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Sample crontab job - checking system clock
Services and Regular Jobs example from a Well House Consultants training course
More on Services and Regular Jobs [link]
Source code: timeset Module: A164
#!/usr/bin/env perl
# Crontab job for root to set clock from remote host # 3 3 * * * /home/wellho/serverstatus/timeset use LWP; $ua = LWP::UserAgent->new(agent => "System Monitor http://wellho.info/3015"); $resp = $ua->get("http://wellho.net/time.php"); if (($status = $resp->code()) != 200) { print ("$0 response code $status\n"); exit(); } $remote = $resp->decoded_content; $local = time(); $offset = abs($remote - $local); if ($offset > 120) { print ("$0 major clock change requested $remote $local $offset\n"); exit(); } @time = localtime($remote); $time[5]+=1900; $time[4]++; $newset = sprintf("%04d%02d%02d %02d:%02d:%02d",@time[5,4,3,2,1,0]); # date --set="20130331 09:25" if (-t STDIN or $> > 0) { print ("date set. From Crontab as root will run\n"); print ("`date --set='$newset'`\n"); print ("Clock change requested $remote $local (by $offset seconds)\n"); } else { `date --set='$newset'`; } __END__ -bash-4.1$ perl timeset date set. From Crontab as root will run `date --set='20130331 10:06:08'` Clock change requested 1364720768 1364720712 (by 56 seconds) -bash-4.1$ date Sun Mar 31 10:05:51 BST 2013 -bash-4.1$ Learn about this subject
This module and example are covered on the following public courses:
* Deploying LAMP - Linux, Apache, MySQL, Perl/PHP * Linux Administration * Deploying Java Applications on Linux / Unix * Linux bootcamp Also available on on site courses for larger groups Books covering this topic
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covering Lamp deployment are listed here and when you've selected a
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Other Examples
This example comes from our "Services and Regular Jobs" training module. You'll find a description of the topic and some
other closely related examples on the "Services and Regular Jobs" module index page.
Full description of the source code
The complete training module that describes this source code
is availble for download (for limited use) from
our download centre.
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