How do I retrieve the date from the Internet and set my computer's clock, from the command line?
You can use :
sudo dpkg-reconfigure tzdata
for configuring your timezone .
For updating time and date from internet use the following :
If ntpd is not installed use any one of the following command to install ntpd:
For RPM based:
yum install ntp
For Debian based:
sudo apt-get install ntp
You should at least set following parameter in /etc/ntp.conf config file: server
For example, open /etc/ntp.conf file using vi text editor:
# vi /etc/ntp.conf
Locate server parameter and set it as follows:
Save the file and restart the ntpd service:
# /etc/init.d/ntpd start
You can synchronize the system clock to an NTP server immediately with following command:
# ntpdate pool.ntp.org
*For setting the time and date manually use the following syntax:
For example, set new data to 2 Oct 2006 18:00:00, type the following command as root user:
# date -s "2 OCT 2006 18:00:00"
# date --set="2 OCT 2006 18:00:00"
You can also simplify format using following syntax:
# date +%Y%m%d -s "20081128"
To set time use the following syntax:
# date +%T -s "10:13:13"
10: Hour (hh) 13: Minute (mm) 13: Second (ss)
Use %p locale’s equivalent of either AM or PM, enter:
# date +%T%p -s "6:10:30AM" # date +%T%p -s "12:10:30PM"
A small code I found to update your time in case you don't want to install anything just to update the date. :)
sudo date -s "$(wget -qSO- --max-redirect=0 google.com 2>&1 | grep Date: | cut -d' ' -f5-8)Z"
I use this:
sudo ntpd -qg; sudo hwclock -w
first tell ntpd to just set the time and stop after that with -q. Also, in case a your clock has a big error we need to tell ntpd to also adjust in that case with -g. Finally write the clock to hardware to preserve the changes when rebooting with hwclock -w (-w for setting hardwareclock to current system time, there is a difference).
Use ntpdate, ntpd, or Chrony to connect to a NTP server.
Some distributions are shipping rdate for that purpose. Basic usage:
# just query bash-4.2$ rdate pool.ntp.org rdate: [pool.ntp.org] Wed Jun 12 11:05:40 2013 # set system time bash-4.2$ rdate -s pool.ntp.org
After some research, I ended up with this. I also applied it to my own server:
sudo apt-get install ntp sudo dpkg-reconfigure ntp ntpq -p
If the last command shows a valid list of servers, you are good to go. The command will run a quite complex set of algorithms which will iterate your clock drift, among other things, and compensate for them. You will end up with a pretty accurate clock even if you lose the connection to the NTP servers. However, the command does require a few minutes to get started.
To find "peers" (hosts you can query) you can use
If you already have an NTP service running you have to stop it before manually updating, for example using
sudo service ntp stop.
Now you can query a peer, for example using
sudo ntpdate "peer".
Using rdate tool as suggested in manatwork's answer, but with SNTP protocol
-n and IPv4
-4 options on:
# just print synced time, not set rdate -n -4 -p time-a.nist.gov # print and set synced time sudo rdate -n -4 time-a.nist.gov
The tool may be installed on Debian this way:
sudo apt-get install rdate
In addition to Tushar's reply, I also had to do
apt-get install ntpdate on my Ubuntu 14.04.
Posting as answer because reputation does not suffice for commenting.
I also was looking for a non ntp/ntpd way of resetting clock periodically. I liked the google.com header parsing but found it did not work on ubuntu. I think this will also work on a Raspberry Pi.
sudo date +"%d %b %Y %T %Z" -s "$(wget -qSO- --max-redirect=0 http://google.com 2>&1 | grep '^ Date:' | cut -d' ' -f 5-)"
Also an alternative using curl instead of wget.
sudo date +"%d %b %Y %T %Z" -s "$(curl -s --head http://google.com | grep '^Date:' | cut -d' ' -f 3-)"
Tested on PI with Cellular Network and results are similar:
Using host & wget -- RCV: 1324 bytes SND: 581 bytes Using host & curl -- RCV: 1318 bytes SND: 567 bytes
Note I use host to resolve google.com to an IP address so I can open only that IP for duration of this command with iptables.