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Script to detect time drift

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# 9  
The following is even simpler, because sed simply strips a leading - and a trailing .xxx.
This would even run in bash or dash.
ntpq -c rl | sed -n '
if [[ -z $offset ]]
  echo "no offset, check NTP service with ntpq -pn"
elif [[ $offset -gt 50 ]]
  echo "$offset is greater than 50 msec"

Last edited by MadeInGermany; 05-16-2018 at 03:29 PM.. Reason: added check for empty return value
# 10  
Hi MadeInGermany,

Quick question for my knowledge purposes.
If NTP is scheduled to run every 10 minutes on the server, do you think the clocks get synchronised?
Will there be an explicit need to check for the time drifts? Can the time drift situation occur at all?

Thank you.
# 11  
This ntpq is a measurement.
If you trust your NTP setup then you do not need a measurement.

BTW I just have changed my last post, added another check for the case that NTP service does not work (somebody stopped it, all time peers are unreachable, ...).

With HP-UX 11.23 I remember a strangeness: ntpq reported sudden time jumps and the monitoring got occasional alerts.
No such issues on AIX, Solaris, Linux.

driftfile is not relevant. This is the drift between the hardware clock and the NTP servers., that predicts the real drift in case the time peers would not be reachable. Effectively it only causes a faster time sync after a startup of the NTP service. One can run NTP without a driftfile.

Last edited by MadeInGermany; 05-16-2018 at 03:39 PM..
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# 13  

One more question.
Once we detect the offset >+/- 50ms, can we correct the time within the script i.e. get the time in sync ?


Last edited by Green_Star; 05-23-2018 at 12:36 PM..
# 14  
No, this is monitoring. Once monitoring detects an offset you must do a root cause analysis why your sync mechanism has failed.
Your sync mechanism:
ensure there is either ntpd running (needs a correctly configured ntp.conf, check with ntpq -pn) or a cron job with ntpdate.
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