Synaptic is a friendly, easy-to-use frontend (GUI) to the APT packaging system. It is a graphical tool that allows you to install, remove, upgrade, downgrade, or get information on all the software packages available in the online repositories on your repository list. Note that your root password is required and, naturally, you will need to be connected to the Internet.
Here are the basic steps for installing software in Synaptic:
- Click Start menu > System > Synaptic Package Manager, supplying the root password if asked.
- Hit the Reload button. This button causes Synaptic to contact the online repository servers and download a new index file with information on what packages are available, what versions they are, and what other packages are required for them to be installed. If you get a message that some of the repositories failed to be contacted, wait a minute and then try again.
- If you already know the name of the package you are looking for, just click in the pane on the right and start typing, and Synaptic will incrementally search for what you type.
- If you don’t know the package’s name, use the Search box in the upper right corner to locate software based on name or keywords. This is one of Synaptic’s greatest advantages over other methods.
Alternatively, use one of the filter buttons in the bottom left corner:
- Sections provides subareas such as Editors, Games and Amusement, Utilities, etc. You will see a description of each package in the bottom pane, and can use the tabs to discover more information about it.
- Status groups packages by their installation situation.
- Origin will show packages from a specific repository.
- Custom Filters provides various filter options
- Search Results will show a list of previous searches for the Synaptic session you are in.
- Click the empty box next to the package you want and select Mark for Installation. If the package has dependencies, you will be notified and they will automatically be marked for installation as well. You can also just double-click the package if it is the only one you are installing.
- Some packages also have “Recommended” and “Suggested” packages that can be viewed via right-clicking the package name. These are additional packages that add functionality to the selected package, and it is a good idea to look them over.
- Click Apply to begin the installation. You can safely ignore any warning message: “You are about to install software that can’t be authenticated!”
- There may be additional steps: just follow the prompts as you receive them until the installation completes.
Figure 5-2: Checking recommended packages during package installation.
Removing software from your system with Synaptic seems as straightforward as installing, but there is more to it than meets the eye:
To remove a package, simply right-click it and select Mark for Removal or Mark for Complete Removal.
- Removal uninstalls the software, but leaves system configuration files in case you want to keep your settings.
- Complete Removal removes the software and the system configuration files as well (purging). Your personal configuration files related to the package will not be removed. Check also for other configuration file remnants in Synaptic’s category Not installed (residual config).
- When you have other programs that depend on the package being removed, those packages will have to be removed as well. This usually happens when you remove software libraries, services, or command-line applications that serve as back-ends to other applications. Make sure you read carefully the summary Synaptic gives you before clicking OK.
- Removing large applications that are composed of many packages can bring complications. Many times these packages are installed using a meta-package, which is an empty package that simply depends on all the packages you need for the application. The best way to remove a complicated package like this is to inspect the dependency list for the meta-package, and remove the packages listed there. Take care, however, that you don’t uninstall a dependency of another application you want to keep!
- You may find that the status category Autoremoveable begins to accumulate packages. These were installed by other packages and are no longer needed, so you can click on that status category, highlight all the packages in the right pane, and then right-click them to remove. Be sure to examine the list carefully when the verification box appears, because sometimes you may find that the dependencies listed for removal include packages you actually want to keep. Use apt -s autoremove to do a simulated (= the -s switch) dry run if you’re unsure.
Figure 5-3: Getting ready to clear out the autoremovable packages.
Synaptic enables you to quickly and conveniently keep your system up-to-date.
Unless you are using a manual method in Synaptic or a terminal, upgrading is typically triggered by the a ahcnge in the MX Updater icon in the Notification Area (default: empty box turns green). There are two ways to proceed when this arrow appears.
- Left-click the icon. This is the faster method because there is no wait for software to load, run, etc. A terminal window appears with the packages to upgrade; examine them carefully, then click OK to complete the process.
Right-click the icon to use Synaptic instead.
- Click the Mark All Upgrades icon below the menu bar to select all available packages for upgrade, or click on the Installed (upgradable) link in the left panel to review the packages or to select upgrades individually.
- Click Apply to begin the upgrade, ignoring the warning message. As the installation process begins, you have the option of watching the details in a terminal within Synaptic.
- With some package upgrades, you may be asked to confirm a dialog, enter configuration information, or decide whether or not to overwrite a configuration file you have altered. Pay attention here, and follow the prompts until the upgrade completes.
Sometimes you may want to downgrade an application to an older version, for instance because of problems that arose with the new one. This is easy to do in Synaptic:
- Open Synaptic, supply the root password, and click Reload.
- Click on Installed in the panel on the left, then find and highlight the package you want to downgrade in the panel on the right
- On the menu bar, click Package > Force version...
- Select from the available versions on the pull-down list
- Click Force Version, then install in the usual manner.
- To keep that lower version from immediately being upgraded again, you need to pin it.
Figure 5-4: Using Force version to downgrade a package
Sometimes you may want to pin an application to a specific version to keep it from being upgraded in order to avoid problems with more recent ones. This is easy to do:
- Open Synaptic, supply the root password, and click Reload.
- Click on Installed in the panel on the left, then find and highlight the package you want to pin in the panel on the right.
- On the menu bar, click Package > Lock version...
- Synaptic will highlight the package in red and add a lock icon to the first column.
- To unlock, highlight the package again and click Package > Lock version (which will have a check mark).
- Note that pinning via Synaptic does not prevent the package from being upgraded when using the command line.
Synaptic is very reliable, but sometimes you may get an error message. A full discussion of such messages may be found in the MX/antiX Wiki, so here we will only mention a couple of the most common.
- You get a message that some repos failed to download repository information: this is usually a transient event, and you simply need to wait and reload.
- If the installation of a package shows that software you want to keep will be removed, click Cancel to back out of the operation.
- It may happen with a new repository that you see an error message after reloading that says something like: W: GPG error: [some repository URL] Release: The following signatures couldn’t be verified . This message appears because apt includes package authentication in order to improve security, and the key is not present. To fix this, click Start menu > System > MX Check Apt GPG and follow the prompts.
- Occasionally, packages will notified install because their install scripts fail one or more safety checks; for instance, a package might try to overwrite a file that is part of another package, or require downgrading another package due to dependencies. If you have an install or upgrade that is stuck on one of these errors, it is called a broken package. To fix this, click on the Broken packages entry in the left panel. Highlight the package and try first to fix the problem by clicking Edit>Fix Broken Packages. If that is not successful, then right-click the package to uninstall it.
- Should you uninstall? Occasionally, conflicts in package dependencies can cause the APT system to require the uninstallation of a large number of important packages in order to install some other package. This is rare with the default configuration, but becomes increasingly likely as you add unsupported repositories. BE VERY ATTENTIVE whenever installing a package would require that others be removed! If a large number of packages are going to be removed, you may want to investigate another method of installing this application.
Should you keep? When upgrading, you may sometimes be informed that a new configuration file is available for a certain package, and be asked whether you want to install the new version or keep your current version.
- If the package in question is from an MX repository, it is recommended that you “install the maintainer’s version”
- Otherwise, answer “keep the current version” (N), which is also the default choice.