Writing a Java Class to Manage RPM Package Content
Installing a Linux system for the first time is quite straightforward. You can find good and cheap Linux packages on the market that will quickly install themselves. You need only choose some configuration options describing the type of hardware on which you want to install, and that's it.
As time goes on, you will add some new components to your Linux system, and that's where the nightmare may begin. A Linux system is composed of hundreds of components and dynamic libraries. In order to keep your system up and running, you should be careful, since installing a new version of a component may introduce incompatibilities in your system, making it more unstable as time goes on.
Replacing an existing component with a new version at first looks like a trivial task: you just need to pick up a new compiled version of the component, generally available on the Net in a .tgz file (tar + gzip compression), and install it on your system. Some dynamic libraries of the component you just upgraded may already be used by other installed components and might not be compatible with the new version you just installed.
It would be great to have a tool which could report the dependencies of each component installed on your system. Such a tool could tell you the version of Samba (for instance) installed on your system or that you can't install egcs-1.0.2-8 on your system prior to having binutils 2.9 up and running. This tool already exists on Linux—it is called RPM—and is on many existing Linux distributions, including Red Hat, Caldera, SuSE and Linux Mandrake.
RPM stands for Red Hat Package Manager and is described by its creator as “an open packaging system available for anyone to use and works on Red Hat Linux as well as other Linux and UNIX systems” (from the Red Hat installation guide).
Before starting the programming discussion, I will introduce the RPM package manager and give a general overview of it. If you need more information, see Resources for more than 400 pages of interesting details on RPM's history, design, usage and programming.
The diagram in Figure 1 represents the different components involved in the RPM tool. RPM is composed of three main parts:
RPM utilities, which modify the database and packages
The RPM database, located in /var/lib/rpm on Red Hat distributions, is owned by root; it is a mirror of all the packages which are presently installed on your system. The RPM utility accepts various commands which query the database for installed packages, install or update the system with new RPM packages, remove unused packages from the system, and verify and check installed package dependencies. Usually, when a new version of a given component becomes available on the Net, you have two choices:
Look for a tar gzip file containing the sources. Compile the sources on your system, then proceed with installation of the binaries. The given package generally provides a README, a make and make install procedure to help you.
Look for a tar, gzip file containing the binaries, meaning that someone else has already compiled the sources for you on the same kind of computer as yours. Then proceed with installation of the binaries.
Let's say you are interested in installing version 1.9.18 of Samba. First, you should look on the Net for an RPM of the Samba package (instead of a tar, gzip package). Once you have it, type:
rpm -uvh samba-1.9.18p8-50.1.i386.rpm
This command will install (or upgrade) a copy of Samba on your system. It will also check that all dependencies needed by this version of Samba are present on your system. If the rpm command completes with no error messages, you're guaranteed the installed package will be ready to run without trouble at the end of the installation process.
This installation process will also update the RPM database which keeps track of all installed packages on your system and all their dependencies.
So if, six months later, you want to find out which version of Samba is installed on your system, typing the following command:
rpm -q samba
will tell you
samba-1.9.18p8-50.1If you want to remove a package from your system, the RPM utilities will remove the files which were installed on your system during installation.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide