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INFO | Time and date

Command/ToolDescriptionInstructions
timedatectl


** systemd-based OS		Management of system time and time zone. Enable systemd-timesyncd.– Show current time: timedatectl – Change time zone: timedatectl set-timezone Europe/Berlin – Activate synchronization: timedatectl set-ntp true
systemctl


** systemd-based OS		Control of the time service systemd-timesyncd.– Check status: systemctl status systemd-timesyncd – Start: systemctl start systemd-timesyncd – Enable: systemctl enable systemd-timesyncd
chronyd


** Ubuntu, Debian, RHEL, CentOS		Alternative time service, precise and resource-saving.– Installation: sudo apt install chrony – Configuration: /etc/chrony/chrony.conf edit – Start service: sudo systemctl start chronyd
ntpd


** Ubuntu, Debian		Classic time service for synchronization with NTP servers.– Installation: sudo apt install ntp – Configuration: /etc/ntp.conf edit – Start service: sudo systemctl start ntp
hwclock


** AllLinux distributions		Setting the hardware time (BIOS).– Read time: hwclock –show – Set time: hwclock –set –date=”2024-11-24 10:00:00″ – Write time to system clock: hwclock –hctosys
Date


** AllLinux distributions		Direct setting and display of the system time (less common).– Show time: date – Set time: date –set “2024-11-24 10:00:00”
ntpq

** Ubuntu, Debian		NTP synchronization status check.– View Connected Servers: ntpq -p
/etc/systemd/timesyncd.conf


** systemd-based OS		Configuration of the systemd-timesyncd.– Enter NTP server: NTP=pool.ntp.org – Restart service: sudo systemctl restart systemd-timesyncd

Ubuntu/Debian with timedatectl

  • Check current time:
    timedatectl
  • Set time zone:
    sudo timedatectl set-timezone Europe/Berlin
  • To enable NTP synchronization:
    sudo timedatectl set-ntp true
  • Check status:
    Timedatectl

RHEL/CentOS with chronyd

  • Installation:
    sudo yum install chrony
  • Configuration:
    • Open file /etc/chrony.conf:
      sudo nano /etc/chrony.conf
    • To add NTP servers:
      Server pool.ntp.org iburst
  • Start and activate the service:
    sudo systemctl start chronyd
    sudo systemctl enable chronyd

How to Use ntpd on Ubuntu

  • Installation:
    sudo apt install ntp
  • Configuration:
    • Open the /etc/ntp.conf file:
      sudo nano /etc/ntp.conf
    • To add NTP servers:
      Server pool.ntp.org
  • Start service:
    sudo systemctl start ntp

Synchronize hardware clock

  • Synchronize time from system clock to hardware clock:
    sudo hwclock –systohc
  • Display hardware time:
    hwclock –show