replace file with hardlink to another file atomically
- by Ben Clifford
I have two directory entries, a and b.
Before, a and b point to different inodes.
Afterwards, I want b to point to the same inode as a does.
I want this to be safe - by which I mean if I fail somewhere, b either points to its original inode or the a inode. most especially I don't want to end up with b disappearing.
mv is atomic when overwriting.
ln appears to not work when the destination already exists.
so it looks like i can say:
ln a tmp
mv tmp b
which in case of failure will leave a 'tmp' file around, which is undesirable but not a disaster.
Is there a better way to do this?
(what I'm actually trying to do is replace files that have identical content with a single inode containing that content, shared between all directory entries)
