On Thu, 8 Oct 1998, Martin Schulze wrote: > This might be an faq. > > But occasionally I notices that dpkg first unpacks and installs > the files in a particular package and checks dependencies afterwards. > > This means that wrong dependencies are discovered when it is > too late since the old version of the package is already > overwritten. > > I'm sure there is a rationale for this, but what is it?
The rationale is that this would make package installing too much troublesome, if not impossible in some cases. In particular, if A depends on B and B depends on A, you would be unable to install A and B at all. With the current design, you can. > At least I would have expected that dpkg tests the dependency > of new packages and refuses to unpack them - unless one told > it to ignore dependencies. This is exactly the case for Pre-Dependencies, and that's the reason why essential packages need Pre-Dependencies as a general rule (we can not afford to have them broken at *any* time). For non-essential packages, the user is supposed to be able to use the packaging system (dselect, dpkg, etc.), which is supposed not to be broken thanks to the Pre-dependencies, to satisfy any remaining broken (not Pre-)dependencies. -- "f1d425529e79e6faba09bd7e97315457" (a truly random sig)
