Software Package Problems

6.10 Recognize common errors (e.g., package dependencies, library errors, version conflicts)

Sometimes, when trying to install a software package, you will find that the package requires extra programs to run properly, or that the package conflicts with a version of another application that you are running.

Software package problems are very common, but fairly easy to solve after you know what you’re looking for.

Some advanced package managers will install dependent programs for you. Sometimes, this can cause more problems than it solves because the dependent program may conflict with another existing application.

Package dependencies

Software package managers, such as RPM (Redhat Package Manager) and DPKG (the Debian package manager), will tell you immediately if you are lacking any dependencies that the current package requires. Applications can have all types of dependent programs, such as programming run-time libraries or modules. Package managers contain special control files, which keep track of the dependencies for the package. If you don’t have the required dependent software, the new package won’t install and you will receive an error message telling you what you’re missing.

Using this information from the error message, you can obtain the correct dependent software, install it, and then try to install your original package again.

Package managers also keep track of dependencies when you are removing a package, so you won’t accidentally delete a file or library that another program depends on.

Software and version conflicts

When a new software program is installed, it may have components that conflict with other programs already installed. For example, if you installed a new package that contains newer versions of run-time libraries that another program requires, you may cause the already existing program to stop working. This happens because the existing program was dependent on the older version of the run-time library that you replaced. If you need both programs, you may have to track down a library that is compatible with both programs.

When installing a new package, read over the installation README file to ensure that what you are installing won’t conflict with existing software.

Be able to recognize the symptoms of a software dependency or conflict.