Tar and hard links.

[Ben Stringer]

On Sun, 2004-05-02 at 03:56, WipeOut wrote:
> How does tar handle hard links?? Is there a switch to use or does it 
> handle them automatically??
> 
> I looked through the man page and only saw a reference to symlinks but 
> not hard links..

I was surprised by the answers saying tar would "efficiently" handle
hard links, so thought I would try it out. It was easy to confirm - I
used a copy of the "ls" as the contents of my first tarfile, then the
same executable and a hardlink to it in the second tar file. The 2
tarfiles are the same size, and a verbose table of contents on the
second tarfile shows tar is aware of the link.

Hope this is helpful to those interested.

Cheers, Ben

[ben at hillary hardlinktest]$ cp /bin/ls .
[ben at hillary hardlinktest]$ ls -l
total 80
-rwxr-xr-x  1 ben ben 76188 May  4 23:58 ls
[ben at hillary hardlinktest]$ tar cf t1.tar ls
[ben at hillary hardlinktest]$ ls -l
total 164
-rwxr-xr-x  1 ben ben 76188 May  4 23:58 ls
-rw-rw-r--  1 ben ben 81920 May  4 23:58 t1.tar
[ben at hillary hardlinktest]$ ln ls ls2
[ben at hillary hardlinktest]$ tar cf t2.tar ls ls2
[ben at hillary hardlinktest]$ ls -l
total 328
-rwxr-xr-x  2 ben ben 76188 May  4 23:58 ls
-rwxr-xr-x  2 ben ben 76188 May  4 23:58 ls2
-rw-rw-r--  1 ben ben 81920 May  4 23:58 t1.tar
-rw-rw-r--  1 ben ben 81920 May  4 23:58 t2.tar
[ben at hillary hardlinktest]$ tar tvf t2.tar 
-rwxr-xr-x ben/ben       76188 2004-05-04 23:58:23 ls
-rwxr-xr-x ben/ben           0 2004-05-04 23:58:23 ls2 link to ls