make duplicate copies of files

Paul Griesbaum · 06-08-2009, 10:01 AM

I'm using Mandriva 2009 and was wondering if I could somehow save a document or other file in multiple locations? Here's what I'd like to do:
I've created a backup folder. Is there someway to save files to that backup folder at the same time the file is being saved to another location?

jamescondron · 06-08-2009, 10:04 AM

There are a few ways you could script this, though I'm not sure of a native way.

i92guboj · 06-08-2009, 10:12 AM

I know of no native way (well, what I understand by "native" anyway). In first place, there's no way that Linux can now which files need to be backed, and which of them do not.

So you have to resort to a more defined criteria. For example, files that are saved on a given directory but only when they have a given extension, or something similar. If you can concrete the conditions under which a file is a candidate for backup, then we might come with a solution based on inotify, which would be the cleanest thing I can think of.

Paul Griesbaum · 06-08-2009, 10:19 AM

Well, like say something like an abiword file with the abw extension. How could I save a file like this to two different folders? Is there some type of syncing app in the repositories that could do this?

jamescondron · 06-08-2009, 10:22 AM

Why not a little script that checks every n seconds for changes in filesize to .abw files in a specific directory. If true, copy

schneidz · 06-08-2009, 10:30 AM

maybe you can cron something like this once a day:

Code:

for file in `find ~/stuff`
do
 cp $file ~/bak/$file.`date +%j`
done

by and by, i havent tested this yet; season to taste...

mcolangelo · 06-08-2009, 10:34 AM

a script with inotifywait seem like the easiest solution. Something like

Code:

while inotifywait -m -e modify /path/to/primary-save-location/
do
   if [ -f %f ]; then
	cp %f /to/other/save/location
   fi
done

That will watch for changes in "/path/to/primary-save-location/". Then when a change occurs it will verify that the file that triggered the change exists and then copy it to /to/other/save/location

I didn't have a chance to test it, but it looks about right

i92guboj · 06-08-2009, 10:39 AM

Many approaches could work. If you don't care about it being instantaneous, you can do a cron job to sync it. With this approach you could use rsync, which would take care of the syncing and would only copy the files that are new or need to be updated.

If you need instant sync in the same moment that you save the file, then inotify is the way to go, if you have the inotify tools installed you could do something like this:

Code:

inotifywait tmp/1 --event create --event modify --format=%f --monitor \
  | while read filename
    do
      cp --force "$filename" /some/other/directory/
    done

Untested, so make your checks and make sure you understand the snippet before you use it. Another matter would be how to launch this, if your distro has some kind of file to launch custom scripts at init, you could run this from there (i.e. /etc/rc.d/rc.local or something like that, in Gentoo we have /etc/conf.d/local.start). Wrapped into a

Code:

su your_user_name -c '<insert the above snippet here>'