--link-dest on a local filesystem

[Jaco Kroon]

Hi guys,

I've been struggling with getting --link-dest working for a couple of
hours now.  I'm using rsync 2.6.9 (protocol 29), on Gentoo Linux.

For some strange reason, whenever I recreate the source file, even
though it's identical to the old source file --link-dest simply does not
create the link.  Point in case (starting from a blank directory tmp in
my home directory):

jkroon at pug ~/tmp $ mkdir a
jkroon at pug ~/tmp $ echo foo > a/tmp
jkroon at pug ~/tmp $ rsync -va --link-dest=../b.1 a/ b.0/
building file list ... done
created directory b.0
./
tmp

sent 142 bytes  received 48 bytes  380.00 bytes/sec
total size is 4  speedup is 0.02
jkroon at pug ~/tmp $ rm a/tmp
jkroon at pug ~/tmp $ echo foo > a/tmp
jkroon at pug ~/tmp $ mv b.0 b.1
jkroon at pug ~/tmp $ rsync -va --link-dest=../b.1 a/ b.0/
building file list ... done
created directory b.0
./
tmp

sent 143 bytes  received 49 bytes  384.00 bytes/sec
total size is 4  speedup is 0.02
jkroon at pug ~/tmp $ md5sum b.*/tmp
d3b07384d113edec49eaa6238ad5ff00  b.0/tmp
d3b07384d113edec49eaa6238ad5ff00  b.1/tmp
jkroon at pug ~/tmp $ stat b.*/tmp
  File: `b.0/tmp'
  Size: 4               Blocks: 8          IO Block: 4096   regular file
Device: 306h/774d       Inode: 183267      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1001/  jkroon)   Gid: (  100/   users)
Access: 2007-03-08 20:50:31.000000000 +0200
Modify: 2007-03-08 20:50:24.000000000 +0200
Change: 2007-03-08 20:50:31.000000000 +0200
  File: `b.1/tmp'
  Size: 4               Blocks: 8          IO Block: 4096   regular file
Device: 306h/774d       Inode: 183111      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1001/  jkroon)   Gid: (  100/   users)
Access: 2007-03-08 20:50:12.000000000 +0200
Modify: 2007-03-08 20:49:51.000000000 +0200
Change: 2007-03-08 20:50:12.000000000 +0200

Ok, so perhaps the -a which includes --times mucks things up, so add
--no-times:

jkroon at pug ~/tmp $ rm -rf *
jkroon at pug ~/tmp $ mkdir a
jkroon at pug ~/tmp $ echo foo > a/tmp
jkroon at pug ~/tmp $ rsync -va --no-times --link-dest=../b.1 a/ b.0/
building file list ... done
created directory b.0
./
tmp

sent 142 bytes  received 48 bytes  380.00 bytes/sec
total size is 4  speedup is 0.02
jkroon at pug ~/tmp $ rm a/tmp
jkroon at pug ~/tmp $ echo foo > a/tmp
jkroon at pug ~/tmp $ mv b.0 b.1
jkroon at pug ~/tmp $ rsync -va --no-times --link-dest=../b.1 a/ b.0/
building file list ... done
created directory b.0
./
tmp

sent 143 bytes  received 49 bytes  384.00 bytes/sec
total size is 4  speedup is 0.02
jkroon at pug ~/tmp $ md5sum b.*/tmp
d3b07384d113edec49eaa6238ad5ff00  b.0/tmp
d3b07384d113edec49eaa6238ad5ff00  b.1/tmp
jkroon at pug ~/tmp $ stat b.*/tmp
  File: `b.0/tmp'
  Size: 4               Blocks: 8          IO Block: 4096   regular file
Device: 306h/774d       Inode: 183267      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1001/  jkroon)   Gid: (  100/   users)
Access: 2007-03-08 20:53:03.000000000 +0200
Modify: 2007-03-08 20:53:03.000000000 +0200
Change: 2007-03-08 20:53:03.000000000 +0200
  File: `b.1/tmp'
  Size: 4               Blocks: 8          IO Block: 4096   regular file
Device: 306h/774d       Inode: 183111      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1001/  jkroon)   Gid: (  100/   users)
Access: 2007-03-08 20:52:51.000000000 +0200
Modify: 2007-03-08 20:52:51.000000000 +0200
Change: 2007-03-08 20:52:51.000000000 +0200
jkroon at pug ~/tmp $

Still no hard link ... If someone could just explain to me why this
behaviour happens, and if it can be avoided, it would be much appreciated.

Jaco