change the {{ic|source src}} section in {{ic|/etc/syslog-ng/syslog-ng.conf}} to:
+
{{bc|<nowiki>
+
source src {
+
    unix-dgram("/run/systemd/journal/syslog");
+
    internal();
+
    file("/proc/kmsg");
+
};</nowiki>}}
+
  
and enable syslog-ng:
+
# journalctl
{{bc|# systemctl enable syslog-ng.service}}
+
  
== Network ==
+
In Arch Linux, the directory {{ic|/var/log/journal/}} is a part of the {{Pkg|systemd}} package, and the journal (when {{ic|1=Storage=}} is set to {{ic|auto}} in {{ic|/etc/systemd/journald.conf}}) will write to {{ic|/var/log/journal/}}. If you or some program delete that directory, ''systemd'' will '''not''' recreate it automatically and instead will write its logs to {{ic|/run/systemd/journal}} in a nonpersistent way. However, the folder will be recreated when you set {{ic|1=Storage=persistent}} and run {{ic|systemctl restart systemd-journald}} (or reboot).
=== Dynamic (DHCP) with dhcpcd ===
+
If you simply want to use DHCP for your Ethernet connection, you can use {{ic|dhcpcd@.service}} (provided by the {{Pkg|dhcpcd}} package).
+
To enable DHCP for {{ic|eth0}}, simply use:
+
# systemctl start dhcpcd@eth0.service
+
  
You can enable the service to automatically start at boot with:
+
The systemd journal event notification message logging classification corresponds to classical BSD syslog protocol style ([[wikipedia:Syslog|Wikipedia]], [https://tools.ietf.org/html/rfc5424 RFC 5424]). For more info see subsections [[#Facility|Facility]], [[#Priority level|Priority level]], and for examples on how to use it in [[#Filtering output|Filtering output]].
# systemctl enable dhcpcd@eth0.service
+
  
Sometimes the dhcpd service starts before your network card module ({{bug|30235}}), manually add your network card to {{ic|/etc/modules-load.d/****.conf}}. Example: create {{ic|/etc/modules-load.d/r8169.conf}}, this is a realtek card
+
===Facility===
# r8169
+
  
=== Other configurations ===
+
A syslog facility code is used to specify the type of program that is logging the message [https://tools.ietf.org/html/rfc5424#section-6.2.1 RFC 5424 Section 6.2.1].
For static, wireless or advanced network configuration like bridging you can use [[Netcfg#systemd_support|netcfg]] or [[NetworkManager#Enable_NetworkManager_under_Native_systemd_system|NetworkManager]] which both provide systemd service files.
+
{{Note|If you want to use netcfg, networkmanager or another software for managing the network you don't need to start/enable dhcpcd as seen on the previous paragraph.}}
+
  
If you need a static Ethernet configuration, but don't want to use [[netcfg]], there is a custom service file available on the [[Systemd/Services#Static_Ethernet_network|Systemd/Services page]].
+
{| class="wikitable"
 +
! Facility code !! Keyword !! Description !! Info
 +
|-
 +
| 0 || kern || kernel messages
 +
|-
 +
| 1 || user || user-level messages
 +
|-
 +
| 2 || mail || mail system || Archaic POSIX still supported and sometimes used system, for more {{ic|man mail}})
 +
|-
 +
| 3 || daemon || system daemons || All deamons, including systemd and its subsystems
 +
|-
 +
| 4 || auth || security/authorization messages || Also watch for different facility 10
 +
|-
 +
| 5 || syslog || messages generated internally by syslogd || As it standartized for syslogd, not used by systemd (see facility 3)
 +
|-
 +
| 6 || lpr || line printer subsystem (archaic subsystem)
 +
|-
 +
| 7 || news || network news subsystem (archaic subsystem)
 +
|-
 +
| 8 || uucp || UUCP subsystem (archaic subsystem)
 +
|-
 +
| 9 || || clock daemon || systemd-timesyncd
 +
|-
 +
| 10 || authpriv || security/authorization messages || Also watch for different facility 4
 +
|-
 +
| 11 || ftp || FTP daemon
 +
|-
 +
| 12 || - || NTP subsystem
 +
|-
 +
| 13 || - || log audit
 +
|-
 +
| 14 || - || log alert
 +
|-
 +
| 15 || cron || scheduling daemon
 +
|-
 +
| 16 || local0 || local use 0  (local0)
 +
|-
 +
| 17 || local1 || local use 1  (local1)
 +
|-
 +
| 18 || local2 || local use 2  (local2)
 +
|-
 +
| 19 || local3 || local use 3  (local3)
 +
|-
 +
| 20 || local4 || local use 4  (local4)
 +
|-
 +
| 21 || local5 || local use 5  (local5)
 +
|-
 +
| 22 || local6 || local use 6  (local6)
 +
|-
 +
| 23 || local7 || local use 7  (local7)
 +
|}
  
== Arch integration ==
+
So, useful facilities to watch: 0,1,3,4,9,10,15.
=== Initscripts emulation ===
+
Integration with Arch's classic configuration is provided by the {{Pkg|initscripts}} package. This is simply meant as a transitional measure to ease users' move to systemd.
+
  
{{Note|{{ic|/etc/inittab}} is not used at all.}}
+
===Priority level===
  
If you disabled {{keypress|Ctrl+Alt+Del}} to reboot in {{ic|/etc/inittab}}, you will have to reconfigure this setting for systemd by running {{ic|systemctl mask ctrl-alt-del.target}} as root.
+
A syslog severity code (in systemd called priority) is used to mark the importance of a message [https://tools.ietf.org/html/rfc5424#section-6.2.1 RFC 5424 Section 6.2.1].
  
==== rc.conf ====
 
Some variables in {{ic|/etc/rc.conf}} are respected by this glue work. For a pure systemd setup, it is recommended to use the [[Systemd#Native_systemd_configuration_files|native systemd configuration files]] which will take precedence over {{ic|/etc/rc.conf}}.
 
 
Supported variables:
 
* {{ic|LOCALE}}
 
* {{ic|KEYMAP}}
 
* {{ic|CONSOLEFONT}}
 
* {{ic|CONSOLEMAP}}
 
* {{ic|HOSTNAME}}
 
* {{ic|DAEMONS}}
 
 
Not supported variables and systemd configuration:
 
* {{ic|TIMEZONE}}: Please symlink {{Ic|/etc/localtime}} to your zoneinfo file manually.
 
* {{ic|HARDWARECLOCK}}: See [[Systemd#Hardware clock time|Hardware clock time]].
 
* {{ic|USELVM}}: use {{ic|lvm.service}} provided by {{Pkg|lvm2}} instead.
 
* {{ic|USECOLOR}}
 
* {{ic|MODULES}}
 
 
=== Total conversion to native systemd ===
 
{{Note|This is the preferred method, where the system does not rely on {{ic|rc.conf}} centralised configuration anymore, but uses native systemd configuration files.}}
 
 
Follow system configuration as explained in [[#Native_systemd_configuration_files]]. Each file replaces one section of {{ic|/etc/rc.conf}} as shown in that table:
 
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
! scope="col"| Configuration
+
! Value !! Severity !! Keyword  !! Description || Examples
! scope="col"| Configuration file(s)
+
! scope="col"| Legacy {{ic|/etc/rc.conf}} section
+
 
|-
 
|-
| align="center"|Hostname
+
| 0 || Emergency || emerg || System is unusable || Severe Kernel BUG, systemd dumped core.<br>This level should not be used by applications.
| align="left"|{{ic|/etc/hostname}}
+
{{ic|/etc/hosts}}
+
| align="center"|{{ic|NETWORKING}}
+
 
|-
 
|-
| align="center"|Console fonts and Keymap
+
| 1 || Alert || alert || Should be corrected immediately || Vital subsystem goes out of work. Data loss. <br>{{ic|kernel: BUG: unable to handle kernel paging request at ffffc90403238ffc|}}.
| align="left"|{{ic|/etc/vconsole.conf}}
+
| align="center"|{{ic|LOCALIZATION}}
+
 
|-
 
|-
| align="center"|Locale
+
| 2 || Critical || crit || Critical conditions || Crashes, coredumps. Like familiar flash:<br>{{ic|systemd-coredump[25319]: Process 25310 (plugin-containe) of user 1000 dumped core}}<br>Failure in the system primary application, like X11.
| align="left"|{{ic|/etc/locale.conf}}
+
{{ic|/etc/locale.gen}}
+
| align="center"|{{ic|LOCALIZATION}}
+
 
|-
 
|-
| align="center"|Time zone
+
| 3 || Error || err || Error conditions || Not severe error reported:<br>{{ic|kernel: usb 1-3: 3:1: cannot get freq at ep 0x84}},<br>{{ic|systemd[1]: Failed unmounting /var.}},<br>{{ic|libvirtd[1720]: internal error: Failed to initialize a valid firewall backend}}).
| align="left"|{{ic|/etc/localtime}}
+
| align="center"|{{ic|LOCALIZATION}}
+
 
|-
 
|-
| align="center"|Hardware clock
+
| 4 || Warning || warning || May indicate that an error will occur if action is not taken. || A non-root file system has only 1GB free.<br>{{ic|org.freedesktop. Notifications[1860]: (process:5999): Gtk-WARNING **: Locale not supported by C library. Using the fallback 'C' locale}}.
| align="left"|{{ic|/etc/adjtime}}
+
| align="center"|{{ic|LOCALIZATION}}
+
 
|-
 
|-
| align="center"|Kernel modules
+
| 5 || Notice || notice || Events that are unusual, but not error conditions. || {{ic|systemd[1]: var.mount: Directory /var to mount over is not empty, mounting anyway}}. {{ic|gcr-prompter[4997]: Gtk: GtkDialog mapped without a transient parent. This is discouraged}}.
| align="left"|{{ic|/etc/modules-load.d/}}
+
|-
| align="center"|{{ic|HARDWARE}}
+
| 6 || Informational || info ||  Normal operational messages that require no action. || {{ic|lvm[585]:  7 logical volume(s) in volume group "archvg" now active}}.
 +
|-
 +
| 7 || Debug || debug || Information useful to developers for debugging the application. || {{ic|kdeinit5[1900]: powerdevil: Scheduling inhibition from ":1.14" "firefox" with cookie 13 and reason "screen"}}.
 
|}
 
|}
  
For legacy purposes, the '''DAEMONS''' section in {{ic|/etc/rc.conf}} is still compatible with systemd and can be used to start services at boot, even with a "pure" systemd service management. Alternatively, you may remove the {{ic|/etc/rc.conf}} file entirely and enable services in systemd. For each {{ic|<service_name>}} in the '''DAEMONS''' array in {{ic|/etc/rc.conf}}, type:
+
If issue you are looking for, was not found on according level, search it on couple of priority levels above and below. This rules are recommendations. Some errors considered a normal occasion for program so they marked low in priority by developer, and on the contrary, sometimes too many messages plaques too high priorities for them, but often it's an arguable situation. And often you really should solve an issue, also to understand architecture and adopt best practices.
# systemctl enable <service_name>.service
+
{{Tip|For a list of commonly used daemons with their initscripts and systemd equivalents, see [[Daemon#List_of_Daemons|this table]].}}
+
  
If {{ic|<service_name>.service}} does not exist:
+
Examples:
* the service file may not be available for systemd. In that case, you'll need to keep {{ic|rc.conf}} to start the service during boot up.
+
* Info message:  {{bc|pulseaudio[2047]: W: [pulseaudio] alsa-mixer.c: Volume element Master has 8 channels. That's too much! I can't handle that!}} It is an warning or error by definition.
* systemd may name services differently, e.g. {{ic|cronie.service}} replaces {{ic|crond}} init daemon; {{ic|alsa-store.service}} and {{ic|alsa-restore.service}} replace the {{ic|alsa}} init daemon. Another important instance is the {{ic|network}} daemon, which is replaced with another set of service files (see [[#Network]] for more details.)
+
* Plaguing alert message: {{bc|1=sudo[21711]:    user : a password is required ; TTY=pts/0 ; PWD=/home/user ; USER=root ; COMMAND=list /usr/bin/pacman --color auto -Sy}} The [https://bbs.archlinux.org/viewtopic.php?id=184455 reason] - user was manually added to sudoers file, not to wheel group, which is arguably normal action, but sudo produced an alert on every occasion.
{{Tip|You may look inside a package that contains daemon start scripts for service names. For instance:
+
$ pacman -Ql cronie
+
[...]
+
cronie /etc/rc.d/crond                            #<-- daemon initscript listed in the DAEMONS array (unused in a "pure" systemd configuration)
+
[...]
+
cronie /usr/lib/systemd/system/cronie.service    #<-- corresponding systemd daemon service
+
[...]
+
}}
+
* systemd will automatically handle the start order of these daemons.
+
* some services do not need to be explicitly enabled by the user. For instance, {{ic|dbus.service}} will automatically be enabled when {{ic|dbus-core}} is installed. Check the list of available services and their state using the {{ic|systemctl}} command.
+
  
==Writing custom .service files==
+
=== Filtering output ===
===Handling dependencies===
+
With systemd, dependencies can be resolved by designing the unit files correctly. The most typical case is that the unit {{ic|A}} requires the unit {{ic|B}} to be running before {{ic|A}} is started. In that case add {{ic|1=Requires=B}} and {{ic|1=After=B}} to the {{ic|[Unit]}} section of {{ic|A}}. If the dependency is optional, add {{ic|1=Wants=B}} and {{ic|1=After=B}} instead. Note that {{ic|1=Wants=}} and {{ic|1=Requires=}} do not imply {{ic|1=After=}}, meaning that if {{ic|1=After=}} is not specified, the two units will be started in parallel.
+
  
Dependencies are typically placed on services and not on targets. For example, {{ic|network.target}} is pulled in by whatever service configures your network interfaces, therefore ordering your custom unit after it is sufficient since {{ic|network.target}} is started anyway.
+
''journalctl'' allows you to filter the output by specific fields. Be aware that if there are many messages to display or filtering of large time span has to be done, the output of this command can be delayed for quite some time.
  
===Type===
+
{{Tip|While the journal is stored in a binary format, the content of stored messages is not modified. This means it is viewable with ''strings'', for example for recovery in an environment which does not have ''systemd'' installed. Example command:
There are several different start-up types to consider when writing a custom service file. This is set with the {{ic|1=Type=}} parameter in the {{ic|[Service]}} section. See {{ic|man systemd.service}} for a more detailed explanation.
+
{{bc|$ strings /mnt/arch/var/log/journal/af4967d77fba44c6b093d0e9862f6ddd/system.journal <nowiki>| grep -i</nowiki> ''message''}}
* {{ic|1=Type=simple}}: systemd considers the service to be started up immediately. The process must not fork. Do not use this type if other services need to be ordered on this service, unless it is socket activated.
+
}}
* {{ic|1=Type=forking}}: systemd considers the service started up once the process forks and the parent has exited. For classic daemons use this type unless you know that it is not necessary. You should specify {{ic|1=PIDFile=}} as well so systemd can keep track of the main process.
+
* {{ic|1=Type=oneshot}}: This is useful for scripts that do a single job and then exit. You may want to set {{ic|1=RemainAfterExit=}} as well so that systemd still considers the service as active after the process has exited.
+
* {{ic|1=Type=notify}}: Identical to {{ic|1=Type=simple}}, but with the stipulation that the daemon will send a signal to systemd when it is ready. The reference implementation for this notification is provided by {{ic|libsystemd-daemon.so}}.
+
* {{ic|1=Type=dbus}}: The service is considered ready when the specified {{ic|BusName}} appears on DBus's system bus.
+
  
===Replacing provided unit files===
+
Examples:
The unit files in {{ic|/etc/systemd/system/}} take precedence over the ones in {{ic|/usr/lib/systemd/system/}}.
+
To make your own version of a unit (which will not be destroyed by an upgrade), copy the old unit file from {{ic|/usr/lib/}} to {{ic|/etc/}} and make your changes there. Alternatively you can use {{ic|.include}} to parse an existing service file and then override or add new options. For example, if you simply want to add an additional dependency to a service file, you may use:
+
{{hc|/etc/systemd/system/<service-name>.service|
+
<nowiki>
+
.include /usr/lib/systemd/system/<service-name>.service
+
  
[Unit]
+
* Show all messages from this boot: {{bc|# journalctl -b}} However, often one is interested in messages not from the current, but from the previous boot (e.g. if an unrecoverable system crash happened). This is possible through optional offset parameter of the {{ic|-b}} flag: {{ic|journalctl -b -0}} shows messages from the current boot, {{ic|journalctl -b -1}} from the previous boot, {{ic|journalctl -b -2}} from the second previous and so on. See {{ic|man 1 journalctl}} for full description, the semantics is much more powerful.
Requires=<new dependency>
+
* Show all messages from date (and optional time): {{bc|1=# journalctl --since="2012-10-30 18:17:16"}}
After=<new dependency>
+
* Show all messages since 20 minutes ago: {{bc|1=# journalctl --since "20 min ago"}}
</nowiki>}}
+
* Follow new messages: {{bc|# journalctl -f}}
Then run the following for your changes to take effect:
+
* Show all messages by a specific executable: {{bc|# journalctl /usr/lib/systemd/systemd}}
# systemctl reenable <unit>
+
* Show all messages by a specific process: {{bc|1=# journalctl _PID=1}}
# systemctl restart <unit>
+
* Show all messages by a specific unit: {{bc|# journalctl -u netcfg}}
{{Tip|You can use {{ic|systemd-delta}} to see which unit files have been overridden and what exactly has been changed.}}
+
* Show kernel ring buffer: {{bc|1=# journalctl -k}}
 +
* Show auth.log equivalent by filtering on syslog facility: {{bc|1=# journalctl SYSLOG_FACILITY=10}}
 +
* Show only error, critical, and alert priority messages {{bc|# journalctl -p err..alert}} Numbers also can be used, {{ic|journalctl -p 3..1}}. If single number/keyword used, {{ic|journalctl -p 3}} - all higher priority levels also included.
  
===Syntax highlighting for systemd unit files within Vim===
+
See {{ic|man 1 journalctl}}, {{ic|man 7 systemd.journal-fields}}, or Lennart's [http://0pointer.de/blog/projects/journalctl.html blog post] for details.
Syntax highlighting for systemd unit files within [[Vim]] can be enabled by installing {{AUR|vim-systemd}} from the [[Arch User Repository|AUR]].
+
  
== FAQ ==
+
{{Tip|1=
For an up-to-date list of known issues, look at the upstream [http://cgit.freedesktop.org/systemd/systemd/tree/TODO TODO].
+
By default, ''journalctl'' truncates lines longer than screen width, but in some cases, it may be better to enable wrapping instead of truncating. This can be controlled by the {{ic|SYSTEMD_LESS}} [[environment variable]], which contains options passed to [[Core utilities#less|less]] (the default pager) and defaults to {{ic|FRSXMK}} (see {{ic|man 1 less}} and {{ic|man 1 journalctl}} for details).
  
{{FAQ
+
By omitting the {{ic|S}} option, the output will be wrapped instead of truncated. For example, start ''journalctl'' as follows:
|question=Why do I get log messages on my console?
+
|answer=You must set the kernel loglevel yourself. Historically, {{ic|/etc/rc.sysinit}} did this for us and set dmesg loglevel to {{ic|3}}, which was a reasonably quiet loglevel. Either add {{ic|1=loglevel=3}} or {{ic|quiet}} to your [[kernel parameters]].}}
+
  
{{FAQ
+
$ SYSTEMD_LESS=FRXMK journalctl
|question=How do I change the number of gettys running by default?
+
|answer=To add another getty, simply place another symlink for instantiating another getty in the {{ic|/etc/systemd/system/getty.target.wants/}} directory:
+
  
{{bc|<nowiki># ln -sf /usr/lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@tty9.service
+
If you would like to set this behaviour as default, [[Environment variables#Per_user|export]] the variable from {{ic|~/.bashrc}} or {{ic|~/.zshrc}}.
# systemctl daemon-reload
+
}}
# systemctl start getty@tty9.service</nowiki>}}
+
  
To remove a getty, simply remove the getty symlinks you want to get rid of in the {{ic|/etc/systemd/system/getty.target.wants/}} directory:
+
=== Journal size limit ===
  
{{bc|<nowiki># rm /etc/systemd/system/getty.target.wants/getty@tty5.service /etc/systemd/system/getty.target.wants/getty@tty6.service
+
If the journal is persistent (non-volatile), its size limit is set to a default value of 10% of the size of the underlying file system but capped to 4 GiB. For example, with {{ic|/var/log/journal/}} located on a 20 GiB partition, journal data may take up to 2 GiB. On a 50 GiB partition, it would max at 4 GiB.
# systemctl daemon-reload
+
# systemctl stop getty@tty5.service getty@tty6.service</nowiki>}}
+
  
systemd does not use the {{ic|/etc/inittab}} file.
+
The maximum size of the persistent journal can be controlled by uncommenting and changing the following:
  
{{Note|As of systemd 30, only 1 getty will be launched by default. If you switch to another tty, a getty will be launched there (socket-activation style). You can still force additional agetty processes to start using the above methods.}}}}
+
{{hc|/etc/systemd/journald.conf|2=
 +
SystemMaxUse=50M
 +
}}
  
{{FAQ
+
It is also possible to use the drop-in snippets configuration override mechanism rather than editing the global configuration file. In this case do not forget to place the overrides under the {{ic|[Journal]}} header:
|question=How do I get more verbose output during boot?
+
|answer=If you see no output at all in console after the initram message, this means you have the {{ic|quiet}} parameter in your kernel line. It's best to remove it, at least the first time you boot with systemd, to see if everything is ok. Then, You will see a list {{ic|[ OK ]}} in green or {{ic|[ FAILED ]}} in red.
+
  
Any messages are logged to the system log and if you want to find out about the status of your system run {{ic|systemctl}} (no root privileges required) or look at the boot/system log with {{ic|journalctl}}.
+
{{hc|/etc/systemd/journald.conf.d/00-journal-size.conf|2=
 +
[Journal]
 +
SystemMaxUse=50M
 
}}
 
}}
  
{{FAQ
+
See {{ic|man journald.conf}} for more info.
|question=How do I avoid clearing the console after boot?
+
|answer=Create a custom {{ic|getty@tty1.service}} file by copying {{ic|/usr/lib/systemd/system/getty@.service}} to {{ic|/etc/systemd/system/getty.target.wants/getty@tty1.service}} and change {{ic|TTYVTDisallocate}} to {{ic|no}}.
+
}}
+
  
{{FAQ
+
=== Clean journal files manually ===
|question=What kernel options do I need to enable in my kernel in case I do not use the official Arch kernel?
+
|answer=Kernels prior to 2.6.39 are unsupported.
+
  
This is a partial list of required/recommended options, there might be more:
+
Journal files can be globally removed from {{ic|/var/log/journal/}} using ''e.g.'' {{ic|rm}}, or can be trimmed according to various criteria using {{ic|journalctl}}. Examples:
  
{{bc|<nowiki>
+
* Remove archived journal files until the disk space they use falls below 100M: {{bc|1=# journalctl --vacuum-size=100M}}
CONFIG_AUDIT=y (recommended)
+
* Make all journal files contain no data older than 2 weeks. {{bc|1=# journalctl --vacuum-time=2weeks}}
CONFIG_AUDIT_LOGINUID_IMMUTABLE=y (not required, may break sysvinit compat)
+
CONFIG_CGROUPS=y
+
CONFIG_IPV6=[y|m] (highly recommended)
+
CONFIG_UEVENT_HELPER_PATH=""
+
CONFIG_DEVTMPFS=y
+
CONFIG_DEVTMPFS_MOUNT=y (required if you don't use an initramfs)
+
CONFIG_RTC_DRV_CMOS=y (highly recommended)
+
CONFIG_FANOTIFY=y (required for readahead)
+
CONFIG_AUTOFS4_FS=[y|m]
+
CONFIG_TMPFS_POSIX_ACL=y (recommended, if you want to use pam_systemd.so)
+
CONFIG_NAMESPACES=y (for Private*=yes)
+
CONFIG_NET_NS=y (for PrivateNetwork=yes)
+
CONFIG_FHANDLE=y
+
</nowiki>}}}}
+
  
{{FAQ
+
See {{ic|man journalctl}} for more info.
|question=What other units does a unit depend on?
+
|answer=For example, if you want to figure out which services a target like {{ic|multi-user.target}} pulls in, use something like this:
+
{{hc|$ systemctl show -p "Wants" multi-user.target|2=Wants=rc-local.service avahi-daemon.service rpcbind.service NetworkManager.service acpid.service dbus.service atd.service crond.service auditd.service ntpd.service udisks.service bluetooth.service cups.service wpa_supplicant.service getty.target modem-manager.service portreserve.service abrtd.service yum-updatesd.service upowerd.service test-first.service pcscd.service rsyslog.service haldaemon.service remote-fs.target plymouth-quit.service systemd-update-utmp-runlevel.service sendmail.service lvm2-monitor.service cpuspeed.service udev-post.service mdmonitor.service iscsid.service livesys.service livesys-late.service irqbalance.service iscsi.service}}
+
  
Instead of {{ic|Wants}} you might also try {{ic|WantedBy}}, {{ic|Requires}}, {{ic|RequiredBy}}, {{ic|Conflicts}}, {{ic|ConflictedBy}}, {{ic|Before}}, {{ic|After}} for the respective types of dependencies and their inverse.}}
+
=== Journald in conjunction with syslog ===
  
{{FAQ
+
Compatibility with a classic, non-journald aware [[Syslog-ng|syslog]] implementation can be provided by letting ''systemd'' forward all messages via the socket {{ic|/run/systemd/journal/syslog}}. To make the syslog daemon work with the journal, it has to bind to this socket instead of {{ic|/dev/log}} ([http://lwn.net/Articles/474968/ official announcement]).
|question=My computer shuts down, but the power stays on.
+
 
|answer=Use:
+
The default {{ic|journald.conf}} for forwarding to the socket is {{ic|1=ForwardToSyslog=no}} to avoid system overhead, because [[rsyslog]] or [[syslog-ng]] pull the messages from the journal by [http://lists.freedesktop.org/archives/systemd-devel/2014-August/022295.html#journald itself].
$ systemctl poweroff
+
 
Instead of {{ic|systemctl halt}}.}}
+
See [[Syslog-ng#Overview]] and [[Syslog-ng#syslog-ng and systemd journal]], or [[rsyslog]] respectively, for details on configuration.
 +
 
 +
=== Forward journald to /dev/tty12 ===
 +
 
 +
Create a [[#Editing provided units|drop-in directory]] {{ic|/etc/systemd/journald.conf.d}} and create a {{ic|fw-tty12.conf}} file in it:
  
{{FAQ
+
{{hc|1=/etc/systemd/journald.conf.d/fw-tty12.conf|2=
|question=After migrating to systemd, why won't my fakeRAID mount?
+
[Journal]
|answer=Be sure you use {{bc|# systemctl enable dmraid.service}}
+
ForwardToConsole=yes
 +
TTYPath=/dev/tty12
 +
MaxLevelConsole=info
 
}}
 
}}
  
{{FAQ
+
Then [[restart]] systemd-journald.
|question=How can I make a script start during the boot process?
+
|answer=Create a new file in {{ic|/etc/systemd/system}} (e.g. ''myscript''.service) and add the following contents:
+
{{bc|<nowiki>
+
[Unit]
+
Description=My script
+
  
[Service]
+
=== Specify a different journal to view ===
ExecStart=/usr/bin/my-script
+
There may be a need to check the logs of another system that is dead in the water, like booting from a live system to recover a production system. In such case, one can mount the disk in e.g. {{ic|/mnt}}, and specify the journal path via {{ic|-D}}/{{ic|--directory}}, like so:
  
[Install]
+
$ journalctl -D ''/mnt''/var/log/journal -xe
WantedBy=multi-user.target
+
 
</nowiki>}}
+
== Tips and tricks ==
Then
+
 
{{bc|# systemctl enable ''myscript''.service}}
+
=== Enable installed units by default ===
This example assumes you want your script to start up when the target multi-user is launched.
+
 
 +
{{Expansion|How does it work with instantiated units?}}
 +
 
 +
Arch Linux ships with {{ic|/usr/lib/systemd/system-preset/99-default.preset}} containing {{ic|disable *}}. This causes ''systemctl preset'' to disable all units by default, such that when a new package is installed, the user must manually enable the unit.
 +
 
 +
If this behavior is not desired, simply create a symlink from {{ic|/etc/systemd/system-preset/99-default.preset}} to {{ic|/dev/null}} in order to override the configuration file. This will cause ''systemctl preset'' to enable all units that get installed—regardless of unit type—unless specified in another file in one ''systemctl preset'''s configuration directories. User units are not affected. See the manpage for {{ic|systemd.preset}} for more information.
 +
 
 +
{{Note|Enabling all units by default may cause problems with packages that contain two or more mutually exclusive units. ''systemctl preset'' is designed to be used by distributions and spins or system administrators. In the case where two conflicting units would be enabled, you should explicitly specify which one is to be disabled in a preset configuration file as specified in the manpage for {{ic|systemd.preset}}.}}
 +
 
 +
== Troubleshooting ==
 +
 
 +
=== Investigating systemd errors ===
 +
 
 +
As an example, we will investigate an error with {{ic|systemd-modules-load}} service:
 +
 
 +
'''1.''' Lets find the ''systemd'' services which fail to start:
 +
 
 +
{{hc|1=$ systemctl --failed|2=
 +
systemd-modules-load.service  loaded '''failed failed'''  Load Kernel Modules
 
}}
 
}}
  
{{FAQ
+
'''2.''' Ok, we found a problem with {{ic|systemd-modules-load}} service. We want to know more:
|question=Status of .service says "active (exited)" in green. (e.g. iptables)
+
{{hc|$ systemctl status systemd-modules-load|2=
|answer=This is perfectly normal.
+
systemd-modules-load.service - Load Kernel Modules
In the case with iptables it is because there is no daemon to run, it is controlled in the kernel. Therefore it exits after the rules have been loaded.
+
  Loaded: loaded (/usr/lib/systemd/system/systemd-modules-load.service; static)
 +
  Active: '''failed''' (Result: exit-code) since So 2013-08-25 11:48:13 CEST; 32s ago
 +
    Docs: man:systemd-modules-load.service(8).
 +
          man:modules-load.d(5)
 +
  Process: '''15630''' ExecStart=/usr/lib/systemd/systemd-modules-load ('''code=exited, status=1/FAILURE''')
 +
}}
 +
If the {{ic|Process ID}} is not listed, just restart the failed service with {{ic|systemctl restart systemd-modules-load}}
  
To check if your iptables rules have been loaded properly:
+
'''3.''' Now we have the process id (PID) to investigate this error in depth. Enter the following command with the current {{ic|Process ID}} (here: 15630):
{{bc|iptables --list}}
+
{{hc|1=$ journalctl _PID=15630|2=
 +
-- Logs begin at Sa 2013-05-25 10:31:12 CEST, end at So 2013-08-25 11:51:17 CEST. --
 +
Aug 25 11:48:13 mypc systemd-modules-load[15630]: '''Failed to find module 'blacklist usblp''''
 +
Aug 25 11:48:13 mypc systemd-modules-load[15630]: '''Failed to find module 'install usblp /bin/false''''
 
}}
 
}}
  
{{FAQ
+
'''4.''' We see that some of the kernel module configs have wrong settings. Therefore we have a look at these settings in {{ic|/etc/modules-load.d/}}:
|question={{ic|Failed to issue method call: File exists}} error
+
{{hc|$ ls -Al /etc/modules-load.d/|
|answer=This happens when using {{ic|systemctl enable}} and the symlink it tries to create in {{ic|/etc/systemd/system/}} already exists. Typically this happens when switching from one display manager to another one (for instance GDM to KDM, which can be enabled with {{ic|gdm.service}} and {{ic|kdm.service}}, respectively) and the corresponding symlink {{ic|/etc/systemd/system/display-manager.service}} already exists.
+
...
To solve this problem, use {{ic|systemctl -f enable}} to overwrite an existing symlink.
+
-rw-r--r--  1 root root    79  1. Dez 2012  blacklist.conf
 +
-rw-r--r--  1 root root    1  2. Mär 14:30 encrypt.conf
 +
-rw-r--r--  1 root root    3  5. Dez 2012  printing.conf
 +
-rw-r--r--  1 root root    6 14. Jul 11:01 realtek.conf
 +
-rw-r--r--  1 root root    65  2. Jun 23:01 virtualbox.conf
 +
...
 
}}
 
}}
  
== Optimization ==
+
'''5.''' The {{ic|Failed to find module 'blacklist usblp'}} error message might be related to a wrong setting inside of {{ic|blacklist.conf}}. Lets deactivate it with inserting a trailing '''#''' before each option we found via step 3:
=== systemd-analyze ===
+
{{hc|/etc/modules-load.d/blacklist.conf|
Systemd provides a tool called {{ic|systemd-analyze}} that allows you to analyze your boot process so you can see which unit files are causing your boot process to slow down. You can then optimize your system accordingly. You have to install {{Pkg|python2-dbus}} and {{Pkg|python2-cairo}} to use it.
+
'''#''' blacklist usblp
 +
'''#''' install usblp /bin/false
 +
}}
  
To see how much time was spent in kernel-/userspace on boot, simply use:
+
'''6.''' Now, try to start {{ic|systemd-modules-load}}:
{{bc|$ systemd-analyze}}
+
$ systemctl start systemd-modules-load
{{Tip|If you add the {{ic|timestamp}} hook to your {{ic|HOOKS}} array in {{ic|/etc/mkinitcpio.conf}} and rebuild your initramfs, {{ic|systemd-analyze}} will also be able to show you how much time was spent in the initramfs.}}
+
If it was successful, this should not prompt anything. If you see any error, go back to step 3 and use the new PID for solving the errors left.
  
To list the started unit files, sorted by the time each of them took to start up:
+
If everything is ok, you can verify that the service was started successfully with:
{{bc|$ systemd-analyze blame}}
+
{{hc|$ systemctl status systemd-modules-load|2=
 +
systemd-modules-load.service - Load Kernel Modules
 +
  Loaded: '''loaded''' (/usr/lib/systemd/system/systemd-modules-load.service; static)
 +
  Active: '''active (exited)''' since So 2013-08-25 12:22:31 CEST; 34s ago
 +
    Docs: man:systemd-modules-load.service(8)
 +
          man:modules-load.d(5)
 +
Process: 19005 ExecStart=/usr/lib/systemd/systemd-modules-load (code=exited, status=0/SUCCESS)
 +
Aug 25 12:22:31 mypc systemd[1]: '''Started Load Kernel Modules'''.
 +
}}
  
You can also create a SVG file which describes your boot process grapically, similiar to [[Bootchart]]:
+
Often you can solve these kind of problems like shown above. For further investigation look at [[#Diagnosing boot problems]].
{{bc|$ systemd-analyze plot > plot.svg}}
+
  
====Enabling bootchart in conjunction with systemd====
+
=== Diagnosing boot problems ===
You can use a version of bootchart to visualize the boot sequence.
+
Since you are not able to put a second init into the kernel command line you won't be able to use any of the standard bootchart setups. However the {{AUR|bootchart2}} package from [[AUR]] comes with an undocumented systemd service. After you've installed bootchart2 do:
+
{{bc|# systemctl enable bootchart.service}}
+
Read the [https://github.com/mmeeks/bootchart bootchart documentation] for further details on using this version of bootchart.
+
  
=== Shell Shortcuts ===
+
''systemd'' has several options for diagnosing problems with the boot process. See [[boot debugging]] and the [http://freedesktop.org/wiki/Software/systemd/Debugging/ systemd debugging documentation].
systemd daemon management requires a bit more text entry to accomplish tasks such as start, stopped, enabling, checking status, etc. The following functions can be added to one's {{ic|~/.bashrc}} file to help streamline interactions with systemd and to improve the overall experience.
+
  
{{bc|<nowiki>if ! systemd-notify --booted; then # not using systemd
+
=== Diagnosing problems with a specific service ===
  alias start='sudo rc.d start'
+
  alias restart='sudo rc.d restart'
+
  alias stop='sudo rc.d stop'
+
else
+
  alias start='sudo systemctl start'
+
  alias restart='sudo systemctl restart'
+
  alias stop='sudo systemctl stop'
+
  alias enable='sudo systemctl enable'
+
  alias status='sudo systemctl status'
+
  alias disable='sudo systemctl disable'
+
fi
+
</nowiki>}}
+
  
=== Less output ===
+
{{Accuracy|This may not catch all errors such as missing libraries.|User talk:Alucryd#Plex}}
Change {{ic|verbose}} to {{ic|quiet}} on the bootloader's kernel line. For some systems, particularly those with an SSD, the slow performance of the TTY is actually a bottleneck, and so less output means faster booting.
+
  
=== Early start ===
+
If some ''systemd'' service misbehaves and you want to get more information about what is going on, set the {{ic|SYSTEMD_LOG_LEVEL}} [[environment variable]] to {{ic|debug}}. For example, to run the ''systemd-networkd'' daemon in debug mode:
One central feature of systemd is [[D-Bus]] and socket activation, this causes services to be started when they are first accessed, and is generally a good thing. However, if you know that a service (like [[ConsoleKit]]) will always be started during boot, then the overall boot time might be reduced by starting it as early as possible. This can be achieved (if the service file is set up for it, which in most cases it is) by issuing:
+
  
{{bc|# systemctl enable console-kit-daemon.service}}
+
# systemctl stop systemd-networkd
 +
# SYSTEMD_LOG_LEVEL=debug /lib/systemd/systemd-networkd
  
This will cause systemd to start ConsoleKit as soon as possible, without causing races with the socket or D-Bus activation.
+
Or, equivalently, modify the service file temporarily for gathering enough output. For example:
  
=== Automount ===
+
{{hc|/usr/lib/systemd/system/systemd-networkd.service|2=
The default setup will fsck and mount all filesystems before starting most daemons and services. If you have a large {{ic|/home}} partition, it might be better to allow services that do not depend on {{ic|/home}} to start while {{ic|/home}} is being fsck'ed. This can be achieved by adding the following options to the fstab entry of your {{ic|/home}} partition:
+
[Service]
 +
...
 +
Environment=SYSTEMD_LOG_LEVEL=debug
 +
....
 +
}}
  
noauto,x-systemd.automount
+
If debug information is required long-term, add the variable the [[#Editing provided units|regular]] way.
  
This will fsck and mount {{ic|/home}} when it is first accessed, and the kernel will buffer all file access to {{ic|/home}} until it is ready.
+
=== Shutdown/reboot takes terribly long ===
  
If you have encrypted filesystems with keyfiles, you can also add the {{ic|noauto}} parameter to the corresponding entries in {{ic|/etc/crypttab}}. systemd will then not open the encrypted device on boot, but instead wait until it is actually accessed and then automatically open it with the specified keyfile before mounting it. This might save a few seconds on boot if you are using an encrypted RAID device for example, because systemd doesn't have to wait for the device to become available. For example:
+
If the shutdown process takes a very long time (or seems to freeze) most likely a service not exiting is to blame. ''systemd'' waits some time for each service to exit before trying to kill it. To find out if you are affected, see [http://freedesktop.org/wiki/Software/systemd/Debugging/#shutdowncompleteseventually this article].
{{hc|/etc/crypttab|data /dev/md0 /root/key noauto}}
+
  
=== Readahead ===
+
=== Short lived processes do not seem to log any output ===
systemd comes with its own readahead implementation, this should in principle improve boot time. However, depending on your kernel version and the type of your hard drive, your mileage may vary (i.e. it might be slower). To enable, do:
+
  
{{bc|<nowiki># systemctl enable systemd-readahead-collect.service systemd-readahead-replay.service</nowiki>}}
+
If {{ic|journalctl -u foounit}} does not show any output for a short lived service, look at the PID instead. For example, if {{ic|systemd-modules-load.service}} fails, and {{ic|systemctl status systemd-modules-load}} shows that it ran as PID 123, then you might be able to see output in the journal for that PID, i.e. {{ic|journalctl -b _PID&#61;123}}. Metadata fields for the journal such as {{ic|_SYSTEMD_UNIT}} and {{ic|_COMM}} are collected asynchronously and rely on the {{ic|/proc}} directory for the process existing. Fixing this requires fixing the kernel to provide this data via a socket connection, similar to {{ic|SCM_CREDENTIALS}}.
  
Remember that in order for the readahead to work its magic, you should reboot a couple of times.
+
=== Boot time increasing over time ===
  
=== Replacing ConsoleKit with systemd-logind ===
+
After using {{ic|systemd-analyze}} a number of users have noticed that their boot time has increased significantly in comparison with what it used to be. After using {{ic|systemd-analyze blame}} [[NetworkManager]] is being reported as taking an unusually large amount of time to start.  
Starting with {{Pkg|polkit}} 0.107 (currently in [testing]), [[ConsoleKit]] can be completely replaced by {{ic|systemd-logind}}. However, there is currently no Display Manager in the Arch Linux repositories which natively supports {{ic|systemd-logind}} without still depending on [[ConsoleKit]]. The easiest method to be able to remove [[ConsoleKit]] is to [[Automatic_login_to_virtual_console#With_systemd|automatically login to a virtual console]] and [[Start_X_at_Boot|start X from there]]. It is important that, as mentioned in the latter article, the X server is started on the same virtual console that you log in to, otherwise systemd can not keep track of the user session. You can then simply remove {{ic|ck-launch-session}} from your {{ic|~/.xinitrc}}.
+
  
In order to check the status of your user session, you can use {{ic|loginctl}}. To see if your user session is properly set up, check if the following command contains {{ic|1=Active=yes}}. All {{Pkg|polkit}} actions like suspending the system or mounting external drives with [[Udisks]] should then work automatically.
+
The problem for some users has been due to {{ic|/var/log/journal}} becoming too large. This may have other impacts on performance, such as for {{ic|systemctl status}} or {{ic|journalctl}}. As such the solution is to remove every file within the folder (ideally making a backup of it somewhere, at least temporarily) and then setting a journal file size limit as described in [[#Journal size limit]].
$ loginctl show-session <session-id>
+
  
{{Note|If you use [[NetworkManager]], you have to recompile it with systemd support from the [[ABS]] by setting {{ic|1=--with-session-tracking=systemd}} in the [[PKGBUILD]].}}
+
=== systemd-tmpfiles-setup.service fails to start at boot ===
  
== Troubleshooting ==
+
Starting with systemd 219, {{ic|/usr/lib/tmpfiles.d/systemd.conf}} specifies ACL attributes for directories under {{ic|/var/log/journal}} and, therefore, requires ACL support to be enabled for the filesystem the journal resides on.
=== Shutdown/Reboot takes terribly long ===
+
If the shutdown process takes a very long time (or seems to freeze) most likely a service not exiting is to blame. systemd waits some time for each service to exit before trying to kill it.
+
To find out if you are affected see [http://freedesktop.org/wiki/Software/systemd/Debugging#Shutdown_Completes_Eventually this article].
+
==== SLiM and xfce-session ====
+
One setup that can produce a shutdown freeze is Xfce in conjunction with SLiM: Shutting down/rebooting using xfce-session will cause slim.service to hang for half a minute until systemd kills it the hard way.
+
One workaround is to create a modified {{ic|slim.service}}:
+
{{hc|/etc/systemd/system/slim.service|<nowiki>
+
[Unit]
+
Description=SLiM Simple Login Manager
+
After=systemd-user-sessions.service
+
  
[Service]
+
See [[Access Control Lists#Enabling ACL]] for instructions on how to enable ACL on the filesystem that houses {{ic|/var/log/journal}}.
Type=forking
+
PIDFile=/var/lock/slim.lock
+
ExecStart=/usr/bin/slim -d
+
ExecStop=/bin/kill -9 $MAINPID
+
ExecStopPost=/bin/rm /var/lock/slim.lock
+
  
[Install]
+
=== systemctl enable fails for symlinks in /etc/systemd/system ===
WantedBy=graphical.target</nowiki>}}
+
 
This causes SLiM to be terminated using SIGKILL. Since the lock file is also removed this does not cause a problem.
+
If {{ic|/etc/systemd/system/''foo''.service}} is a symlink and {{ic|systemctl enable ''foo''.service}} is run, it will fail with this error:
 +
 
 +
Failed to issue method call: No such file or directory
 +
 
 +
This is a [https://bugzilla.redhat.com/show_bug.cgi?id=955379#c14 design choice] of systemd. As a workaround, enabling by absolute path works:
 +
 
 +
# systemctl enable ''/absolute/path/foo''.service
 +
 
 +
=== dependent services are not started when starting a service manually===
 +
 
 +
{{Remove|Guesswork instead of actual research, and bug reports belong to the bug tracker, not to the wiki.|section=Subsection .22dependent services are not started when starting a service manually.22}}
 +
 
 +
One (in)famous example is {{ic|libvirtd.service}} which needs the {{ic|virtlogd.socket}} to function properly.
 +
 
 +
The dependencies in {{ic|/usr/lib/systemd/system/libvirtd.service}} are defined as
 +
[Install]
 +
WantedBy=multi-user.target
 +
Also=virtlockd.socket
 +
Also=virtlogd.socket
 +
This only defines the necessary/dependent sockets to be enabled services(i.e. as "autostart"), too - but does not start them whenever the DISABLED (= non-autostarting) service ist started manually e.g. by running {{ic|systemctl start libvirtd}}
  
=== If some services are failing to start ===
+
Thus the correct (?) way to manually start a service with dependent subservices once (instead of at each start of the system) probably is
 +
systemctl enable ServiceWithSubservices
 +
systemctl start ServiceWithSubservices
 +
systemctl disable ServiceWithSubservices
  
If your {{ic|/var/tmp}} is a symbolic link to {{ic|/tmp}}, expect some services to fail when started via systemd.  In these cases, the failure status of the processes (via {{ic|systemctl status <service>}}) will be {{ic|"226/NAMESPACE"}}.  To overcome this blocker, simply remove your {{ic|/var/tmp}} symlink and reinstall the {{pkg|filesystem}} package.
+
== See also ==
  
== See also==
+
*[http://www.freedesktop.org/wiki/Software/systemd Official web site]
*[http://www.freedesktop.org/wiki/Software/systemd Official Web Site]
+
*[[Wikipedia:systemd|Wikipedia article]]
*[http://0pointer.de/public/systemd-man/ Manual Pages]
+
*[http://0pointer.de/public/systemd-man/ Manual pages]
*[http://freedesktop.org/wiki/Software/systemd/Optimizations systemd Optimizations]
+
*[http://freedesktop.org/wiki/Software/systemd/Optimizations systemd optimizations]
 
*[http://www.freedesktop.org/wiki/Software/systemd/FrequentlyAskedQuestions FAQ]
 
*[http://www.freedesktop.org/wiki/Software/systemd/FrequentlyAskedQuestions FAQ]
*[http://www.freedesktop.org/wiki/Software/systemd/TipsAndTricks Tips And Tricks]
+
*[http://www.freedesktop.org/wiki/Software/systemd/TipsAndTricks Tips and tricks]
 
*[http://0pointer.de/public/systemd-ebook-psankar.pdf systemd for Administrators (PDF)]
 
*[http://0pointer.de/public/systemd-ebook-psankar.pdf systemd for Administrators (PDF)]
 
*[http://fedoraproject.org/wiki/Systemd About systemd on Fedora Project]
 
*[http://fedoraproject.org/wiki/Systemd About systemd on Fedora Project]
*[http://fedoraproject.org/wiki/How_to_debug_Systemd_problems How to debug Systemd problems]
+
*[http://fedoraproject.org/wiki/How_to_debug_Systemd_problems How to debug systemd problems]
*[http://www.h-online.com/open/features/Booting-up-Tools-and-tips-for-systemd-1570630.html Booting up: Tools and tips for systemd, a Linux init tool. In The H]
+
*[http://www.h-online.com/open/features/Control-Centre-The-systemd-Linux-init-system-1565543.html Two] [http://www.h-online.com/open/features/Booting-up-Tools-and-tips-for-systemd-1570630.html part] introductory article in ''The H Open'' magazine.
 
*[http://0pointer.de/blog/projects/systemd.html Lennart's blog story]
 
*[http://0pointer.de/blog/projects/systemd.html Lennart's blog story]
*[http://0pointer.de/blog/projects/systemd-update.html status update]
+
*[http://0pointer.de/blog/projects/systemd-update.html Status update]
*[http://0pointer.de/blog/projects/systemd-update-2.html status update2]
+
*[http://0pointer.de/blog/projects/systemd-update-2.html Status update2]
*[http://0pointer.de/blog/projects/systemd-update-3.html status update3]
+
*[http://0pointer.de/blog/projects/systemd-update-3.html Status update3]
*[http://0pointer.de/blog/projects/why.html most recent summary]
+
*[http://0pointer.de/blog/projects/why.html Most recent summary]
 +
*[http://fedoraproject.org/wiki/SysVinit_to_Systemd_Cheatsheet Fedora's SysVinit to systemd cheatsheet]
 +
*[http://wiki.gentoo.org/wiki/Systemd Gentoo Wiki systemd page]
 +
*[[Emacs#Syntax highlighting for systemd Files|Emacs Syntax highlighting for Systemd files]]

Latest revision as of 12:04, 18 July 2016

From the project web page:

systemd is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux control groups, supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic.
Note: For a detailed explanation as to why Arch has moved to systemd, see this forum post.

Basic systemctl usage

The main command used to introspect and control systemd is systemctl. Some of its uses are examining the system state and managing the system and services. See man systemctl for more details.

Tip:
  • You can use all of the following systemctl commands with the -H user@host switch to control a systemd instance on a remote machine. This will use SSH to connect to the remote systemd instance.
  • systemadm is the official graphical frontend for systemctl and is provided by the systemd-ui package.
  • Plasma users can install systemd-kcm as a graphical fronted for systemctl. After installing the module will be added under System administration.

Analyzing the system state

Show system status using:

$ systemctl status

List running units:

$ systemctl

or:

$ systemctl list-units

List failed units:

$ systemctl --failed

The available unit files can be seen in /usr/lib/systemd/system/ and /etc/systemd/system/ (the latter takes precedence). List installed unit files with:

$ systemctl list-unit-files

Using units

Units can be, for example, services (.service), mount points (.mount), devices (.device) or sockets (.socket).

When using systemctl, you generally have to specify the complete name of the unit file, including its suffix, for example sshd.socket. There are however a few short forms when specifying the unit in the following systemctl commands:

  • If you do not specify the suffix, systemctl will assume .service. For example, netctl and netctl.service are equivalent.
  • Mount points will automatically be translated into the appropriate .mount unit. For example, specifying /home is equivalent to home.mount.
  • Similar to mount points, devices are automatically translated into the appropriate .device unit, therefore specifying /dev/sda2 is equivalent to dev-sda2.device.

See man systemd.unit for details.

Note: Some unit names contain an @ sign (e.g. name@string.service): this means that they are instances of a template unit, whose actual file name does not contain the string part (e.g. name@.service). string is called the instance identifier, and is similar to an argument that is passed to the template unit when called with the systemctl command: in the unit file it will substitute the %i specifier.

To be more accurate, before trying to instantiate the name@.suffix template unit, systemd will actually look for a unit with the exact name@string.suffix file name, although by convention such a "clash" happens rarely, i.e. most unit files containing an @ sign are meant to be templates. Also, if a template unit is called without an instance identifier, it will just fail, since the %i specifier cannot be substituted.

Tip:
  • Most of the following commands also work if multiple units are specified, see man systemctl for more information.
  • The --now switch can be used in conjunction with enable, disable, and mask to respectively start, stop, or mask immediately the unit rather than after the next boot.
  • A package may offer units for different purposes. If you just installed a package, pacman -Qql package | grep -Fe .service -e .socket can be used to check and find them.

Start a unit immediately:

# systemctl start unit

Stop a unit immediately:

# systemctl stop unit

Restart a unit:

# systemctl restart unit

Ask a unit to reload its configuration:

# systemctl reload unit

Show the status of a unit, including whether it is running or not:

$ systemctl status unit

Check whether a unit is already enabled or not:

$ systemctl is-enabled unit

Enable a unit to be started on bootup:

# systemctl enable unit

Disable a unit to not start during bootup:

# systemctl disable unit

Mask a unit to make it impossible to start it:

# systemctl mask unit

Unmask a unit:

# systemctl unmask unit

Show the manual page associated with a unit (this has to be supported by the unit file):

$ systemctl help unit

Reload systemd, scanning for new or changed units:

# systemctl daemon-reload

Power management

polkit is necessary for power management as an unprivileged user. If you are in a local systemd-logind user session and no other session is active, the following commands will work without root privileges. If not (for example, because another user is logged into a tty), systemd will automatically ask you for the root password.

Shut down and reboot the system:

$ systemctl reboot

Shut down and power-off the system:

$ systemctl poweroff

Suspend the system:

$ systemctl suspend

Put the system into hibernation:

$ systemctl hibernate

Put the system into hybrid-sleep state (or suspend-to-both):

$ systemctl hybrid-sleep

Writing unit files

The syntax of systemd's unit files is inspired by XDG Desktop Entry Specification .desktop files, which are in turn inspired by Microsoft Windows .ini files. Unit files are loaded from two locations. From lowest to highest precedence they are:

  • /usr/lib/systemd/system/: units provided by installed packages
  • /etc/systemd/system/: units installed by the system administrator
Note:
  • The load paths are completely different when running systemd in user mode.
  • systemd unit names may only contain ASCII alphanumeric characters, underscores and periods. All other characters must be replaced by C-style "\x2d" escapes. See man systemd.unit and man systemd-escape for more information.

Look at the units installed by your packages for examples, as well as the annotated example section of man systemd.service.

Tip: Comments prepended with # may be used in unit-files as well, but only in new lines. Do not use end-line comments after systemd parameters or the unit will fail to activate.

Handling dependencies

With systemd, dependencies can be resolved by designing the unit files correctly. The most typical case is that the unit A requires the unit B to be running before A is started. In that case add Requires=B and After=B to the [Unit] section of A. If the dependency is optional, add Wants=B and After=B instead. Note that Wants= and Requires= do not imply After=, meaning that if After= is not specified, the two units will be started in parallel.

Dependencies are typically placed on services and not on targets. For example, network.target is pulled in by whatever service configures your network interfaces, therefore ordering your custom unit after it is sufficient since network.target is started anyway.

Service types

There are several different start-up types to consider when writing a custom service file. This is set with the Type= parameter in the [Service] section:

  • Type=simple (default): systemd considers the service to be started up immediately. The process must not fork. Do not use this type if other services need to be ordered on this service, unless it is socket activated.
  • Type=forking: systemd considers the service started up once the process forks and the parent has exited. For classic daemons use this type unless you know that it is not necessary. You should specify PIDFile= as well so systemd can keep track of the main process.
  • Type=oneshot: this is useful for scripts that do a single job and then exit. You may want to set RemainAfterExit=yes as well so that systemd still considers the service as active after the process has exited.
  • Type=notify: identical to Type=simple, but with the stipulation that the daemon will send a signal to systemd when it is ready. The reference implementation for this notification is provided by libsystemd-daemon.so.
  • Type=dbus: the service is considered ready when the specified BusName appears on DBus's system bus.
  • Type=idle: systemd will delay execution of the service binary until all jobs are dispatched. Other than that behavior is very similar to Type=simple.

See the systemd.service(5) man page for a more detailed explanation of the Type values.

Editing provided units

To avoid conflicts with pacman, unit files provided by packages should not be directly edited. There are two safe ways to modify a unit without touching the original file: create a new unit file which overwrites the original unit or create drop-in snippets which are applied on top of the original unit. For both methods, you must reload the unit afterwards to apply your changes. This can be done either by editing the unit with systemctl edit (which reloads the unit automatically) or by reloading all units with:

# systemctl daemon-reload
Tip:
  • You can use systemd-delta to see which unit files have been overridden or extended and what exactly has been changed.
  • Use systemctl cat unit to view the content of a unit file and all associated drop-in snippets.
  • Syntax highlighting for systemd unit files within Vim can be enabled by installing vim-systemd.

Replacement unit files

To replace the unit file /usr/lib/systemd/system/unit, create the file /etc/systemd/system/unit and reenable the unit to update the symlinks:

# systemctl reenable unit

Alternatively, run:

# systemctl edit --full unit

This opens /etc/systemd/system/unit in your editor (copying the installed version if it does not exist yet) and automatically reloads it when you finish editing.

Note: Pacman does not update the replacement unit files when the originals are updated, so this method can make system maintenance more difficult. For this reason the next approach is recommended.

Drop-in files

To create drop-in files for the unit file /usr/lib/systemd/system/unit, create the directory /etc/systemd/system/unit.d/ and place .conf files there to override or add new options. systemd will parse these .conf files and apply them on top of the original unit.

The easiest way to do this is to run:

# systemctl edit unit

This opens the file /etc/systemd/system/unit.d/override.conf in your text editor (creating it if necessary) and automatically reloads the unit when you are done editing.

Examples

For example, if you simply want to add an additional dependency to a unit, you may create the following file:

/etc/systemd/system/unit.d/customdependency.conf
[Unit]
Requires=new dependency
After=new dependency

As another example, in order to replace the ExecStart directive for a unit that is not of type oneshot, create the following file:

/etc/systemd/system/unit.d/customexec.conf
[Service]
ExecStart=
ExecStart=new command

Note how ExecStart must be cleared before being re-assigned ([1]). The same holds for every item that can be specified multiple times, e.g. OnCalendar for timers.

One more example to automatically restart a service:

/etc/systemd/system/unit.d/restart.conf
[Service]
Restart=always
RestartSec=30

Targets

Tango-edit-clear.pngThis article or section needs language, wiki syntax or style improvements.Tango-edit-clear.png

Reason: Unclear description, copy-pasted content (explicitly mentions "Fedora"). (Discuss in Talk:Systemd#Make section "Targets" more clearly)

systemd uses targets which serve a similar purpose as runlevels but act a little different. Each target is named instead of numbered and is intended to serve a specific purpose with the possibility of having multiple ones active at the same time. Some targets are implemented by inheriting all of the services of another target and adding additional services to it. There are systemd targets that mimic the common SystemVinit runlevels so you can still switch targets using the familiar telinit RUNLEVEL command.

Get current targets

The following should be used under systemd instead of running runlevel:

$ systemctl list-units --type=target

Create custom target

The runlevels that held a defined meaning under sysvinit (i.e., 0, 1, 3, 5, and 6); have a 1:1 mapping with a specific systemd target. Unfortunately, there is no good way to do the same for the user-defined runlevels like 2 and 4. If you make use of those it is suggested that you make a new named systemd target as /etc/systemd/system/your target that takes one of the existing runlevels as a base (you can look at /usr/lib/systemd/system/graphical.target as an example), make a directory /etc/systemd/system/your target.wants, and then symlink the additional services from /usr/lib/systemd/system/ that you wish to enable.

Targets table

SysV Runlevel systemd Target Notes
0 runlevel0.target, poweroff.target Halt the system.
1, s, single runlevel1.target, rescue.target Single user mode.
2, 4 runlevel2.target, runlevel4.target, multi-user.target User-defined/Site-specific runlevels. By default, identical to 3.
3 runlevel3.target, multi-user.target Multi-user, non-graphical. Users can usually login via multiple consoles or via the network.
5 runlevel5.target, graphical.target Multi-user, graphical. Usually has all the services of runlevel 3 plus a graphical login.
6 runlevel6.target, reboot.target Reboot
emergency emergency.target Emergency shell

Change current target

In systemd targets are exposed via target units. You can change them like this:

# systemctl isolate graphical.target

This will only change the current target, and has no effect on the next boot. This is equivalent to commands such as telinit 3 or telinit 5 in Sysvinit.

Change default target to boot into

The standard target is default.target, which is aliased by default to graphical.target (which roughly corresponds to the old runlevel 5). To change the default target at boot-time, append one of the following kernel parameters to your bootloader:

  • systemd.unit=multi-user.target (which roughly corresponds to the old runlevel 3),
  • systemd.unit=rescue.target (which roughly corresponds to the old runlevel 1).

Alternatively, you may leave the bootloader alone and change default.target. This can be done using systemctl:

# systemctl set-default multi-user.target

To be able to override the previously set default.target, use the force option:

# systemctl set-default -f multi-user.target

The effect of this command is output by systemctl; a symlink to the new default target is made at /etc/systemd/system/default.target.

Temporary files

"systemd-tmpfiles creates, deletes and cleans up volatile and temporary files and directories." It reads configuration files in /etc/tmpfiles.d/ and /usr/lib/tmpfiles.d/ to discover which actions to perform. Configuration files in the former directory take precedence over those in the latter directory.

Configuration files are usually provided together with service files, and they are named in the style of /usr/lib/tmpfiles.d/program.conf. For example, the Samba daemon expects the directory /run/samba to exist and to have the correct permissions. Therefore, the samba package ships with this configuration:

/usr/lib/tmpfiles.d/samba.conf
D /run/samba 0755 root root

Configuration files may also be used to write values into certain files on boot. For example, if you used /etc/rc.local to disable wakeup from USB devices with echo USBE > /proc/acpi/wakeup, you may use the following tmpfile instead:

/etc/tmpfiles.d/disable-usb-wake.conf
w /proc/acpi/wakeup - - - - USBE

See the systemd-tmpfiles(8) and tmpfiles.d(5) man pages for details.

Note: This method may not work to set options in /sys since the systemd-tmpfiles-setup service may run before the appropriate device modules is loaded. In this case you could check whether the module has a parameter for the option you want to set with modinfo module and set this option with a config file in /etc/modprobe.d. Otherwise you will have to write a udev rule to set the appropriate attribute as soon as the device appears.

Timers

A timer is a unit configuration file whose name ends with .timer and encodes information about a timer controlled and supervised by systemd, for timer-based activation. See systemd/Timers.

Note: Timers can replace cron functionality to a great extent. See systemd/Timers#As a cron replacement.

Mounting

Since systemd is a replacement for System V init, it is in charge of the mounts specified in /etc/fstab. In fact, it goes beyond the usual fstab capabilities, implementing special mount options prefixed with x-systemd.. See Fstab#Automount with systemd for an example of automounting (mounting on-demand) using these extensions. See [2] for the complete documentation of these extensions.

Journal

systemd has its own logging system called the journal; therefore, running a syslog daemon is no longer required. To read the log, use:

# journalctl

In Arch Linux, the directory /var/log/journal/ is a part of the systemd package, and the journal (when Storage= is set to auto in /etc/systemd/journald.conf) will write to /var/log/journal/. If you or some program delete that directory, systemd will not recreate it automatically and instead will write its logs to /run/systemd/journal in a nonpersistent way. However, the folder will be recreated when you set Storage=persistent and run systemctl restart systemd-journald (or reboot).

The systemd journal event notification message logging classification corresponds to classical BSD syslog protocol style (Wikipedia, RFC 5424). For more info see subsections Facility, Priority level, and for examples on how to use it in Filtering output.

Facility

A syslog facility code is used to specify the type of program that is logging the message RFC 5424 Section 6.2.1.

Facility code Keyword Description Info
0 kern kernel messages
1 user user-level messages
2 mail mail system Archaic POSIX still supported and sometimes used system, for more man mail)
3 daemon system daemons All deamons, including systemd and its subsystems
4 auth security/authorization messages Also watch for different facility 10
5 syslog messages generated internally by syslogd As it standartized for syslogd, not used by systemd (see facility 3)
6 lpr line printer subsystem (archaic subsystem)
7 news network news subsystem (archaic subsystem)
8 uucp UUCP subsystem (archaic subsystem)
9 clock daemon systemd-timesyncd
10 authpriv security/authorization messages Also watch for different facility 4
11 ftp FTP daemon
12 - NTP subsystem
13 - log audit
14 - log alert
15 cron scheduling daemon
16 local0 local use 0 (local0)
17 local1 local use 1 (local1)
18 local2 local use 2 (local2)
19 local3 local use 3 (local3)
20 local4 local use 4 (local4)
21 local5 local use 5 (local5)
22 local6 local use 6 (local6)
23 local7 local use 7 (local7)

So, useful facilities to watch: 0,1,3,4,9,10,15.

Priority level

A syslog severity code (in systemd called priority) is used to mark the importance of a message RFC 5424 Section 6.2.1.

Value Severity Keyword Description Examples
0 Emergency emerg System is unusable Severe Kernel BUG, systemd dumped core.
This level should not be used by applications.
1 Alert alert Should be corrected immediately Vital subsystem goes out of work. Data loss.
kernel: BUG: unable to handle kernel paging request at ffffc90403238ffc.
2 Critical crit Critical conditions Crashes, coredumps. Like familiar flash:
systemd-coredump[25319]: Process 25310 (plugin-containe) of user 1000 dumped core
Failure in the system primary application, like X11.
3 Error err Error conditions Not severe error reported:
kernel: usb 1-3: 3:1: cannot get freq at ep 0x84,
systemd[1]: Failed unmounting /var.,
libvirtd[1720]: internal error: Failed to initialize a valid firewall backend).
4 Warning warning May indicate that an error will occur if action is not taken. A non-root file system has only 1GB free.
org.freedesktop. Notifications[1860]: (process:5999): Gtk-WARNING **: Locale not supported by C library. Using the fallback 'C' locale.
5 Notice notice Events that are unusual, but not error conditions. systemd[1]: var.mount: Directory /var to mount over is not empty, mounting anyway. gcr-prompter[4997]: Gtk: GtkDialog mapped without a transient parent. This is discouraged.
6 Informational info Normal operational messages that require no action. lvm[585]: 7 logical volume(s) in volume group "archvg" now active.
7 Debug debug Information useful to developers for debugging the application. kdeinit5[1900]: powerdevil: Scheduling inhibition from ":1.14" "firefox" with cookie 13 and reason "screen".

If issue you are looking for, was not found on according level, search it on couple of priority levels above and below. This rules are recommendations. Some errors considered a normal occasion for program so they marked low in priority by developer, and on the contrary, sometimes too many messages plaques too high priorities for them, but often it's an arguable situation. And often you really should solve an issue, also to understand architecture and adopt best practices.

Examples:

  • Info message:
    pulseaudio[2047]: W: [pulseaudio] alsa-mixer.c: Volume element Master has 8 channels. That's too much! I can't handle that!
    It is an warning or error by definition.
  • Plaguing alert message:
    sudo[21711]:     user : a password is required ; TTY=pts/0 ; PWD=/home/user ; USER=root ; COMMAND=list /usr/bin/pacman --color auto -Sy
    The reason - user was manually added to sudoers file, not to wheel group, which is arguably normal action, but sudo produced an alert on every occasion.

Filtering output

journalctl allows you to filter the output by specific fields. Be aware that if there are many messages to display or filtering of large time span has to be done, the output of this command can be delayed for quite some time.

Tip: While the journal is stored in a binary format, the content of stored messages is not modified. This means it is viewable with strings, for example for recovery in an environment which does not have systemd installed. Example command:
$ strings /mnt/arch/var/log/journal/af4967d77fba44c6b093d0e9862f6ddd/system.journal | grep -i message

Examples:

  • Show all messages from this boot:
    # journalctl -b
    However, often one is interested in messages not from the current, but from the previous boot (e.g. if an unrecoverable system crash happened). This is possible through optional offset parameter of the -b flag: journalctl -b -0 shows messages from the current boot, journalctl -b -1 from the previous boot, journalctl -b -2 from the second previous and so on. See man 1 journalctl for full description, the semantics is much more powerful.
  • Show all messages from date (and optional time):
    # journalctl --since="2012-10-30 18:17:16"
  • Show all messages since 20 minutes ago:
    # journalctl --since "20 min ago"
  • Follow new messages:
    # journalctl -f
  • Show all messages by a specific executable:
    # journalctl /usr/lib/systemd/systemd
  • Show all messages by a specific process:
    # journalctl _PID=1
  • Show all messages by a specific unit:
    # journalctl -u netcfg
  • Show kernel ring buffer:
    # journalctl -k
  • Show auth.log equivalent by filtering on syslog facility:
    # journalctl SYSLOG_FACILITY=10
  • Show only error, critical, and alert priority messages
    # journalctl -p err..alert
    Numbers also can be used, journalctl -p 3..1. If single number/keyword used, journalctl -p 3 - all higher priority levels also included.

See man 1 journalctl, man 7 systemd.journal-fields, or Lennart's blog post for details.

Tip: By default, journalctl truncates lines longer than screen width, but in some cases, it may be better to enable wrapping instead of truncating. This can be controlled by the SYSTEMD_LESS environment variable, which contains options passed to less (the default pager) and defaults to FRSXMK (see man 1 less and man 1 journalctl for details).

By omitting the S option, the output will be wrapped instead of truncated. For example, start journalctl as follows:

$ SYSTEMD_LESS=FRXMK journalctl
If you would like to set this behaviour as default, export the variable from ~/.bashrc or ~/.zshrc.

Journal size limit

If the journal is persistent (non-volatile), its size limit is set to a default value of 10% of the size of the underlying file system but capped to 4 GiB. For example, with /var/log/journal/ located on a 20 GiB partition, journal data may take up to 2 GiB. On a 50 GiB partition, it would max at 4 GiB.

The maximum size of the persistent journal can be controlled by uncommenting and changing the following:

/etc/systemd/journald.conf
SystemMaxUse=50M

It is also possible to use the drop-in snippets configuration override mechanism rather than editing the global configuration file. In this case do not forget to place the overrides under the [Journal] header:

/etc/systemd/journald.conf.d/00-journal-size.conf
[Journal]
SystemMaxUse=50M

See man journald.conf for more info.

Clean journal files manually

Journal files can be globally removed from /var/log/journal/ using e.g. rm, or can be trimmed according to various criteria using journalctl. Examples:

  • Remove archived journal files until the disk space they use falls below 100M:
    # journalctl --vacuum-size=100M
  • Make all journal files contain no data older than 2 weeks.
    # journalctl --vacuum-time=2weeks

See man journalctl for more info.

Journald in conjunction with syslog

Compatibility with a classic, non-journald aware syslog implementation can be provided by letting systemd forward all messages via the socket /run/systemd/journal/syslog. To make the syslog daemon work with the journal, it has to bind to this socket instead of /dev/log (official announcement).

The default journald.conf for forwarding to the socket is ForwardToSyslog=no to avoid system overhead, because rsyslog or syslog-ng pull the messages from the journal by itself.

See Syslog-ng#Overview and Syslog-ng#syslog-ng and systemd journal, or rsyslog respectively, for details on configuration.

Forward journald to /dev/tty12

Create a drop-in directory /etc/systemd/journald.conf.d and create a fw-tty12.conf file in it:

/etc/systemd/journald.conf.d/fw-tty12.conf
[Journal]
ForwardToConsole=yes
TTYPath=/dev/tty12
MaxLevelConsole=info

Then restart systemd-journald.

Specify a different journal to view

There may be a need to check the logs of another system that is dead in the water, like booting from a live system to recover a production system. In such case, one can mount the disk in e.g. /mnt, and specify the journal path via -D/--directory, like so:

$ journalctl -D /mnt/var/log/journal -xe

Tips and tricks

Enable installed units by default

Tango-view-fullscreen.pngThis article or section needs expansion.Tango-view-fullscreen.png

Reason: How does it work with instantiated units? (Discuss in Talk:Systemd#)

Arch Linux ships with /usr/lib/systemd/system-preset/99-default.preset containing disable *. This causes systemctl preset to disable all units by default, such that when a new package is installed, the user must manually enable the unit.

If this behavior is not desired, simply create a symlink from /etc/systemd/system-preset/99-default.preset to /dev/null in order to override the configuration file. This will cause systemctl preset to enable all units that get installed—regardless of unit type—unless specified in another file in one systemctl preset's configuration directories. User units are not affected. See the manpage for systemd.preset for more information.

Note: Enabling all units by default may cause problems with packages that contain two or more mutually exclusive units. systemctl preset is designed to be used by distributions and spins or system administrators. In the case where two conflicting units would be enabled, you should explicitly specify which one is to be disabled in a preset configuration file as specified in the manpage for systemd.preset.

Troubleshooting

Investigating systemd errors

As an example, we will investigate an error with systemd-modules-load service:

1. Lets find the systemd services which fail to start:

$ systemctl --failed
systemd-modules-load.service   loaded failed failed  Load Kernel Modules

2. Ok, we found a problem with systemd-modules-load service. We want to know more:

$ systemctl status systemd-modules-load
systemd-modules-load.service - Load Kernel Modules
   Loaded: loaded (/usr/lib/systemd/system/systemd-modules-load.service; static)
   Active: failed (Result: exit-code) since So 2013-08-25 11:48:13 CEST; 32s ago
     Docs: man:systemd-modules-load.service(8).
           man:modules-load.d(5)
  Process: 15630 ExecStart=/usr/lib/systemd/systemd-modules-load (code=exited, status=1/FAILURE)

If the Process ID is not listed, just restart the failed service with systemctl restart systemd-modules-load

3. Now we have the process id (PID) to investigate this error in depth. Enter the following command with the current Process ID (here: 15630):

$ journalctl _PID=15630
-- Logs begin at Sa 2013-05-25 10:31:12 CEST, end at So 2013-08-25 11:51:17 CEST. --
Aug 25 11:48:13 mypc systemd-modules-load[15630]: Failed to find module 'blacklist usblp'
Aug 25 11:48:13 mypc systemd-modules-load[15630]: Failed to find module 'install usblp /bin/false'

4. We see that some of the kernel module configs have wrong settings. Therefore we have a look at these settings in /etc/modules-load.d/:

$ ls -Al /etc/modules-load.d/
...
-rw-r--r--   1 root root    79  1. Dez 2012  blacklist.conf
-rw-r--r--   1 root root     1  2. Mär 14:30 encrypt.conf
-rw-r--r--   1 root root     3  5. Dez 2012  printing.conf
-rw-r--r--   1 root root     6 14. Jul 11:01 realtek.conf
-rw-r--r--   1 root root    65  2. Jun 23:01 virtualbox.conf
...

5. The Failed to find module 'blacklist usblp' error message might be related to a wrong setting inside of blacklist.conf. Lets deactivate it with inserting a trailing # before each option we found via step 3:

/etc/modules-load.d/blacklist.conf
# blacklist usblp
# install usblp /bin/false

6. Now, try to start systemd-modules-load:

$ systemctl start systemd-modules-load

If it was successful, this should not prompt anything. If you see any error, go back to step 3 and use the new PID for solving the errors left.

If everything is ok, you can verify that the service was started successfully with:

$ systemctl status systemd-modules-load
systemd-modules-load.service - Load Kernel Modules
   Loaded: loaded (/usr/lib/systemd/system/systemd-modules-load.service; static)
   Active: active (exited) since So 2013-08-25 12:22:31 CEST; 34s ago
     Docs: man:systemd-modules-load.service(8)
           man:modules-load.d(5)
 Process: 19005 ExecStart=/usr/lib/systemd/systemd-modules-load (code=exited, status=0/SUCCESS)
Aug 25 12:22:31 mypc systemd[1]: Started Load Kernel Modules.

Often you can solve these kind of problems like shown above. For further investigation look at #Diagnosing boot problems.

Diagnosing boot problems

systemd has several options for diagnosing problems with the boot process. See boot debugging and the systemd debugging documentation.

Diagnosing problems with a specific service

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: This may not catch all errors such as missing libraries. (Discuss in User talk:Alucryd#Plex)

If some systemd service misbehaves and you want to get more information about what is going on, set the SYSTEMD_LOG_LEVEL environment variable to debug. For example, to run the systemd-networkd daemon in debug mode:

# systemctl stop systemd-networkd
# SYSTEMD_LOG_LEVEL=debug /lib/systemd/systemd-networkd

Or, equivalently, modify the service file temporarily for gathering enough output. For example:

/usr/lib/systemd/system/systemd-networkd.service
[Service]
...
Environment=SYSTEMD_LOG_LEVEL=debug
....

If debug information is required long-term, add the variable the regular way.

Shutdown/reboot takes terribly long

If the shutdown process takes a very long time (or seems to freeze) most likely a service not exiting is to blame. systemd waits some time for each service to exit before trying to kill it. To find out if you are affected, see this article.

Short lived processes do not seem to log any output

If journalctl -u foounit does not show any output for a short lived service, look at the PID instead. For example, if systemd-modules-load.service fails, and systemctl status systemd-modules-load shows that it ran as PID 123, then you might be able to see output in the journal for that PID, i.e. journalctl -b _PID=123. Metadata fields for the journal such as _SYSTEMD_UNIT and _COMM are collected asynchronously and rely on the /proc directory for the process existing. Fixing this requires fixing the kernel to provide this data via a socket connection, similar to SCM_CREDENTIALS.

Boot time increasing over time

After using systemd-analyze a number of users have noticed that their boot time has increased significantly in comparison with what it used to be. After using systemd-analyze blame NetworkManager is being reported as taking an unusually large amount of time to start.

The problem for some users has been due to /var/log/journal becoming too large. This may have other impacts on performance, such as for systemctl status or journalctl. As such the solution is to remove every file within the folder (ideally making a backup of it somewhere, at least temporarily) and then setting a journal file size limit as described in #Journal size limit.

systemd-tmpfiles-setup.service fails to start at boot

Starting with systemd 219, /usr/lib/tmpfiles.d/systemd.conf specifies ACL attributes for directories under /var/log/journal and, therefore, requires ACL support to be enabled for the filesystem the journal resides on.

See Access Control Lists#Enabling ACL for instructions on how to enable ACL on the filesystem that houses /var/log/journal.

systemctl enable fails for symlinks in /etc/systemd/system

If /etc/systemd/system/foo.service is a symlink and systemctl enable foo.service is run, it will fail with this error:

Failed to issue method call: No such file or directory

This is a design choice of systemd. As a workaround, enabling by absolute path works:

# systemctl enable /absolute/path/foo.service

dependent services are not started when starting a service manually

Tango-edit-cut.pngThis section is being considered for removal.Tango-edit-cut.png

Reason: Guesswork instead of actual research, and bug reports belong to the bug tracker, not to the wiki. (Discuss in Talk:Systemd#Subsection .22dependent services are not started when starting a service manually.22)

One (in)famous example is libvirtd.service which needs the virtlogd.socket to function properly.

The dependencies in /usr/lib/systemd/system/libvirtd.service are defined as

[Install]
WantedBy=multi-user.target
Also=virtlockd.socket
Also=virtlogd.socket

This only defines the necessary/dependent sockets to be enabled services(i.e. as "autostart"), too - but does not start them whenever the DISABLED (= non-autostarting) service ist started manually e.g. by running systemctl start libvirtd

Thus the correct (?) way to manually start a service with dependent subservices once (instead of at each start of the system) probably is

systemctl enable ServiceWithSubservices
systemctl start ServiceWithSubservices
systemctl disable ServiceWithSubservices

See also