Difference between revisions of "Systemd"
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$ systemctl stop firewalld | $ systemctl stop firewalld | ||
$ systemctl mask firewalld | $ systemctl mask firewalld | ||
+ | |||
+ | * Get default target: | ||
+ | $ systemctl get-default # note: usually will be "graphical.target" ("runlevel 5") | ||
+ | * Set default target: | ||
+ | $ systemctl set-default multi-user.target ("runlevel 3") | ||
+ | * Change to a new target: | ||
+ | $ systemctl isolate multi-user.target | ||
+ | * Switch to the rescue environment ("runlevel 1") | ||
+ | $ systemctl rescue | ||
+ | * Switch to default target: | ||
+ | $ systemctl default | ||
+ | * Reboot server: | ||
+ | $ systemctl isolate reboot.target | ||
+ | * Power off server: | ||
+ | $ systemctl poweroff | ||
+ | #~or~ | ||
+ | $ systemctl isolate shutdown.target | ||
* Miscellaneous: | * Miscellaneous: | ||
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$ journalctl --since 03:00 --until "1 hour ago" | $ journalctl --since 03:00 --until "1 hour ago" | ||
$ journalctl -u ssh.service --since="5 minutes ago" | $ journalctl -u ssh.service --since="5 minutes ago" | ||
+ | |||
+ | * Show BIOS boot up sequence: | ||
+ | $ journalctl --no-hostname -o short-monotonic --boot -0 | ||
; Cleanup journal logs (i.e., the self-maintenance method is to vacuum the logs by size or time): | ; Cleanup journal logs (i.e., the self-maintenance method is to vacuum the logs by size or time): | ||
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Finally, you can set the following in <code>/etc/systemd/journald.conf</code>: | Finally, you can set the following in <code>/etc/systemd/journald.conf</code>: | ||
SystemMaxUse=100M | SystemMaxUse=100M | ||
+ | |||
+ | * Misc: | ||
+ | <pre> | ||
+ | $ journalctl --utc -ke | ||
+ | </pre> | ||
+ | Where: | ||
+ | :<code>--utc</code>: show time in Coordinated Universal Time (UTC). | ||
+ | :<code>-ke</code>: show only kernel messages and jumps to end of the log. | ||
See: <code>man journalctl</code> for more information. | See: <code>man journalctl</code> for more information. | ||
Line 336: | Line 364: | ||
$ systemd-cgtop # Show top control groups by their resource usage | $ systemd-cgtop # Show top control groups by their resource usage | ||
$ systemd-path # List and query system and user paths | $ systemd-path # List and query system and user paths | ||
+ | |||
+ | * List content of an initramfs image: | ||
+ | $ lsinitramfs /boot/initrd.img-$(uname -r) | less | ||
==External links== | ==External links== | ||
− | *[http://freedesktop.org/wiki/Software/systemd/ Official website] | + | * [http://freedesktop.org/wiki/Software/systemd/ Official website] |
− | *[https://www.digitalocean.com/community/tutorials/how-to-use-journalctl-to-view-and-manipulate-systemd-logs How To Use Journalctl to View and Manipulate Systemd Logs] | + | * Full systemd documentation can be found by running <code>man 5 systemd.unit</code> |
− | *[https://tlhp.cf/lennart-poettering-su/ Explanation of `machinectl`] — the `su` replacement on systemd | + | * [https://www.digitalocean.com/community/tutorials/how-to-use-journalctl-to-view-and-manipulate-systemd-logs How To Use Journalctl to View and Manipulate Systemd Logs] |
+ | * [https://tlhp.cf/lennart-poettering-su/ Explanation of `machinectl`] — the `su` replacement on systemd | ||
[[Category:Linux Command Line Tools]] | [[Category:Linux Command Line Tools]] |
Latest revision as of 00:06, 11 April 2023
systemd is a suite of system management daemons, libraries, and utilities designed as a central management and configuration platform for the Linux computer operating system.
Contents
Example usage
- Check if you are running "init" or "systemd":
$ cat /proc/1/comm systemd
- Restart network:
$ systemctl restart network.target
- stop and mask the firewalld service (see: iptables vs. firewalld):
$ systemctl stop firewalld $ systemctl mask firewalld
- Get default target:
$ systemctl get-default # note: usually will be "graphical.target" ("runlevel 5")
- Set default target:
$ systemctl set-default multi-user.target ("runlevel 3")
- Change to a new target:
$ systemctl isolate multi-user.target
- Switch to the rescue environment ("runlevel 1")
$ systemctl rescue
- Switch to default target:
$ systemctl default
- Reboot server:
$ systemctl isolate reboot.target
- Power off server:
$ systemctl poweroff #~or~ $ systemctl isolate shutdown.target
- Miscellaneous:
$ systemctl list-units $ systemctl list-units -t service $ systemctl list-units | grep .service $ systemctl list-units -t target $ systemctl list-unit-files $ systemctl list-unit-files -t target $ systemctl list-dependencies multi-user.target $ systemctl [status|stop|enable|disable|restart] ssh.service $ systemctl is-enabled ssh.service $ systemctl edit --full docker.service $ systemctl cat ssh.service $ systemctl show --property=ExecStart docker.service $ systemctl is-active docker active $ systemctl [reboot|poweroff|suspend]
- List all loaded units:
$ systemctl list-units -all | grep loaded | awk '{print $1;}'
- List all enabled units:
$ systemctl list-unit-files | grep enabled | awk '{print $1;}'
- List all loaded services:
$ systemctl list-units -all | grep service | grep loaded | awk '{print $1;}'
- List all enabled services:
$ systemctl list-unit-files | grep service | grep enabled | awk '{print $1;}' > enabled.txt
- Find a list of services that are loaded but not enabled:
$ systemctl list-units -all | grep service | grep loaded | awk '{print $1;}' > loaded.txt $ systemctl list-unit-files | grep service | grep enabled | awk '{print $1;}' > enabled.txt $ diff -y loaded.txt enabled.txt # Check for missing ones: $ diff -y loaded.txt enabled.txt | grep '<'
- List failed services:
$ systemctl --failed UNIT LOAD ACTIVE SUB DESCRIPTION ● pollinate.service loaded failed failed Seed the pseudo random number generator on first boot ● vboxadd.service loaded failed failed LSB: VirtualBox Linux Additions kernel modules LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type.
- cgroup tree
$ systemd-cgls ├─1 /sbin/init ├─system.slice │ ├─dbus.service │ │ └─776 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation │ ├─cron.service │ │ └─692 /usr/sbin/cron -f ...
- ps with cgroups:
$ alias psc='ps xawf -eo pid,user,cgroup,args'
- Edit or create a service
$ systemctl edit --force --full my-new.service [Unit] Description=Description of my service After=network-online.target [Service] Type=idle User=bob WorkingDirectory=/path/to ExecStart=/path/to/version1 # Otherwise ExecStart=/path/to/version1 [Install] WantedBy=multi-user.target
Related commands
systemd-analyze
- Analyze system boot-up performance
$ systemd-analyze Startup finished in 5.223s (kernel) + 7.781s (userspace) = 13.004s # ~OR~ $ systemd-analyze # AWS EC2 instance (t2-micro): Startup finished in 1.588s (kernel) + 3.100s (initrd) + 27.516s (userspace) = 32.206s multi-user.target reached after 11.735s in userspace # ~OR~ $ systemd-analyze # System76 laptop running Ubuntu 18.04: Startup finished in 3.993s (firmware) + 29.599s (loader) + 5.337s (kernel) + 12.725s (userspace) = 51.655s graphical.target reached after 12.717s in userspace
- Plot all dependencies of any unit whose name starts with "avahi-daemon":
$ systemd-analyze dot 'avahi-daemon.*' | dot -Tsvg > avahi.svg $ eog avahi.svg
- Plot the dependencies between all known target units:
$ systemd-analyze dot --to-pattern='*.target' --from-pattern='*.target' | dot -Tsvg > targets.svg $ eog targets.svg
journalctl
Note: combine with syslog-ng for backward compatibility.
$ journalctl $ journalctl | grep -Ei 'error|fail' $ journalctl -b # show only logs from this boot $ journalctl -b -1 # show only logs from previous boot $ journalctl -u ssh # show only logs for a given unit $ journalctl -f # follow (somewhat analogous to `tail -f /var/log/messages`) $ journalctl -f -u ssh.service # show only logs for ssh unit and follow
- Show logs for a given date/time period:
$ journalctl -u ssh --since="2014-12-06 23:35:00" $ journalctl --since "2014-12-06" --until "2014-12-07 03:00" $ journalctl --since yesterday $ journalctl --since 03:00 --until "1 hour ago" $ journalctl -u ssh.service --since="5 minutes ago"
- Show BIOS boot up sequence:
$ journalctl --no-hostname -o short-monotonic --boot -0
- Cleanup journal logs (i.e., the self-maintenance method is to vacuum the logs by size or time)
- Retain only the past two days:
$ journalctl --vacuum-time=2d
- Retain only the past 500 MB:
$ journalctl --vacuum-size=500M
For an even more robust cleanup:
$ journalctl --flush --rotate $ journalctl --vacuum-time=1s
You can also use the --since
argument to filter entries:
--since "2017-10-14 17:00:00" --since today
Finally, you can set the following in /etc/systemd/journald.conf
:
SystemMaxUse=100M
- Misc:
$ journalctl --utc -ke
Where:
--utc
: show time in Coordinated Universal Time (UTC).-ke
: show only kernel messages and jumps to end of the log.
See: man journalctl
for more information.
timedatectl
Note: Most of these commands will need to be run as either root or sudo and is only valid for systems using systemd.
- List all available timezones on your computer/server:
$ timedatectl list-timezones
- Set your computer's/server's timezone:
$ timedatectl set-timezone region/timezone
- For instance, to set your timezone to United States Pacific Time (PST; -8GMT):
$ timedatectl set-timezone America/Vancouver
Your system will be updated to use the selected timezone. You can verify with:
$ timedatectl
Local time: Fri, 2012-11-02 09:26:46 CET Universal time: Fri, 2012-11-02 08:26:46 UTC RTC time: Fri, 2012-11-02 08:26:45 Timezone: Europe/Warsaw UTC offset: +0100 NTP enabled: no NTP synchronized: no RTC in local TZ: no DST active: no Last DST change: CEST → CET, DST became inactive Sun, 2012-10-28 02:59:59 CEST Sun, 2012-10-28 02:00:00 CET Next DST change: CET → CEST, DST will become active the clock will jump one hour forward Sun, 2013-03-31 01:59:59 CET Sun, 2013-03-31 03:00:00 CEST
- Enable an NTP daemon (chronyd):
$ timedatectl set-ntp true ==== AUTHENTICATING FOR org.freedesktop.timedate1.set-ntp === Authentication is required to control whether network time synchronization shall be enabled. Authenticating as: user Password: ******** ==== AUTHENTICATION COMPLETE === $ systemctl status chronyd.service chronyd.service - NTP client/server Loaded: loaded (/lib/systemd/system/chronyd.service; enabled) Active: active (running) since Fri, 2012-11-02 09:36:25 CET; 5s ago ...
hostnamectl
`hostnamectl`
allows you to control the system hostname
.
- Example response from a laptop running Ubuntu:
$ hostnamectl
Static hostname: my_hostname Icon name: computer-laptop Chassis: laptop Boot ID: ffffffffffffffffffffffffffffffff Operating System: Ubuntu 14.04.2 LTS Kernel: Linux 3.13.0-52-generic Architecture: x86_64
- Example response from a vagrant box running Fedora:
$ hostnamectl
Static hostname: localhost.localdomain Icon name: computer-vm Chassis: vm Machine ID: ffffffffffffffffffffffffffffffff Boot ID: ffffffffffffffffffffffffffffffff Virtualization: oracle Operating System: Fedora 22 (Twenty Two) CPE OS Name: cpe:/o:fedoraproject:fedora:22 Kernel: Linux 4.0.4-303.fc22.x86_64 Architecture: x86-64
- Example response from an AWS EC2 instance running CentOS 7:
$ hostnamectl
Static hostname: ip-172-22-1-210.us-west-2.compute.internal Transient hostname: ip-172-22-1-210 Icon name: computer-vm Chassis: vm Machine ID: f32e0af35337b5dfcbedcb0d1de8dca1 Boot ID: ea5461881a264a88abe239b2337169bf Virtualization: xen Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe:/o:centos:centos:7 Kernel: Linux 3.10.0-327.10.1.el7.x86_64 Architecture: x86-64
- Change the hostname:
$ sudo hostnamectl set-hostname <new-hostname> $ vi /etc/hosts 127.0.0.1 localhost 127.0.1.1 <new-hostname>
- Other ways to change the hostname:
$ sudo hostnamectl --transient set-hostname $hostname $ sudo hostnamectl --static set-hostname $hostname $ sudo hostnamectl --pretty set-hostname $hostname
Systemd timers
- List all timers on current host:
$ systemctl status *timer ● apt-daily.timer - Daily apt download activities Loaded: loaded (/lib/systemd/system/apt-daily.timer; enabled; vendor preset: enabled) Active: active (waiting) since Sun 2021-08-08 04:57:00 PDT; 1 weeks 2 days ago Trigger: Wed 2021-08-18 04:19:59 PDT; 14h left ...
- Check status of a given timer:
$ systemctl status motd-news.timer ● motd-news.timer - Message of the Day Loaded: loaded (/lib/systemd/system/motd-news.timer; enabled; vendor preset: enabled) Active: active (waiting) since Sun 2021-08-08 04:57:00 PDT; 1 weeks 2 days ago Trigger: Wed 2021-08-18 04:44:11 PDT; 14h left
- Check the journal for a given timer:
$ journalctl -S today -u apt-daily-upgrade.timer -- Logs begin at Fri 2018-07-13 11:54:18 PDT, end at Tue 2021-08-17 14:20:37 PDT. -- -- No entries --
- Useful for setting timers:
$ systemd-analyze calendar 2030-08-17 Original form: 2030-08-17 Normalized form: 2030-08-17 00:00:00 Next elapse: Sat 2030-08-17 00:00:00 PDT (in UTC): Sat 2030-08-17 07:00:00 UTC From now: 8 years 11 months left $ systemd-analyze calendar 2030-08-17 20:10:12 Original form: 2030-08-17 Normalized form: 2030-08-17 00:00:00 Next elapse: Sat 2030-08-17 00:00:00 PDT (in UTC): Sat 2030-08-17 07:00:00 UTC From now: 8 years 11 months left Original form: 20:10:12 Normalized form: *-*-* 20:10:12 Next elapse: Tue 2021-08-17 20:10:12 PDT (in UTC): Wed 2021-08-18 03:10:12 UTC From now: 5h 46min left
Other
See: for a complete list
- Control the system locale and keyboard layout settings:
$ localectl System Locale: LANG=en_US.UTF-8 VC Keymap: n/a X11 Layout: us X11 Model: pc105
$ loginctl # Control the systemd login manager $ busctl # Introspect the bus $ machinectl # Control the systemd machine manager $ networkctl # Query the status of network links $ systemd-cgls # Recursively show control group contents $ systemd-cgtop # Show top control groups by their resource usage $ systemd-path # List and query system and user paths
- List content of an initramfs image:
$ lsinitramfs /boot/initrd.img-$(uname -r) | less
External links
- Official website
- Full systemd documentation can be found by running
man 5 systemd.unit
- How To Use Journalctl to View and Manipulate Systemd Logs
- Explanation of `machinectl` — the `su` replacement on systemd