Latest revision as of 16:30, 21 November 2024

Documentation

Locations

/etc/systemd
/usr/lib/systemd/
/lib/systemd

HOWTO

systemctl verbose

SYSTEMD_LOG_LEVEL=debug systemctl start yourservice

Services

List enabled services

See https://www.baeldung.com/linux/systemctl-list-enabled-services

systemctl list-unit-files --state=enabled

Edit systemd service file

systemctl edit --full my.service

Timers

https://opensource.com/article/20/7/systemd-timers
https://wiki.archlinux.org/title/Systemd/Timers
https://linuxhint.com/cron_systemd_timer/ also about random time

man systemd.timer

List active timers

systemctl list-timers

List all timers

systemctl list-timers --all

Enable timer

systemctl enable fstrim.timer

Auto restart crashed services

systemctl edit elasticsearch.service

add:

[Service]
Restart=always

then

systemctl daemon-reload
systemctl restart elasticsearch.service

And to get an email when service gets restarted: https://dev.to/setevoy/linux-systemd-unit-files-edit-restart-on-failure-and-email-notifications-5h3k

Logs

View systemd logs

journalctl -u postfix

FAQ

Analyze boot processes

systemd-analyze blame

gateway4 has been deprecated

Using routes:

routes:
- to: default
  via: 192.168.1.1

Systemd and DNS

resolvectl status

Change nameserversers resolvectl uses

On Ubuntu

Edit the netplan file

netplan generate
netplan apply

Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found.

Means systemd-resolved is not running

Restart:

systemctl restart systemd-resolved

Add nameserver

Sacrifice a chicken

Flush caches

thing from the past?

systemd-resolve --flush-caches

All status

systemctl status -a

syslog spam

https://psyq123.wordpress.com/2015/06/29/if-you-get-a-lot-of-logspam-from-systemd-in-your-varlogsyslog-this-might-help/

list available services

systemctl list-unit-files

or

systemctl list-units

normal interface names

net.ifnames=0

Show failed services

systemctl --failed

systemd: Started Session

Change loglevel to notice in /etc/systemd/system.conf

systemctl daemon-reexec

Status

Active: inactive (dead)

parameter ActiveState would return inactive

SubState returns dead

@@ Line 1: / Line 1: @@
 &nbsp;
 = Documentation =
@@ Line 15: / Line 16: @@
 *[[https://blog.darknedgy.net/technology/2020/05/02/0/index.html#tech-critique https://blog.darknedgy.net/technology/2020/05/02/0/index.html#tech-critique]
 *[https://mohsensy.github.io/sysadmin/2018/08/19/systemd-service-tutorial.html Systemd service tutorial]
+*[https://www.freedesktop.org/wiki/Software/systemd/dbus/ https://www.freedesktop.org/wiki/Software/systemd/dbus/ Systemd and dbus]
-([https://www.thegeekdiary.com/how-to-boot-into-rescue-mode-or-emergency-mode-through-systemd-in-centos-rhel-7-and-8/ Single user/emergency]
+*[https://www.thegeekdiary.com/how-to-boot-into-rescue-mode-or-emergency-mode-through-systemd-in-centos-rhel-7-and-8/ Single user/emergency]
 = Locations =
@@ Line 28: / Line 29: @@
 = HOWTO =
+==systemctl verbose==
+ SYSTEMD_LOG_LEVEL=debug systemctl start yourservice
+==Services==
+===List enabled services===
+See https://www.baeldung.com/linux/systemctl-list-enabled-services
+ systemctl list-unit-files --state=enabled
+===Edit systemd service file===
+ systemctl edit --full my.service
 == Timers ==
@@ Line 33: / Line 45: @@
 *[https://opensource.com/article/20/7/systemd-timers https://opensource.com/article/20/7/systemd-timers]
 *[https://wiki.archlinux.org/title/Systemd/Timers https://wiki.archlinux.org/title/Systemd/Timers]
+*https://linuxhint.com/cron_systemd_timer/ also about random time
   man systemd.timer
@@ Line 45: / Line 57: @@
   systemctl list-timers --all
-=== Create timer ===
+=== Enable timer ===
   systemctl enable fstrim.timer
+== Auto restart crashed services ==
+ systemctl edit elasticsearch.service
+add:
+ [Service]
+ Restart=always
+then
+ systemctl daemon-reload
+ systemctl restart elasticsearch.service
+And to get an email when service gets restarted: https://dev.to/setevoy/linux-systemd-unit-files-edit-restart-on-failure-and-email-notifications-5h3k
+==Logs==
+===View systemd logs===
+ journalctl -u postfix
 = FAQ =
-==Fix journal size==
- journalctl --vacuum-time=10d
-or
- journalctl --vacuum-size=1G
 == Analyze boot processes ==
@@ Line 61: / Line 84: @@
   systemd-analyze blame
-&nbsp;
+== gateway4 has been deprecated ==
+Using routes:
-&nbsp;
+ routes:
+ - to: default
+   via: 192.168.1.1
 == Systemd and DNS ==
   resolvectl status
+===Change nameserversers resolvectl uses===
+====On Ubuntu====
+Edit the netplan file
+ netplan generate
+ netplan apply
+=== Failed to get global data: Unit dbus-org.freedesktop.resolve1.service not found. ===
+Means systemd-resolved is not running
 Restart:
@@ Line 74: / Line 110: @@
+&nbsp;
 === Add nameserver ===
@@ Line 82: / Line 120: @@
 === Flush caches ===
+# thing from the past?
   systemd-resolve --flush-caches
@@ Line 118: / Line 156: @@
   systemctl daemon-reexec
+==Status==
+=== Active: inactive (dead) ===
+parameter ActiveState would return inactive
+SubState returns dead

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