How can we automaitcally sync/copy files from one directoy to another ?

Shell Programming and Scripting
1

Hi,

I would like to achieve below requirement,

I have a directory "/mydir" and I want to automatically sync/copy all the content of /mydir directory to "/yourdir" directory all the time.
meaning, if some application creates a file in /mydir, it supposed to be copied/available in "/yourdir" directory

I need to have two copies.

Can we do this using rsync ? or hard link ? (*both /mydir and /yourdir available in same server)

please explain. Thanks.

2

the link will not result in "two copies" as you say. The rsync is ideal tool for this task IMO.

the simplest form would be

rsync -a source target

If you delete a file from your source and want it to be deleted from your target rsync does that as well.

3

As migurus said, a hard link doesn't create a copy of a file; it creates another name for a single file.

And, even if /mydir and /yourdir are on the same server, you can't create a hard link between files in those directories unless both of those directories are in the same filesystem (i.e. under the same mount point) on that server.

4

And to constantly check if the content of a directory has changed, you would need to write either:

  • Your own service, which then invokes rsync
  • A script that checks your path every single second, and if there was a change, start rsync - if it is not alredy running...

Which both is about the same in the effect, obviously...

You do NOT want start a new instance to rsync syncinc a multi GB large folder to another ever second.

hth

5

Hi.

Linux has a feature called intotify:

DESCRIPTION
       The  inotify API provides a mechanism for monitoring filesystem events.
       Inotify can be used to monitor individual files, or to monitor directo
       ries.   When  a  directory is monitored, inotify will return events for
       the directory itself, and for files inside the directory.

which is accessible from the shell with:

 inotify-tools is a set of command-line programs for Linux providing a
 simple interface to inotify. These programs can be used to monitor and
 act upon filesystem events. inotify-tools consists of two utilities:
 .
 inotifywait simply blocks for inotify events, making it appropriate
 for use in shell scripts.
 .
 inotifywatch collects filesystem usage statistics and outputs counts
 of each inotify event.

So one could run inotifywait which would block execution of a script until there was a change, then the script could call rsync , then start all over again.

Best wishes ... cheers, drl