424 CHAPTER 29 INSTALLING SOFTWARE Removing Software (Free web servers)
424 CHAPTER 29 INSTALLING SOFTWARE Removing Software To remove a piece of software, search for it by name, then click the check box alongside it, and then select Mark for Removal. This will remove the software but leave behind any configuration files it created. This means you can install it again in the future, and it will function as it did before removal. However, you can also select Mark for Complete Removal, which will remove the configuration files. As with installing software, the Synaptic Package Manager will attempt to manage depen dencies when you remove software, but in this case, it will enforce the removal of any software that explicitly relies on that software. This isn t an issue most of the time, but unfortunately, some packages have major reverse dependencies. For example, if you decide that you ve had enough of the Base database program and want to remove it, you ll find that you ll also need to remove the entire OpenOffice.org suite, as well as the ubuntu-desktop metapackage. Sometimes, packages have what seem like weird dependencies. For example, if you try to remove the Firefox web browser, you ll see that you need to remove the seemingly unrelated gnome-app-install package, as well as yelp, the GNOME online help system. The reason for this is that both these packages use a component of Firefox in some way and simply can t func tion without it. There isn t a hard-and-fast solution for situations like this. However, in many cases, you might simply choose to not remove the software and leave it on your system. Package Management from the Command Prompt Synaptic is one of the best examples of package-management programs around, and there s little reason to shun it and choose to install packages from the command line. However, you may find occasions to use dpkg or the APT tools. For example, if you re already working at the command line, then this method is quicker than starting up the Synaptic Package Manager. Using dpkg The most basic package-manipulation command is dpkg. dpkg allows you to perform a lot of package-related tasks, such as build packages from scratch. Here, we ll look at just simple package installation, removal, and query functions. Note dpkg requires superuser powers to install or remove software, so must be preceded with sudo. But it can be run without superuser powers if you simply wish to query the package database. The same is true of the APT tools discussed later. Installing Packages dpkgis useful when you ve already downloaded a specific .deb package and would like to install it. Here is the command: sudo dpkg -i packagename.i386.deb