Nearly every distribution now includes a convenient update mechanism. SUSE ships one as part of YaST, and Red Hat uses an application called up2date that connects to the Red Hat Network. Debian, of course, has the apt-get utility described in the previous section. There are other tools out there, but you'll have to install them first. Usually there's no reason to go to all that trouble.
Figure 12-1. KPackage package manager
The update systems are designed to be ultra-simple and therefore are mostly intuitive to use. We will briefly introduce two here: YOU, which comes from the SUSE world, and ZENworks, which comes from the Red Hat world.
12.3.1. YaST Online Update: Automated Updates
YOU ("YaST Online Update") is SUSE's automated update tool. The service is free to use (i.e., it is not a subscription-based service). You run it whenever you feel like it (but doing it regularly might be a good idea if you plan to use such a tool at all). YOU is integrated into the YaST system administration tool; in the Software section, you'll find the Online Update icon. Click this, and the online update screen will appear. At first it is empty, because it needs to load the list of available servers. This can change dynamically over time. You can browse the drop-down list "Installation source" to choose a location that is close to you network-wise.
If you check the checkbox Manually Select Patches and click Next, you will, after a period of time during which the list of updated packages is loaded, be taken to another page (see Figure 12-2) where you can select the packages to update. Those updates that are relevant to you (in other words, that apply to packages you have installed) are already checked. It might still be a good idea to browse down the list, though, because YOU even gets you some packages that are, for legal reasons, not on the installation media. For example, the package fetchmsttfonts lets you download and install TrueType fonts provided by Microsoft (isn't that ironic?). Drivers for various WLAN cards are another example of packages that are only available via the online update. Because these do not update existing packages, they are never checked by default initially, so you may want to choose the manual update selection at least once and check them.
Figure 12-2. Manual package selection in YOU
If you do not check the Manually Select Patches box, the update selection step will be skipped, and the update will be performed immediately.
Another nice little gadget that comes with YOU is the SUSE Watcher. This is a panel applet for your KDE desktop that monitors the package update sites and alerts you when security patches are available by switching into a red ball (see Figure 12-3). Right-clicking that ball opens a context menu that lets you start the online update.
Figure 12-3. SUSE Watcher indicates available security patches
12.3.2. Red Carpet and ZENworks Linux Management: Alternative Package Management Tools
This section looks at another tool for automated update management, called Red Carpet (now part of the ZENworks Linux Management tools from Novell), and explains some of the advantages of different approaches to package management.
Originally developed as an updater for GNOME desktop software, Red Carpet is currently distributed by Novell as part of SUSE Linux distributions and is also available from other sources as a standalone system updater. It can install updates from a variety of servers, including apt repositories and ZENworks servers. Administrators of several flavors of Linux will appreciate having the Red Carpet tools on all their systems, because they provide a consistent interface and command set that abstracts away the package management quirks of individual distributions.
The client side of the package system consists of a daemon (rcd, soon to be changed to zmd), a command-line interface (rug), and a graphical interface. All three of these pieces are free software, although Novell sells a proprietary server application as part of its overall software management suite. The server side is designed for very large, complex organizations and won't be covered here, but we will cover a free alternative for software distribution, Open Carpet.
The ZENworks system distributes Linux software divided into channels, like television shows. Each channel contains a group of individual RPM packages that are related in some way: core operating system, for example, or games. Each package is also assigned a section, such as Productivity or Multimedia, to help you find applications that perform a particular task. You can subscribe to channels the way you would with cable television, so that they can show only software you are interested in. This is particularly useful when there are multiple channels offering different versions of the same application, such as one for the stable branch of Evolution, and one for unstable developer snapshots.
Red Carpet, like other tools, will handle all dependency checking for you: if you try to install a new version of Evolution, and it requires that you upgrade gtkhtml, the program will offer to upgrade that as well. Similarly, if you try to remove software that is required, Red Carpet will warn you that, to keep a clean package database, it will be removing everything upstream from that. For example, if you try to remove the gtk+ package, you'll also have to tear out most of your GNOME desktop tools, which almost universally require that library.
126.96.36.199. Installing Red Carpet
You can download Red Carpet RPM packages from ftp://ftp.novell.com or from your Linux distribution's web site. You may also wish to check http://rpmfind.net or http://open-carpet.org for additional sources. You will need the daemon package rcd or zmd and at least one of the rug (command-line) or Red Carpet (GUI) interface tools. The packages have few dependencies, so you should be able to install them no trouble using the command rpm -Uvh.
188.8.131.52. Using the Red Carpet GUI
The Red Carpet graphical update tool can be invoked either from a menu or with the red-carpet command. When you first start it, it will tell you that there are no updates available, because you have not subscribed to any channels. To change your channel subscriptions, click the Channels button and select the items you want.
Once you have subscribed to channels, the start screen of Red Carpet will display new versions of packages you already have installed, if any are available. Each update is displayed with its name, the version you have and the version of the updated package, plus a recommendation as to how important that update is, ranging from "minor" for small enhancements to "urgent" and "necessary" for more important bugs such as security problems.
To install updates, select the packages you want to update and click the Mark for Installation button, or just click Update All. Then, click the Run Now button. Red Carpet will ask you to confirm the operation, and then perform it.
Near the top of the Red Carpet window is a set of tabsInstalled Software, Available Software, and Searchthat let you see longer lists of software. The first one lists software you already have, the second lists software you don't have, and the third displays all the software that the system knows about whether it's installed or not. In all three cases, you can filter out software by channels and sections, search for specific words in the package name and description, or just show the whole list.
You can mark any package for installation or removal in any of the first four tabs. Actions you have decided to take are listed in the left side of the screen and, in greater detail, in the Pending Actions tab. Only when you click Run Now and confirm all the actions you want to perform will the application remove or install software.
Once you've run a transaction or two, click the History tab to see them listed. This can be very useful if something breaks after a particular software change, and you want to know what you need to undo.
If you're not satisfied with the download performance you get, or with the software available to you, select Edit Services and add or remove servers. You can even use several services at once, for the maximum variety of software. You'll find a list of additional services at http://open-carpet.org.
184.108.40.206. Using the rug command
Once you understand the general zmd concepts, you may find it more convenient to run updates at the command line with rug. Each command consists of rug followed by an action and any option flags or arguments. All actions also have convenient shorthand notations, which we won't use here, but which you can find in the manpages.
Note that, as with all package management systems, most rug actions will require root privileges.
The first action you'll want to use is rug list-updates, which displays a list of available updates. If you want to install them, you can then run rug update. To search for software, use rug search followed by a package name or name fragment. For these and all other rug actions, you can get detailed help by running the command rug action --help. A complete list of actions is available in the manpage and as the output of the command rug help.
More advanced commands for rug include package locking , which lets you mark certain packages as not upgradeable. To add a lock, use rug lock-add packagename. Locks are listed numerically with the rug lock-list command, and deleted using the rug lock-delete locknumber command.
Other actions let you check dependencies. For example, rug what-requires item tells you what software requires a particular piece of software. You can check dependencies on entire packages, on libraries, commands, or almost anything else. For example:
system:/root # rug what-requires libusb S | Channel | Package | Version | libusb Version --+--------------+-------------------+------------------+---------------- | suse-92-i586 | ctapi-cyberjack | 1.0.0-173.1 | (any) i | suse-92-i586 | pcsc-cyberjack | 1.1.1-245.1 | (any) v | suse-92-i586 | pcsc-etoken | 1.1.1-245.1 | (any)
In this example, we see what packages make use of the libusb library. The first column, S, represents the status of the packages in the list. The i next to pcsc-cyberjack denotes that the package is installed. The spaces next to the other packages let us know that they are not installed, and a v indicates that a different version of the package is installed. The second column notes the channel from which the package comes, the third and fourth the package and its version, and the last shows which version of the library is required by the package. In this case, all three packages are content with any version of libusb.
One side effect of being able to check dependencies at a finer level than packages is that you can use the rug solvedeps command to install a library without having to worry about versions or packages. For example, if an application you are trying to install demands libfoo greater than 1.5, you can ask it to solve the problem for you with the command rug solvedeps "libfoo > 1.5". You can also tell solvedeps to avoid a package, library, or binary by placing an exclamation point in front of it: rug solvedeps "!libfoo" "frob > 2.3". If it is possible to install frob Version 2.3 or greater without installing libfoo, it will do so.
Finally, you can access multiple services through rug just like you can with the GUI. Use the rug service-add command, followed by the URL for the service. Several services are listed at http://open-carpet.org.
220.127.116.11. Multiple users
Imagine that you are a system administrator and want to update several systems, but that you don't have root access to all of them. How can you do it? During your system install, install zmd and configure it to recognize you as a remote user. Then, even when the root password changes, you can still install security updates.
To add a user, use the command rug user-add username or, in the GUI, select Edit Users. You will need to enter a password and select privileges for the user you are creating. Note that these usernames and passwords are totally distinct from system logins.
You can grant the following privileges:
Once you have created a user account with the daemon, you can let that user update the system and maintain its software without having to grant them full access to the data on the machine.
To disable remote user connections, use the command rug set-prefs remote-enabled false.
To access a remote daemon using the Red Carpet GUI, select File Connect to Daemon and enter the address of the remote server. To access a remote daemon using rug, use the --host flag to set the host. Note that the default port for listening is 505.
18.104.22.168. Operating an update server
Large businesses often want to keep software updates within their firewalls and completely under their control. To do that, they use enterprise-class upgrade servers with sophisticated interfaces and multiple levels of administrator privileges. That's not the kind of update server we're covering here. If you're shipping a few updates to a few systems, or if you're a developer shipping software and want to make it easy to install and update, you don't need a really complicated system. You just want to make sure that the beta testers have the latest version.
Open Carpet is a free server for HTTP, FTP, and Red Carpet access to packages and package metadata. That means that anyone with a web browser can also download the files and install them by hand, just like with a regular file server, but in addition, Red Carpet users can update and resolve dependencies automatically. In some places it's a little rough around the edges, but it works nicely for those willing to fiddle with configuration files a little bit.
To set up your own server, install open-carpet and libredcarpet-python, available at http://open-carpet.organd of course through the site's own official Open Carpet service. The packages provided contain sample configuration files, normally installed to /usr/share/doc/packages/open-carpet/sample/. Edit the server.conf file first. It's simple enough: enter a name for the server, your email address, and so forth. At the end, it points to a channel directory. Create that directory, put packages in it, and run the open-carpet command. If all goes well, you've got a server. To ship updates, just copy them to the channel directories and run the script again.