Today (Saturday) We will make some minor tuning adjustments to MySQL.

You may experience 2 up to 10 seconds "glitch time" when we restart MySQL. We expect to make these adjustments around 1AM Eastern Daylight Saving Time (EDT) US.


Script to detect time drift


Login or Register to Reply

 
Thread Tools Search this Thread
# 9  
The following is even simpler, because sed simply strips a leading - and a trailing .xxx.
This would even run in bash or dash.
Code:
#!/bin/ksh
PATH=/bin:/usr/bin:/usr/sbin:/sbin
offset=$(
ntpq -c rl | sed -n '
s/.*phase=-\{0,1\}\([0-9]*\).*/\1/p
t
s/.*offset=-\{0,1\}\([0-9]*\).*/\1/p
'
)
if [[ -z $offset ]]
then
  echo "no offset, check NTP service with ntpq -pn"
elif [[ $offset -gt 50 ]]
then
  echo "$offset is greater than 50 msec"
fi


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..
This User Gave Thanks to MadeInGermany For This Post:
# 13  
Hello,

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

Thanks!

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.
This User Gave Thanks to MadeInGermany For This Post:
Login or Register to Reply

|
Thread Tools Search this Thread
Search this Thread:
Advanced Search

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to detect url in use in a script?

Hello, I have a small script and it runs from web application in below format: pipe:///path_to_myscript.sh url1 url2 url3 myscript.sh: #!/bin/bash count=0 while do count=$((count+1)) exec 3>&1 ((ffmpeg -i $1 ...... -f mpegts pipe:1 2>/dev/null 1>&3 ) 2>&1 | \ while read LINE; do echo... (9 Replies)
Discussion started by: baris35
9 Replies

2. UNIX for Beginners Questions & Answers

Script to detect time drift on server

Hello there, I am not an expert in networking related stuff but I got a requirement to create UNIX script to query our Company's internal time source via NTP for time drift detect and report it when > +/- 50ms. I have been googling a lot but thought to post it in this forum to get a... (1 Reply)
Discussion started by: Green_Star
1 Replies

3. UNIX for Advanced & Expert Users

A script to detect system type

Hi forum, So I am trying to determine the OS type with the following script: #!/usr/bin/sh OStype1=`uname -s` Sunos1=SunOs if then echo "This system is Linux" exit 0 elif then echo "This system is SunOs" exit 0 elif (1 Reply)
Discussion started by: dampio
1 Replies

4. Shell Programming and Scripting

Help with detect with regex and move script

Hi all, I am needing some help with a script that will search for a video file by known extensions and then do a pattern search (I'm guessing via regex) and then based on a match of one type of another move the file to an assigned directory. I would like to do this with either a shell script... (7 Replies)
Discussion started by: Simplify
7 Replies

5. Shell Programming and Scripting

Detect current shell inside a script

I wish to print my current shell which happens to be bash in my script check.sh more check.sh echo $0 echo `ps -p $$` But instead of printing it prints check.sh i.e the name of the script for both the commands. Can you please suggest how to print the current shell i m on inside the... (2 Replies)
Discussion started by: mohtashims
2 Replies

6. Shell Programming and Scripting

Bash script to detect nonpingable hosts

I have a script to detect if a host is pingable or not. The problem is that I would like it to put the nonpingable hosts in one file and the pingable hosts in another. I have come up with this so far: for ip in `cat /tmp/testlist2`; do ping -c 3 $ip >/dev/null && echo "$ip is up" || echo "$ip... (5 Replies)
Discussion started by: newbie2010
5 Replies

7. Shell Programming and Scripting

Detect if script starts from queue

Dear community, what I'm try to do is deny users to run a script without parameters from command bash, but the same script should run without parameters only from crontab. Example runs by crontab:*/5 * * * * /tmp/script.sh Here the normal execution starts every 5 minutes Example #1 runs by... (16 Replies)
Discussion started by: Lord Spectre
16 Replies

8. Shell Programming and Scripting

AWK script to detect webpages from file

Hi guys I'm very new to unix and I have to create an awk script that detects webpage addresses from a file/webpage and outputs how many times each webpage was detected.e.g. if my file was: (Note: The symbol " was added to stop them being created into links) "www.google.com"... (1 Reply)
Discussion started by: ROFL
1 Replies

9. UNIX for Dummies Questions & Answers

how to detect my script is already running

I have a script which must not be run more than once at any given time. THis script will be scheduled to run every 20 mins as a cron job. In my script can i have logic to say if this script is already running from the previous cron, then exit. How do i go about doing that. If you describe the... (11 Replies)
Discussion started by: rmulchandani
11 Replies

Featured Tech Videos