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Leveraging --force-* to Repair Broken Dependencies
If you are not careful, the use of a --force-* option or some other malfunction can lead to a system where the APT family of commands will refuse to function. In effect, some of these options allow
installation of a package when a dependency is not met, or when there is a conflict. The result is an inconsistent system from the point of view of dependencies, and the APT commands will refuse to execute any action except those that will bring the system back to a consistent state (this often consists of installing the missing dependency or removing a problematic package). This usually results in a message like this one, obtained after installing a new version of rdesktop while ignoring its dependency on a newer version of libc6:
# apt full-upgrade
[...]
You might want to run ’apt-get -f install’ to correct these. The following packages have unmet dependencies:
rdesktop: Depends: libc6 (>= 2.5) but 2.3.6.ds1-13etch7 is installed E: Unmet dependencies. Try using -f.
# apt full-upgrade
[...]
You might want to run ’apt-get -f install’ to correct these. The following packages have unmet dependencies:
rdesktop: Depends: libc6 (>= 2.5) but 2.3.6.ds1-13etch7 is installed E: Unmet dependencies. Try using -f.
If you are a courageous administrator who is certain of the correctness of your analysis, you may choose to ignore a dependency or conflict and use the corresponding --force-* option. In this case, if you want to be able to continue to use apt or aptitude, you must edit /var/lib/dpkg/status to delete or modify the dependency, or conflict, that you have chosen to override.
This manipulation is an ugly hack and should never be used, except in the most extreme case of necessity. Quite frequently, a more fitting solution is to recompile the package that is causing the problem or use a new version (potentially corrected) from a repository providing backports (backports are newer versions especially recompiled to work in an older environment).