Linux timedatectl, hwclock & Timezone Commands

Linux keeps time in more than one place, and the commands that show it are easy to confuse. The system clock is what programs see; the
hardware clock (RTC) keeps time while the machine is off; the timezone only changes how time is displayed. This guide covers each command and when to use it.

For keeping the clock accurate over a network, continue with the chrony NTP guide; if sync fails, see the
troubleshooting checklist.

Understand the Three Concepts

System clock, hardware clock and timezone are separate. Changing the timezone never changes the actual moment in time; it only changes the label.

architectureclocks.txt

  hardware clock (RTC) --boot--> system clock --display--> timezone --> what you read
  NTP (chrony) disciplines the system clock; rtcsync keeps the RTC aligned

System clock, RTC and timezone — Three separate concepts

Read Everything with timedatectl

One command summarises local time, UTC, RTC time, timezone and sync state.

bashstatus

timedatectl
timedatectl show --property=Timezone --property=NTPSynchronized

timedatectl status — Local, UTC, RTC, sync

Set the Timezone

Find the exact name, then set it. Names follow the Region/City pattern.

bashtimezone

timedatectl list-timezones | grep -i kolkata
sudo timedatectl set-timezone Asia/Kolkata
date

Setting the timezone — List, set, verify

Turn On Network Time

set-ntp true enables network time synchronisation through the configured time service. It needs a service to do the work, such as chrony or systemd-timesyncd.

bashenable and check

sudo timedatectl set-ntp true
timedatectl | grep -E 'NTP|synchronized'

NoteIf a full NTP daemon such as chrony is running, its own tools (chronyc tracking) give the authoritative picture.

Set the Time by Hand

Manual time is only accepted while NTP is off, so turn it off, set the time, and turn it back on.

bashmanual set

sudo timedatectl set-ntp false
sudo timedatectl set-time '2026-09-21 14:30:00'
sudo timedatectl set-ntp true

Sync the Hardware Clock with hwclock

hwclock reads and writes the RTC. Use --systohc after fixing the system clock, and --hctosys to load the RTC into the system clock.

bashhwclock

sudo hwclock --show
sudo hwclock --systohc
sudo hwclock --hctosys

Keep the RTC in UTC (Usually)

Linux normally stores UTC in the RTC. Windows expects local time, which causes wrong clocks on dual-boot machines. Choose one convention; UTC is the better default for servers.

bashcheck and set

timedatectl | grep 'RTC in local TZ'
sudo timedatectl set-local-rtc 0

Format Dates for Scripts

date formats are the everyday tool for log lines, file names and backups (see our shell scripting guide).

bashexamples

date -u +%Y-%m-%dT%H:%M:%SZ
date +%F_%H%M
date -d 'yesterday' +%F
date -d '2 hours ago' +%T

date formats — UTC, stamps, relative dates

Quick Reference

timedatectl to read/set zone and NTP; hwclock --systohc after fixing the clock
Keep the RTC in UTC on servers; use date -u in scripts

Linux Time and Timezone Commands: timedatectl, hwclock and date Explained