Run a script automatically in every 2 sec.

[ShibuThomas]

Hi Ricks,
I tried the following.Its working fine.
But instead of rsync we are using unison.
when i tried to use unison.it is not working
The only change i made is

nohup unison $WATCHPT/$FNAME remotemachine:$WATCHPT/ \
	 >>/dev/null 2>&1 &	

unison is installed in my pc.and i checked this unison working.that was 
fine.but with above code it is not working for me.
can you please help me.

Regrads
shibuthomas
Rick Stevens wrote:
> On 06/29/2011 12:08 AM, ShibuThomas wrote:
>   
>> Hi ricks,
>>
>> I wrote a one shell script which contains code for synchronize files
>> between two machines.I want to execute this script every 2 second.How
>> can I do this?.When I gone through net found that usually cron job is
>> used for doing same.But the minimum time frame in cron is 1 minitues.One
>> method is to keep a loop inside my script and execute it.But I would
>> like to know is there any other way to do the same.
>> So how can execute my script every 2 second.Please provide some example
>> code.
>>     
>
> Good lord!  Every 2 seconds?  That's a bit extreme.
>
> Yes, the minimum granularity for a cron job is 1 minute.  If you need
> finer granularity, you need to run a script that does a sleep call:
>
> 	#!/bin/bash
> 	while /bin/true; do
> 	    rsync (or whatever) >/dev/null 2>&1
> 	    sleep 2
> 	done
>
> This will do the rsync command (discarding any messages), wait for
> two seconds, then repeat.
>
> I really, REALLY recommend you do NOT do this as it can be a massive
> resource hog.  If the two machines are on the same LAN, the best bet is
> to share the target directory between them using NFS rather than doing
> some sync job.
>
> Alternately, look at the inotifywait stuff. You can put a watch on a
> directory on the source machine and only launch the sync if a file is
> written in it. You'd need to "yum install inotify-tools", and here's an
> example script:
>
> ------------------------------- CUT HERE -----------------------------
> #!/bin/bash
> # Filename:	watchuploads.sh
> # Author:	Rick Stevens, AllDigital, Inc.
> # Last Edit:	29 March 2011
> #
> # Synopsis:
> #	This script uses inotifywait to watch for newly uploaded files
> #	in the /opt/uploads directory.  When something is uploaded, it
> #	runs rsync to copy the file to another machine.
> #		
> # NOTES:
> #	It's probably best to run this script in a screen(1) session or
> #	via "nohup /usr/local/bin/watchuploads.sh >/dev/null 2>&1 &".
> #
>
> # Set up some variables to make life easier...
> WATCHPT="/opt/uploads"			# Directory to watch for uploads
>
> # And away we go...
> while /bin/true; do			# Start infinite loop
>     FNAME=`inotifywait -e close_write --format "%f" $WATCHPT
> 2>/dev/null`					# Watch for changes and grab
> 					# filename
>     nohup rsync $WATCHPT/$FNAME remotemachine:$WATCHPT/ \
> 	 >>/dev/null 2>&1 &		# Launch rsync
> done
> ------------------------------- CUT HERE -----------------------------
>
> This is FAR more efficient than doing a sleep(1) and won't put as much
> of a load on the system. Look at the man pages for inotifywait(1),
> inotifywatch(1) and inotify(7).
> ----------------------------------------------------------------------
> - Rick Stevens, Systems Engineer, C2 Hosting          ricks at nerd.com -
> - AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
> -                                                                    -
> -       Charter Member of the International Sarcasm Society          -
> -                "Yeah, like we need YOUR support!"                  -
> ----------------------------------------------------------------------
>
>   


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/redhat-install-list/attachments/20110701/660f411a/attachment.htm>