Determine the time difference between two linux servers
ntpdate -q does what you want.
Example:
root@host1:~# ntpdate -q host2
server host2, stratum 4, offset 109.584520, delay 0.77560
17 Apr 21:48:16 ntpdate[28849]: no server suitable for synchronization found
In this case, the servers have a difference of about 110 seconds.
If the two servers are NTP peers, use
ntpq -p
Which will show current offsets
Note that NTP takes into account network latency. If you know each server's offset from a common NTP server, that is about as accurate as you can get using standard tools.
I have two unix servers using NTP. Lets see what sort of time they are keeping:
$ sudo /usr/sbin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
hufu.ki.iif.hu 185.219.2.214 2 u 12 64 1 71.755 -0.073 0.001
web.puflet.info 188.138.107.156 3 u 11 64 1 78.248 0.417 0.001
84.2.44.19 10.20.75.140 2 u 10 64 1 74.721 -1.076 0.001
$ sudo /usr/sbin/ntpq -p otherbox
remote refid st t when poll reach delay offset jitter
==============================================================================
+ntp2.exa-networ 195.66.241.10 2 u 799 1024 377 43.405 7.796 218.471
+mantaray.netine 249.240.53.144 3 u 289 1024 377 34.782 8.484 212.631
*rilynn.me.uk 81.2.117.228 2 u 765 1024 377 45.665 6.804 142.023
+ntp.thirdlight. 193.67.79.202 2 u 791 1024 377 38.322 9.871 223.397
They are using different servers because they use servers from the ntp pool.
I'll temporarily add otherbox to this server's config so I can directly measure the time offset
$ sudo vi /etc/ntp.conf
(added `server otherbox`)
$ sudo /sbin/service ntpd restart
$ sudo /usr/sbin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
gamma.h3x.no 78.70.33.22 3 u 4 64 1 34.840 -0.964 0.001
web.puflet.info 188.138.107.156 3 u 3 64 1 78.148 -1.243 0.001
alpha.rueckgr.a 129.69.1.153 2 u 2 64 1 61.495 -2.362 0.001
otherbox.exampl 60.155.73.34 3 u 1 64 1 0.604 -11.286 0.001
It looks like timestamps on my two servers are about 11 ms different.
You can also do the following on host1:
root@host1# clockdiff -o host2