Comment 6 for bug 262811

Ah, you talk about symlinks, while the referenced mail talks about hardlinks. That's where my initial confusion came from.

I confirm that mv is not atomic in dapper, hardy and intrepid when using hardlinks:

$ echo foo >foo; echo bar > bar; ln foo foo.backup
$ strace mv bar foo
[...]
access("foo", W_OK) = 0
unlink("foo") = 0
rename("bar", "foo") = 0
[...]

As for symlinks, I used this test case:

$ rm -f *; ln -s file1 link; ln -s file2 link.new; strace -e access,rename,unlink mv link.new link

In Hardy and Intrepid I get the correct behaviour:

rename("link.new", "link") = 0

while in Dapper I get:

unlink("link") = 0
rename("link.new", "link") = 0

I checked the intrepid sources, and this is covered by tests/mv/atomic (with pretty much the same approach).