Show system time:

1date

Show hardware time:

1sudo hwclock -r

Change system time to match hardware time:

1sudo hwclock --hctosys

Change hardware time to match system time:

1sudo hwclock --systohc

Manually set the hardware time to a specified date:

1sudo hwclock --set --date="8/25/19 13:30:00"

Normal Date

1date +%d/%m/%y

Unix Time

Computers started counting time on January 1st, 1970, and added one second-per-second. If your clock shows you're in the 70's, it's reset to the start.

Track the time in Unix-time:

1date +%s

Network Time Providers

Servers which take their time from an observatory we call Stratum 1 servers. Servers which takes their time from Stratum n servers are Stratum n+1 servers.

Install ntp with:

1sudo apt-get install -y ntp

The shell command for this is ntpq. Monitor the service providers using:

1ntpq -p