From: Rob Biedenharn <Rob@...>
Date: 2010-12-15T00:21:31+09:00
Subject: Re: Grep a string


On Dec 14, 2010, at 8:32 AM, Rajesh M. wrote:

> Hi list,
>
> I need to grep the entire string "sync; sync; reboot" after 0 10 * * 0
> in crontab -l and store it in a variable, that string is different on
> different systems.
>
>
>
> crontab -l |egrep -i "(sync|reb|shut)"
>
> 0 10 * * 0 sync; sync; reboot <---- regex should look for only sync;
> sync; reboot
>
> cd /var/log
> grep "sync; sync; reboot" cron* |head -1
> cron:Dec 12 10:00:00 hostname CROND[14898]: (root) CMD (sync; sync;
> reboot)
>
> Regular expression should find any string without the digitals (0 10  
> * *
> 0)
>
> For example in another system if the crontab entry is like:
> 0 6 * * 0 shutdown -y -g0 -i6
> regular expression should only look for the string after digitals 0  
> 6 *
> * 0, here it should look for shutdown -y -g0 -i6
>
>
> Please help.
> Thanks in advance

Well, you asked on a Ruby list so you're getting a Ruby answer from me.

crontab -l | ruby -nle 'next if $_ =~ /^\s*#/; fields = $_.split(" ", 
6); puts fields.inspect;'

For your sample, I'll show the output from `echo "0 10 * * 0 sync;  
sync; reboot"` rather than `crontab -l`

$ echo "0 10 * * 0 sync; sync; reboot" | ruby -nle 'next if $_ =~ /^ 
\s*#/; fields = $_.split(" ",6); puts fields.inspect;'
["0", "10", "*", "*", "0", "sync; sync; reboot"]

You could change the first statement from:
	next if $_ =~ /^\s*#/;
which skips comment lines, to something like:
	next unless $_ =~ /sync|reb|shut/;
to only operate on those lines.

-Rob

Rob Biedenharn		
Rob@AgileConsultingLLC.com	http://AgileConsultingLLC.com/
rab@GaslightSoftware.com		http://GaslightSoftware.com/