rsync behavior with symlinks

keviny22 · 02-24-2011, 04:57 PM

I am having issues with getting rsync to operate the way i am expecting it to with symlinks, any advice would be greatly appreciated.

I am trying to do an rsync that includes a symlink in a folder. I only want the symlink to change on the destination if the mod time of the symlink on the source is newer. The behavior i am seeing is that the symlink on the destination is always updated to match the source regardless of the mod time.

Here is the command I am passing:

Code:

rsync --links --update --archive --exclude "*/" /var/tmp/links/* -e ssh user@dest.example.com:/var/tmp/links/

lrtward · 02-25-2011, 02:26 PM

Are you 100% certain that's what's happening?

I did some testing here and what I see is that the original file and the rsync'd file have the same timestamps; that is, changes to the original file cause the timestamp to be updated and the updated time is carried over to the rsync destination. The symlink has the same timestamp as the original file.

I think an example will show it more clearly:

Code:

$ ls -l
-rw-rw-r-- 1 ltward ltward   16 Feb 25 15:13 thefile

$ date
Fri Feb 25 15:15:30 EST 2011

$ ln thefile linkfile
$ ls -l
-rw-rw-r-- 2 ltward ltward   16 Feb 25 15:13 linkfile
-rw-rw-r-- 2 ltward ltward   16 Feb 25 15:13 thefile

So here the symlink has the same timestamp as the "real" file.
Now I make a directory and rsync to it.

Code:

$ mkdir syncdir
$ date
Fri Feb 25 15:17:01 EST 2011

$ rsync * --links --update --archive --exclude 'syncdir' syncdir
$ ls -l syncdir
-rw-rw-r-- 1 ltward ltward   16 Feb 25 15:13 linkfile
-rw-rw-r-- 1 ltward ltward   16 Feb 25 15:13 thefile

Now my symlink and real file at the rsync destination have the same timestamp as the "real" file.
I'll edit the original file and see if that affects the symlink or the rsync'd symlink.

Code:

$ date
Fri Feb 25 15:19:00 EST 2011
$ vi thefile
$ ls -l
-rw-rw-r-- 2 ltward ltward   21 Feb 25 15:19 linkfile
drwxrwxr-x 3 ltward ltward 4096 Feb 25 15:17 syncdir
-rw-rw-r-- 2 ltward ltward   21 Feb 25 15:19 thefile

$ date
Fri Feb 25 15:20:07 EST 2011
$ rsync * --links --update --archive --exclude 'syncdir' syncdir
$ ls -l syncdir
-rw-rw-r-- 1 ltward ltward   21 Feb 25 15:19 linkfile
-rw-rw-r-- 1 ltward ltward   21 Feb 25 15:19 thefile

So my rsync'd symlink file is keeping the timestamp of the "real" file.
I'm on CentOS 5.5

As long as your symlink points to the correct file, does it matter what the timestamp is?

keviny22 · 02-28-2011, 12:59 PM

Thanks for the response, here is a bit more detail and the specific example.
Here you see that on two servers, we have the same link called honda.link pointing to two different files.
The date of the link on dest.example.com is newer

Code:

[root@source.example.com links]# ls -l
-rw------- 1 root root    0 Feb 28 10:45 accord.file
-rw------- 1 root root    0 Feb 28 10:45 civic.file
lrwxrwxrwx 1 root root   10 Feb 28 10:46 honda.link -> civic.file

[root@dest.example.com links]# ls -l
-rw------- 1 root root    0 Feb 28 10:46 accord.file
-rw------- 1 root root    0 Feb 28 10:46 civic.file
lrwxrwxrwx 1 root root   11 Feb 28 10:47 honda.link -> accord.file

Now I rsync

Code:

[root@source.example.com links]# rsync --links --update --archive --exclude "*/" /var/tmp/links/* -e ssh root@dest.example.com:/var/tmp/links/

Looking at dest.example.com the link changed to match source.example.com even though the link on dest.example.com had a newer timestamp.

Code:

[root@source.example.com links]# ls -l
-rw------- 1 root root  0 Feb 28 10:45 accord.file
-rw------- 1 root root  0 Feb 28 10:45 civic.file
lrwxrwxrwx 1 root root 10 Feb 28 10:46 honda.link -> civic.file

[root@dest.example.com links]# ls -l
-rw------- 1 root root  0 Feb 28 10:46 accord.file
-rw------- 1 root root  0 Feb 28 10:46 civic.file
lrwxrwxrwx 1 root root 10 Feb 28 10:48 honda.link -> civic.file

I would expect that the link on the dest.example.com would be skipped because it is newer