is there some sort of catchable trigger when one writes/deletes a new file in linux?

Question

I would like a simple tool for syncing two folders on remote servers...

Utopically, I only need an OS catchable trigger (or something like that) that could be used to fire rsync automatically ?

Is there anything of the sort, or a simple tool capable of doing this ?

rsync each minute is not at all an elegant solution to the problem ... i would like to call rsync each time a file is written/deleted in any one of the servers, in a specific folder...

the goal is to easily maintain to remote folders in sync

update: maybe something like gamin... ?

thanks !

arod

score 3 · Answer 1 · edited Apr 13 '17 at 12:14

3

In my answer to this question, I suggested incron. It's easy to set up system-wide and user-specific config files in a manner similar to cron. You can specify scripts that will be run when filesystem events are triggered. It uses the Linux kernel inotify API. You might take a look at it and see if it works for you.

edited Apr 13 '17 at 12:14

Community

1

answered Jun 28 '10 at 02:36

Dennis Williamson

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Ooh, that's cool. I'll need to add that to my toolbox for future usage. – EEAA Jun 28 '10 at 02:39
Ooh +1, I feel smarter just for now knowing that exists. – Jun 28 '10 at 05:52
i notify is very cool ! it does not, however, monitor sub directory's... : ( – arod Jun 28 '10 at 12:32
@arod: That's true, `inotify` doesn't do recursive monitoring. You would need to add an `incron` rule for each specific directory. – Dennis Williamson Jun 28 '10 at 12:58
yep, and thats a bit cumbersome... directories pop in and out of existence erraticaly ; ) – arod Jun 28 '10 at 13:22

score 2 · Answer 2 · answered Jun 28 '10 at 14:26

Try inotify. For your relative simple requirements this should be best suited.

An example script:

while { inotifywait -e create -e delete /directory2watch; }; do
  echo rsync -avz /directory2watch
done

Or something like that.

With inotify you have access to those events:

access – file was accessed
modify – file was modified
attrib – file attributes changed
close_write – file closed, after being opened in writeable mode
close_nowrite – file closed, after being opened in read-only mode
close – file closed, regardless of read/write mode
open – file was opened
move – a file within watched directory was moved
create – a file was created within watched directory
delete – a file was deleted within watched directory
delete_self – the watched file was deleted
unmount – file system on which watched file exists was unmounted

inotify is excellen, but it get cumbersome when tracking directories and subdirectories... — arod, Jun 29 '10 at 10:52
At least inotifywait knows the `-r` option for recursive monitoring. I don't know how good it works though. — weeheavy, Jun 29 '10 at 11:22

score 1 · Answer 3 · answered Jun 28 '10 at 02:28

1

It seems like DRBD will do just what you need. It works at the block device level, so if you don't want to maintain a separate partition for this synchronized data, you can just create a disk image and mount it loopback, using DRBD to keep things in sync with the remote server.

answered Jun 28 '10 at 02:28

EEAA

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it's right that using DRBD sound like the right solution, things like "you can just create a disk image and mount it loopback" are not so clear. i didnt like drbd because i needed to store my files in a different partition, seems like to big a solution for syncing a couple of folders... if you could explain how to "create a disk image and mount it loopback", can this be used to sync a couple of folders ? thanks !! – arod Jun 28 '10 at 12:35

score 0 · Answer 4 · answered Jun 28 '10 at 14:10

0

The obvious solution here is afs

There all sorts of complications using DRBD on anything but a small LAN with high levels of connectivity between nodes.

But you could roll your own solution using inotify

answered Jun 28 '10 at 14:10

symcbean

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afs seems very cool, and very suited to my needs, i'll take a look ! thank you very much ! : ) – arod Jun 29 '10 at 10:52

is there some sort of catchable trigger when one writes/deletes a new file in linux?

4 Answers4