On 16/01/2008, William Case <billlinux@xxxxxxxxxx> wrote: > > In this case, what is metadata? A high-level file format created to be used by various package resolver tools: http://linux.duke.edu/projects/metadata/ > Where is it on a file (package) It is stored in multiple files in a directory with the name "repodata" in the same place where the RPM packages are stored. To create it you would run createrepo in the top-level package directory to make it fill the repodata directory with metadata for all found packages. createrepo traverses the given directory and its sub-directories recursively. > and how does Yum read it? Yum is pointed to repositories via config files in /etc/yum.repos.d/ and uses URLs to access the "repodata" directories and the files within. Nowadays there's a metadata parser for these files: http://linux.duke.edu/projects/yum/download/yum-metadata-parser/ > Does it use its own specialized instructions to access data or does it > use some version of 'wget'? From the top of my head, it uses networking methods from Python Standard Library, e.g. urllib, instead of an external tool. > > that contain RPM packages plus the > > corresponding metadata archives generated by the createrepo tool. > > How does the creatrepotool create an archive? What is needed etc? Put some RPM packages into a directory, run "createrepo" in or above that directory. See "man createrepo". Notice the "repodata" directory and the files within it which are created. $ rpm -qf $(which createrepo) createrepo-0.4.11-1.fc8 > I suppose analyzing how createreptool creates an archive answers most of > the metadata questions? Where would I find an *explanation* of how to > go about creating a repo or a package for a repo? You can put any RPM package into such a repository. And yes, reading the source would help here. $ rpm -ql createrepo | grep .py$ /usr/share/createrepo/dumpMetadata.py /usr/share/createrepo/genpkgmetadata.py /usr/share/createrepo/modifyrepo.py /usr/share/createrepo/readMetadata.py > Where, and more importantly what is the info regarding each package > stored in the local RPM database? It's similar to all the package details you can query with rpm, e.g. $ rpm --query --requires glibc glibc-common = 2.7-2 basesystem libgcc /usr/sbin/glibc_post_upgrade.i686 /sbin/ldconfig rpmlib(PartialHardlinkSets) <= 4.0.4-1 rpmlib(PayloadFilesHavePrefix) <= 4.0-1 rpmlib(CompressedFileNames) <= 3.0.4-1 and the many other queries that are covered by "man rpm". Yum/createrepo do it via the RPM Python API, however, instead of low-level C/C++. > How does yum find it and read it? I've answered that in the previous reply. Yum parses repository metadata files and also queries the local RPM database via RPM's API. > * What precisely is a package? http://rpm.org/ answers that one the first page. > * What and Where is this temp directory? That's implementation-dependent and a low-level question. > * What checks are it running (you have alluded to them above)? > * What exactly is a *transaction*? Transaction is a database related term here and covers the full set of changes to be applied to the local installation *and* in the RPM database: http://en.wikipedia.org/wiki/Database_transaction > * What does cleaning up (cleanall etc.) mean? Is something being > removed or just changed? Roughly, there's stuff to do *after* replacing an old version of a package installed on your system with a newer version.
