[augeas-devel] Re: [Puppet Users] Testing help for new Augeas Puppet provider which only executes if required

[David Lutterkort]

On Fri, 2009-02-20 at 07:53 -0500, Bryan Kearney wrote:
> One question.... If I have a file with 10 nodes, does augeas re-write 
> the whole file, or just scan for the nodes which changed?

It will write a new file (into a tmp location) and then replace the old
file with the new one. Since rename(2) is the only way to modify files
atomically, it's generally a bad idea to modify files that could be in
the process of being read/written by others in place[1].

David

[1] Augeas will fall back to modifying in place under certain
circumstances, most importantly when the file is bindmounted, since you
can't use rename in that case.