Systemd/ko

systemd는 리눅스 시스템용 최신 SysV 방식의 init 및 rc(run command) 를 대체하는 시스템입니다. 젠투에서는 대안 init 시스템으로 지원합니다.

커널
systemd에서는 최신 리눅스 커널 기능의 대부분을 사용할 수 있습니다. 이제 최소 커널 지원 버전은 2.6.39입니다. 최근의 에서는 systemd용 필수, 선택 커널 옵션을 선택하는 간편한 수단을 도입했습니다:

커널 옵션(를 사용하지 않는 경우의 옵션)을 직접 설정하려면 다음 커널 옵션이 필요하거나 추천합니다:

UEFI 시스템에서는 다음 옵션을 활성화하십시오:

시스템에서 BFQ 스케쥴러를 사용한다면 "Enable the block layer -> IO Schedulers"의 BFQ 업스트림에서 "BFQ hierarchical scheduling support" 활성화를 추천합니다.

최신 목록은, 업스트림 README 파일에서 "REQUIREMENTS" 섹션을 참고하십시오.

디렉터리
디렉터리는 systemd가 사용하며 또한 기타 프로그램의 경우 파일, 소켓, 상태 파일과 같은 실행 시간 데이터를 저장하는 반영구 저장소로 활용합니다.

systemd 꾸러미에서는 자체적으로 디렉터리를 만듭니다. 그러나 이러한 변경 동작은 OpenRC 에서도 마찬가지로 자동 마운트와 타 프로그램 꾸러미에서의 해당 파일 시스템 사용에 영향을 준다는 점을 참고하셨으면 합니다.

업스트림에서는 로 연결하는 심볼릭 링크 파일만 지원합니다. 이 심볼릭 링크를 만들지 않으면 mount 와 df 에서 문제가 발생합니다. 예전에는 일부 프로그램에서 (마운트 옵션과 같은) 정보를 에 써서 일반 파일이었습니다. 이제 모든 프로그램이 이 문제를 해결하도록 지원합니다. 여전히, 이 파일을 심볼릭 링크로 만들기 전에 보고된 문제점으로 하여금 시스템이 영향을 받는지 알아보려면 버그를 확인해보십시오.

심볼릭 링크를 만들려면 다음 명령을 실행하십시오:

부팅 시간에 /usr이 나타나는지 확인하기
For a split configuration, use an initramfs to mount  before starting systemd. See the Initramfs Gentoo Guide for instructions.

LVM2 와 Initramfs 사용하기
When sys-fs/lvm2 is used and the system is booted using an initramfs, the initramfs will have to be created using by running:

is either  or one of the other genkernel targets which imply the creation of an initramfs. For more information, look at the output of genkernel --help:

When LVM is used, the lvmetad daemon needs to be started as well. Otherwise systemd will be unable to mount LVM volumes. lvmetad can be enabled in :

설치
contains udev. Once installed, can be removed as systemd will be the provider for.

Enable the  USE flag globally (in ). The  USE flag should also be disabled to prevent conflicts with the systemd-logind service. It is also possible to switch to a systemd subprofile to use saner USE flags defaults in which case it is not necessary to change :

마지막으로 새 플래그로 시스템을 업데이트하십시오:

의존성 문제가 발생하면(를 막는 ), 가 world 파일에 등록한 상태일수도 있습니다. 선택을 취소하여 이 문제를 해결해보십시오:

systemd로 부팅
In order to run systemd, switch the init that the executable kernel (or the initramfs) uses.

The following subsections document how to switch the init in one of the boot managers or the kernel.

Grub Legacy (0.x)
The  argument should be added to the kernel command-line. An example excerpt from would look like so:

Should the system boot using OpenRC, try using  instead of.

Grub 2
When is used, add the init option to GRUB_CMDLINE_LINUX :

When the GRUB 2 configuration file is written by hand (experts only), append the  parameter to the   or   command.

When using genkernel-next's initrd, use  instead of.

In kernel config
The init configuration can also be hard-coded in the kernel configuration. See "Processor type and features -> Built-in kernel command line". Note that this technique works for both grub</tt> and grub2</tt>.

Setting root password
At this point don't forget to set the system's root password. If something goes wrong, systemd will prompt for the root password to go into maintenance mode.

Post-installation configuration
systemd supports a few system configuration files to set the most basic system details.

Hostname
To set the hostname, create/edit and simply provide the desired hostname.

When booted using systemd, a tool called exists for editing  and. To change the hostname, run:

Refer to for more options.

Locale
Usually, locales will be properly migrated from OpenRC when installing systemd. When required, the locale can be set in as per the Gentoo handbook instructions:

Once booted with systemd, the tool localectl</tt> is used to set locale and console or X11 keymaps. To change the system locale, run the following command:

To change the virtual console keymap:

And finally, to set the X11 layout:

If needed the model, variant and options can be specified as well:

Time and date
Time and date can be set using the timedatectl</tt> utility. That will also allow users to set up synchronization without needing to rely on or other providers than systemd's own implementation.

To learn how to use timedatectl</tt> simply run:

Automatic module loading
Automatic module loading is configured in a different file, or rather directory of files. The configuration files are stored in. On boot every file with a list of modules will be loaded. The file format is a list of modules separated by newlines and can have any name as long as it ends with. The module loading can be separated by program, service or whatever way that fits personal preference. An example virtualbox.conf</tt> is listed below:

systemd-networkd
systemd-networkd is useful for simple configuration of wired network interfaces. It is disabled by default.

To configure systemd-networkd, create a file under. See systemd.network(5) for reference. A simple DHCP configuration is given below:

Note that systemd-networkd does not update by default. To have systemd manage the DNS settings, replace with a symlink and start systemd-resolved.

NetworkManager
Often NetworkManager is used to configure network settings. For that purpose, simply run the following command when using an X11-powered desktop:

If that is not the case and the network needs to be configured from console, give nmcli a try, or follow a guided configuration process through nmtui</tt>:

nmtui is a curses frontend that will guide the user in the process while running in console mode.

Handling of log files
systemd has its own way of handling log files without needing to rely on any external log system (like or ). Messages can now be read with journalctl</tt>. Anyway, it can still be configured to use a preferred external tool for handling them. Please type man journald.conf for learning about how to configure journald to suit personal needs.

/tmp is now in tmpfs
Unless some other filesystem is explicitly mounted to in, systemd will mount  as tmpfs. That means it will be emptied on every boot and its size will be limited to 50% of the system's RAM size. To know why this is the desired behavior and how to modify it, take a look at API File Systems.

Configure verbosity of boot process
When migrating to systemd users usually notice differences regarding verbosity of boot process:


 * The boot option  not only influences the kernel output, but also that of systemd itself. Then, while setting up systemd for the machine, drop the option to see any errors could arise more easily. After that, add it back to get a quiet (and faster) boot.
 * Even passing the  boot option, systemd can still be configured to show its status by also passing.
 * When not using the  boot option, some messages might be overwriting consoles. That is caused by the kernel configuration (see man 5 proc and look for ). To tweak it pass the   boot parameter to the kernel (and update the value according to preference, for instance set a lower value like 1).

Services
At some point the system will need to be rebooted in order to get systemd running (in system mode). Be sure to read all of this document to ensure systemd is configured as completely as possible before rebooting. Note that journalctl</tt> works with systemd not running, but that systemctl</tt> will not do anything useful without systemd running. Complete the service configuration (enabling and starting of services) after logging in to the system running systemd.

OpenRC services
Although systemd originally intended to support running old init.d scripts, that support is not suited well for a dependency-based RC like OpenRC and thus is completely disabled on Gentoo. OpenRC provides additional measures to ensure that init.d scripts can't be run when OpenRC was not used to boot the system (otherwise the results would be unpredictable).

Listing available services
All available service units can be listed using the  argument of systemctl</tt>:

The following file suffixes are of interest:

Alternatively the systemctl</tt> tool can be used to list all services (including implicit ones):

And finally check for services that failed to start:

Enabling, disabling, starting, and stopping services
The usual way of enabling a service is using the following command:

Services can be disabled likewise:

These commands enable services using their default name in default target (both specified in "Install" section of the service file). However, sometimes services either don't provide that information or users prefer to have another name/target.

Note that these commands only enable or disable the system to be started on a next boot; to start the service right now, use:

Services can be stopped likewise:

Installing custom unit files
Custom unit files can be placed in, where they will be recognized after running systemctl daemon-reload</tt>:

is reserved for service files installed by the package manager.

Customizing unit files
When only minor changes to a unit are needed, there's no need to create a full copy of the original unit file in. Overriding settings in a package management provided unit can be achieved by drop-in files in a directory named after the original unit (e.g. ) in.

A reload of systemd is needed to inform it of the changes:

Then the service needs to be restarted to apply the changes:

Verify that the changed property was applied to the service:

Enabling a service under a custom name
When the name provided by "Alias" in the unit's "[Install]" section does not meet the expectations and providing a permanent new value for this through a customization is not desired, a symlink can be created manually in. The name of the directory can either specify a target or another service which will depend on the new one.

For example, to install as  in the :

To disable the service, just remove the symlink:

Native services
Some of Gentoo packages already install systemd unit files. For these services, it is enough to enable them. A quick summary of packages installing unit files can be seen on systemd eclass users list.

The following table lists systemd services matching OpenRC ones:

Timer services
Since version 197 systemd supports timers, making cron unnecessary on a systemd system. Since version 212 persistent services are supported, replacing even anacron. Persistent timers are run at the next opportunity if the system was powered down when the timer was scheduled.

The following is an example on how to make a simple timer that runs in the context of a user. It will even run if the user is not logged in. Every timed service needs a timer and a service file that is activated by the timer as follows:

Firstly, tell systemd to rescan the service files:

It is possible to trigger the backup manually by running the following command:

Start and stop the timer manually as follows:

Finally, to activate the timer at every system start, run:

To check the last results of running the service:

Emailing failures
If a timed service runs and fails an e-mail can be send out to inform the user or administrator. This is possible with the "OnFailure" stanza which specifies what should happen if a service fails. A failure is detected by a non-zero return code of the invoked script.

For that change the script as follows:

This requires to have the service installed, which can be found in kylemanna's systemd-utils repository.

Replacing cron
The above timer and service files can also be added to to make them available system-wide. The install section should then say  to enable the service at system start.

However, cron also runs the scripts in and other locations. Several packages place scripts there that they expect to be run daily. This behavior can be emulated with systemd by installing. Then activate the new cron replacement with the following commands:

Troubleshooting

 * Upstream debugging guide
 * Upstream debugging guide
 * Upstream debugging guide

Graphical sessions opened in random places
By default systemd only launches a getty</tt> process when it's going to be used. This causes some display managers (like GDM) to use the remaining TTYs for opening graphical sessions on demand, which can result in having consoles and graphical sessions placed randomly depending on the order they were used.

To stick with a more "classical" behavior (i.e, consoles placed from to  and graphical sessions using the remaining TTYs) force it to always launch getty</tt> on those:

lvm
When switching from OpenRC to systemd and lvm is needed to properly mount the system volumes, activate the lvm service:

While it might not be needed for activation of the root volume (if lvm is integrated into the initramfs) it might not work for other lvm volumes, unless the service is activated.

systemd-bootchart
As systemd-bootchart attempts to start, reconfigure it to invoke systemd instead:

The result of the bootchart is a report in SVG format located in.

syslog-ng conflicts with systemd
systemd creates as datagram socket  so syslog-ng needs to be told to read from a unix-dgram instead of a unix-stream as otherwise syslog-ng would be using a "wrong" stream:

sys-fs/cryptsetup configuration
systemd does not seem to respect (see ) so it needs to be configured through the  file:

You may need to create a new service file from your file. To do this, enable the  USE flag for. It will install. Executing it will create a service file in, which you can now copy to , adjust manually and add to the desired runlevel.

Check for units that failed to start
Check for units that failed to start with:

Enable Debug Mode
To get more informations set the following in :

Or enable the debug-shell, that opens a terminal at tty9. This helps to debug services during the boot process.

e4rat usage
Please remember to edit setting 'init' to, otherwise it will keep booting OpenRC.

GRSecurity hardening
With grsecurity enabled, systemd-networkd might log the following error:

The error raises due to systemd-networkd working under a non-root user with grsecurity refusing access to the complete structure for such users. To disable this option, disable the kernel option.

External resources

 * FAQ
 * Tips and tricks