10-Systemd.md

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Systemd

---

References

https://www.freedesktop.org/software/systemd/man/systemctl.html
https://access.redhat.com/attachments/12052018_systemd_6.pdf
https://access.redhat.com/documentation/

• Manage services and units

  https://www.digitalocean.com/community/tutorials/

  sudo systemctl status application.service

  sudo systemctl start application.service
  sudo systemctl stop application.service
  

  sudo systemctl enable application.service
  sudo systemctl disable application.service
  

  sudo systemctl restart application.service
  sudo systemctl reload application.service
  

  sudo systemctl daemon-reload

• Modify unit file

  https://serverfault.com/questions/840996/

  systemctl edit <service-name>

• List services

  https://askubuntu.com/questions/795226/

  systemctl list-unit-files --type=service
  systemctl list-unit-files | grep "enabled "
  systemctl list-units --no-pager
  systemctl | grep running
  

• List timers

  systemctl list-timers --all
  

Log files

https://www.golinuxcloud.com/view-logs-using-journalctl-filt

• journalctl

  last 100 lines : journalctl -b -f --lines=100

  last errors : journalctl --no-pager -b -p 4

  last errors : journalctl --no-pager -b -p err

• Read shutdown log

  journalctl -b -1 -e

• Rotation des logs avec logrotate

  https://journaldunadminlinux.fr/rotation-des-logs-avec-logro

• Delete old files

  https://unix.stackexchange.com/questions/459996/
  https://unix.stackexchange.com/questions/184488/

  sudo find /var/log -type f -mtime +5 -delete
  sudo find /var/log -maxdepth 1 -type f -mtime +5 -delete
  sudo find /var/log ! -wholename "/var/log/journal/*" -type f -mtime +5 -delete
  

Turn off excessive logging

• sudo

  https://unix.stackexchange.com/questions/224370/
  https://unix.stackexchange.com/questions/637227/

  In /etc/pam.d/sudo add the following with a real user name :

  session [success=1 default=ignore] pam_succeed_if.so quiet uid = 0 ruser = <username>

  Example of /etc/pam.d/sudo file :

  #%PAM-1.0
  
  # Set up user limits from /etc/security/limits.conf.
  session    required   pam_limits.so
  session [success=1 default=ignore] pam_succeed_if.so quiet uid = 0 ruser = hotnuma
  
  @include common-auth
  @include common-account
  @include common-session-noninteractive
  

• rtkit-daemon

  https://unix.stackexchange.com/questions/684379/

  sudo mkdir /etc/systemd/system/rtkit-daemon.service.d/
  sudo geany /etc/systemd/system/rtkit-daemon.service.d/log.conf
  

  Add the following :

  [Service]
  LogLevelMax=4
  

  Reload the service

  sudo systemctl daemon-reload
  sudo systemctl restart rtkit-daemon.service
  

Other

• Analyze startup

  systemd-analyze time
  systemd-analyze --no-pager blame
  systemd-analyze critical-chain