[K12OSN] Not recreating the wheel

Jim Wildman jim at rossberry.com
Fri May 14 13:56:52 UTC 2004

On Fri, 14 May 2004, Christopher K. Johnson wrote:

> >
> The tricky thing about using rsync, is that you need to make it work in 
> the correct direction.  When not logged in at an alternate location it 
> needs to sync all other sites to the person's primary site.  When logged 
> in at an alternate location it needs to sync all other sites to that 
> alternate copy of their home directory.  And if you do it with cron jobs 
> there is a problem with changes after logging off at an alternate site 
> being sync'd the wrong way.  So you need to  manage some state 
> indicator  (a file touched at logon and cleared by cron job only if the 
> person is no longer logged on) that will enable the cron job to do the 
> right thing that one last time after logoff.
> By the way, what will remain problematic in the rsync scenario is if 
> someone actually does log on remotely to a system.  The worst case is 
> when they simultaneously log on to more than one system.  What should 
> the rsync cron jobs do then and how will they detect that condition to 
> accomodate it?  Perhaps you need to tell people "don't log on to more 
> than one server at a time".

Good points.  Login and logout scripts can be useful too.

Might check out Unison as well.

Jim Wildman, CISSP, RHCE                                jim at rossberry.com

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