Weblog entry #22 for fsateler
aptitude search '?for x:
Now, lets go over the query. The first part ?for x: allows us to refer to the package currently being matched. See the documentation for details. We'll see later why we need this. Basically we are saying: give me all packages x that match the following pattern. The second and third parts are trivial: we only want automatically installed packages.
The fourth part, ?x:provides(?virtual ?reverse-depends(?installed)) was easy: find all packages that provide a virtual package that is depended upon by some other installed package.
The fifth and final part, ?not(?x:reverse-depends(?installed(?depends(?=x)))) is why we needed the bound variable x. We want to filter out (hence the ?not) the packages that have some reverse dependency that depends directly on the package x. That way, in my case, metacity won't show up since gnome-core directly depends on it and is installed.
Unfortunately, this query doesn't grok alternative dependencies. For example, if gnome-core depended on metacity | x-window-manager then this query wouldn't show metacity, since it is depended upon by a package. If someone can make this query understand that so that it only eliminates packages directly depended upon with no alternatives dependencies, please let me know!
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