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IBM developerWorks : Linux
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Porting Perl To Python Porting legacy Perl to Python can be a daunting task. In this article, learn some of the theory behind dealing with legacy code, including what not to do. Resizing Linux partitions, Part 2: Advanced resizing Linux systems are often installed on multiple partitions, each of which has a fixed size. As your needs change, though, it is often necessary to resize partitions to suit your changing needs. Several tools exist to do this in Linux, but there are a number of potential pitfalls and restrictions that can make the task more difficult than it might at first seem. This article covers advanced partition resizing issues, including using Logical Volume Management (LVM) features, troubleshooting, and alternatives to partition resizing. Part 1 of this series covered basic partition resizing. Avoiding memory leaks in POSIX thread programming POSIX thread (pthread) programming defines a standard set of C programming language types, functions, and constants--and pthreads provide a powerful tool for thread management. To use pthreads to the fullest, you'll want to avoid the common mistakes. One common mistake is forgetting to join joinable threads, which can create memory leaks and cause extra work. In this tips-oriented article, learn the basics of POSIX threads, see how to identify and detect thread memory leaks, and get solid advice for avoiding them. Learn Linux, 101: Maintain the integrity of filesystems Learn how to check the integrity of your Linux filesystems, monitor free space, and fix simple problems. Use the material in this article to study for the Linux Professional Institute (LPI) 101 exam for Linux system administrator certification--or just to check your filesystems and keep them in good working order, especially after a system crash or power loss. Learn Linux, 101: A roadmap for LPIC-1 Use this roadmap to find IBM developerWorks articles that will help you learn and review basic Linux tasks. And if you're also pursuing professional certification as a Linux system administrator, these articles can help you study for the Linux Professional Institute Certification (LPIC) exam 101 and exam 102. This roadmap is organized according to the 43 objectives in the 101 and 102 exams, which you are required to pass for LPI level 1 certification. Ubuntu Linux solution stack implementation, Part 2: Solution stack download and installation Learn how to download and install Rational Application Developer for WebSphere, DB2 Express-C, and a few other third party packages to get the solution stack up and running. This 4-part demo series shows you how to implement the solution stack (Rational Application Developer, WebSphere Application Server, and DB2 Express-C) on Ubuntu Linux, and how to integrate them in a Java application. Ubuntu Linux solution stack implementation, Part 3: Demo application Learn how to configure and setup Rational Application Developer, create a WebSphere profile, create a database in DB2 Express-C, and perform a test run on the solution stack. This 4-part demo series shows you how to implement the solution stack (Rational Appli-ation Developer, WebSphere Application Server, and DB2 Express-C) on Ubuntu Linux, and how to integrate them in a Java application. Ubuntu Linux solution stack implementation, Part 4: Solution stack setup and integration Part 4 of this demo series shows you how to import the Java servlet application files into the Rational Application Developer workspace, edit a few classes, and deploy the application on a WebSphere Application Server. Finally, you get to see the solution stack work in a real life scenario. This 4-part demo series shows you how to implement the solution stack (Rational Application Developer, WebSphere Application Server, and DB2 Express-C) on Ubuntu Linux, and how to integrate them in a Java application. User space memory access from the Linux kernel As the kernel and user space exist in different virtual address spaces, there are special considerations for moving data between them. Explore the ideas behind virtual address spaces and the kernel APIs for data movement to and from user space, and learn some of the other mapping techniques used to map memory. Resizing Linux partitions, Part 1: Basics Linux systems are often installed on multiple partitions, each of which has a fixed size. As your needs change, though, it is often necessary to resize partitions to suit your changing needs. Several tools exist to do this in Linux, but there are a number of potential pitfalls and restrictions that can make the task more difficult than it might seem at first. This article guides you through the task of resizing Linux partitions, beginning with basic preparations and moving on to common resizing scenarios using graphical user interface (GUI) tools. High availability with the Distributed Replicated Block Device The 2.6.33 Linux kernel has introduced a useful new service called the Distributed Replicated Block Device (DRBD). This service mirrors an entire block device to another networked host during run time, permitting the development of high-availability clusters for block data. Explore the ideas behind the DRBD and its implementation in the Linux kernel. Migrate your Linux application to the Amazon cloud, Part 2: Improving application reliability In this article, the second in a series on migrating a Linux application to the Amazon cloud, learn how to make your application more robust by employing a load balancer and persistent disk. You'll use multiple servers and learn how to safely back up your data. Speaking UNIX: Get to know Ksplice Ksplice applies kernel patches on-the-fly - no reboot required - in a fraction of a second. Here's a hands-on guide to performing painless system updates. Ubuntu Linux solution stack implementation, Part 1: Introduction to the UNIX environment Learn how to download and install a Ubuntu image and then go through some basic shell commands to help you navigate through the UNIX environment. This is part 1 of a 4 part demo series to show you how to implement a solution stack (Rational Application Developer, WebSphere Application Server, and DB2 Express-C) on Ubuntu Linux, as well as how to integrate them in a Java application. Add your own GIMP features The GNU Image Manipulation Program (GIMP) is a robust application for editing and manipulating digital images. Because it's open source software, any developer is allowed to modify and extend it with even more features. In this article, you will learn how to get started with the GIMP code, how to build the project from the Git repositories, and how to find your way around the code tree. And you will build an example application that creates a whole new painting tool for the program. Distributed data processing with Hadoop, Part 3: Application development With configuration, installation, and the use of Hadoop in single- and multinode architectures under your belt, you can now turn to the task of developing applications within the Hadoop infrastructure. This final article in the series explores the Hadoop APIs and data flow and demonstrates their use with a simple mapper and reducer application. Migrate your Linux application to the Amazon cloud, Part 1: Initial migration Cloud computing and Infrastructure as a Service (IaaS) are well documented, but what's often not discussed is how to get a running application into a cloud environment. In this series, discover how to move an application into the cloud and take advantage of the features this setup has to offer. In Part 1, see a straight migration from one physical server to a cloud server. Learn Linux, 101: Create partitions and filesystems Learn how to create partitions on a disk drive and how to format them for use on a Linux system as swap or data space. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn about partitions and Linux filesystems for your own use. Learn Linux, 101: Find and place system files Learn the correct location for files under the Filesystem Hierarchy Standard (FHS) on a Linux system and learn how to find important files and commands. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to explore file organization and management. Distributed data processing with Hadoop, Part 2: Going further The first article in this series showed how to use Hadoop in a single-node cluster. This article continues with a more advanced setup that uses multiple nodes for parallel processing. It demonstrates the various node types required for multinode clusters and explores MapReduce functionality in a parallel environment. This article also digs into the management aspects of Hadoop -- both command line and Web based. Continuous integration with Buildbot The days of cowboy coding are long gone at most organizations, replaced by a renewed interest in generating quality software. Continuous integration (CI) testing is a vital component in the practice of agile programming techniques that lead to high-quality software. Learn the theory and practice of CI testing by exploring Buildbot, an open source CI system written in Python. Learn Linux, 101: Create and change hard and symbolic links Learn how to create and manage hard and symbolic links to files on your Linux system. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to explore the differences between hard and soft, or symbolic, links and the best ways to link to files, as opposed to copying files. Enable multipath SAN booting with DS8000 and DMMP Booting servers from storage area networks with multiple paths can provide significant benefits for the complex, modern data center environment -- benefits such as improving availability and increasing your reach when it comes to easier management and maintenance and in providing reliability. To boot your Linux system from a SAN device, you'll need to set up a SAN boot operating system to your storage with multipath driver support; that's where this article comes in. The author will walk you through setting up a SAN-boot Linux system on the IBM System Storage DS8000 with the multipath function supported by the Device-Mapper MultiPath (DMMP) feature. [Editor's note: The article is updated per the author's comment below.] Distributed data processing with Hadoop, Part 1: Getting started This article -- the first in a series on Hadoop -- explores the Hadoop framework, including its fundamental elements, such as the Hadoop file system (HDFS), and node types that are commonly used. Learn how to install and configure a single-node Hadoop cluster, and delve into the MapReduce application. Finally, discover ways to monitor and manage Hadoop using its core Web interfaces. Learn Linux, 101: Debian package management Learn how to install, upgrade, and manage packages on your Linux system. This article focuses on the Advanced Packaging Tool, or APT, which is the package management system used by Debian and distributions derived from Debian, such as Ubuntu. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to explore the best ways to add new software and keep your system current. Learn Linux, 101: RPM and YUM package management Learn how to install, upgrade and manage packages on your Linux system. This article focuses on the Red Hat Package Manager (RPM) developed by Red Hat, as well as the Yellowdog Updater Modified (YUM) originally developed to manage Red Hat Linux systems at Duke University's Physics department. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to explore the best ways to add new software and keep your system current. Ceph: A Linux petabyte-scale distributed file system Linux continues to invade the scalable computing space and, in particular, the scalable storage space. A recent addition to Linux's impressive selection of file systems is Ceph, a distributed file system that incorporates replication and fault tolerance while maintaining POSIX compatibility. Explore the architecture of Ceph and learn how it provides fault tolerance and simplifies the management of massive amounts of data. Linux on 4KB-sector disks: Practical advice Starting in December 2009, hard disk manufacturers began introducing disks that use 4096-byte sectors rather than the more common 512-byte sectors. Although this change is masked by firmware that breaks the 4096-byte physical sectors into 512-byte logical sectors for the benefit of the operating system, the use of larger physical sectors has implications for disk layout and system performance. This article examines these implications, including benchmark tests illustrating the likely real-world effects on some common Linux file systems. As disks with 4096-byte sectors become more common throughout 2010 and beyond, strategies for coping with these new disks will become increasingly important. Open source in a new light So you've got to cut costs, but you're not a manager. You're a software developer, or a power user, or just someone who needs to keep the bottom line healthy enough to support your salary. These are ideal situations for introducing open source software solutions into your environment. That might sound like you'll spend the next three weeks learning to program or write makefiles, but it's just not so. Read on and see how open source is a flexible, usable approach to efficiency in your work environment. Migrate to GRUB 2 The tools used to boot Linux are changing. Specifically, the Grand Unified Bootloader (GRUB) is now officially in maintenance mode only, and GRUB's developers have abandoned the original GRUB in favor of an entirely rewritten package, known as GRUB 2. Discover GRUB 2's new capabilities and how to use it. Learn Linux, 101: Boot managers Learn how to choose and configure a boot manager for your Linux system. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Anatomy of Linux Kernel Shared Memory Linux as a hypervisor includes a number of innovations, and one of the more interesting changes in the 2.6.32 kernel is Kernel Shared Memory (KSM). KSM allows the hypervisor to increase the number of concurrent virtual machines by consolidating identical memory pages. Explore the ideas behind KSM (such as storage de-duplication), its implementation, and how you manage it. Monitor Linux file system events with inotify Use inotify when you need efficient, fine-grained, asynchronous monitoring of Linux file system events. Use it for user-space monitoring for security, performance, or other purposes. Kernel APIs, Part 3: Timers and lists in the 2.6 kernel The Linux kernel includes a variety of APIs intended to help developers build simpler and more efficient driver and kernel applications. Two of the more common APIs that can be used for work deferral are the list management and timer APIs. Discover these APIs, and learn how to develop kernel applications with timers and lists. Learn Linux, 101: Manage shared libraries Learn how to determine which shared libraries your Linux executable programs depend on and how to load them. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Scripting the Vim editor, Part 5: Event-driven scripting and automation Why repeat yourself? You can configure Vimâ€™s comprehensive event model to execute time-saving scripts whenever particular editing events -- such as loading a file or switching between editor modes -- occur. This article, the fifth in a series, describes how events work in Vim, explores a selection of useful event types, and then gets you started with attaching specific scripts to particular events. The end result is a more automated workflow configured precisely to your needs. Kernel APIs, Part 2: Deferrable functions, kernel tasklets, and work queues For high-frequency threaded operations, the Linux kernel provides tasklets and work queues. Tasklets and work queues implement deferrable functionality and replace the older bottom-half mechanism for drivers. This article explores the use of tasklets and work queues in the kernel and shows you how to build deferrable functions with these APIs. Learn Linux, 101: Hard disk layout Learn how to design a partition layout for disks on a Linux system. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Kernel APIs, Part 1: Invoking user-space applications from the kernel The Linux system call interface permits user-space applications to invoke functionality in the kernel, but what about invoking user-space applications from the kernel? Explore the usermode-helper API, and learn how to invoke user-space applications and manipulate their output. Kernel command using Linux system calls Linux system calls -- we use them every day. But do you know how a system call is performed from user-space to the kernel? Explore the Linux system call interface (SCI), learn how to add new system calls (and alternatives for doing so), and discover utilities related to the SCI. [This article has been updated to reflect coding changes for kernels 2.6.18 and later. -Ed.] Scripting the Vim editor, Part 4: Dictionaries A dictionary is a container data structure that offers different optimizations and trade-offs from a list. In particular, in a dictionary the order of the elements stored is irrelevant and the identity of each element is explicit. In this fourth article in a series introducing Vimscript, Damian Conway introduces you to dictionaries, including an overview of their basic syntax and many functions. He concludes with several examples that illustrate the use of dictionaries for more efficient data processing and cleaner code. Learn Linux, 101: File editing with vi Learn how to use the vi editor, found on almost every UNIX and Linux system. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Using QEMU for cross-platform development One of Linux's strengths is its cross-platform nature: you can run it on x86, x86-64, SPARC, PowerPC, and many other central processing units (CPUs). This wealth of hardware choices poses a challenge for software developers, though. Ensuring that software compiles, and runs correctly, on all platforms can be difficult. The use of the QEMU package can help ease this burden. QEMU is a machine emulator that supports a wide range of CPUs, so you can run PowerPC software on an x86 computer, x86-64 software on an SPARC computer, or what have you. This facility is particularly useful for programmers who need to test software's endianness compatibility or check other CPU-specific features. QEMU also enables you to run different operating systems entirely, so that you can test a program's ability to compile and run under FreeBSD, Solaris, or even Microsoft Windows without shutting down Linux. Learn Linux, 101: Search text files using regular expressions Learn how to use regular expressions, and then use them to find things in files on your filesystem. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Learn Linux, 101: Process execution priorities Learn how to set and change process priorities so that applications get as much processing time as they need. You can use this material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Learn Linux, 101: Create, monitor, and kill processes Learn about process management on Linux: how to shuffle processes between foreground and background, find out what's running, kill processes, and keep processes running after you've left for the day. You can use the material in this article to study for the LPI 101 exam for Linux system administrator certification, or just to learn for fun. Virtio: An I/O virtualization framework for Linux The Linux kernel supports a variety of virtualization schemes, and that's likely to grow as virtualization advances and new schemes are discovered (for example, lguest). But with all these virtualization schemes running on top of Linux, how do they exploit the underlying kernel for I/O virtualization? The answer is virtio, which provides an efficient abstraction for hypervisors and a common set of I/O virtualization drivers. Discover virtio, and learn why Linux will soon be the hypervisor of choice. Scripting the Vim editor, Part 3: Built-in lists Vimscript provides excellent support for operating on collections of data, a cornerstone of programming. In this third article in the series, learn how to use Vimscript's built-in lists to ease everyday operations such as reformatting lists, filtering sequences of filenames, and sorting sets of line numbers. You'll also walk through examples that demonstrate the power of lists to extend and enhance two common uses of Vim: creating a user-defined function to align assignment operators, and improving the built-in text completions mechanism. Generate dummy CIM indications for testing on Linux Hardware management using the Common Information Model standard often means that the management application must be capable of listening to and handling the indications that occur at the hardware level. To test the indication listener component of the management application when the planned system hardware is not available during development, you will need dummy indications. This article explains how to generate dummy indications on OpenPegasus CIMOM (Common Information Model Object Manager) using a provider shipped with the OpenPegasus source code. Learn Linux, 101: Text streams and filters There's a lot more to text manipulation than cut and paste, particularly when you aren't using a GUI. Study for the Linux Professional Institute Certification (LPIC) 101 exam, or learn for fun. In this article, Ian Shields introduces you to text manipulation on Linux using filters from the GNU textutils package. By the end of this article, you will be manipulating text like an expert. [The first line of Listing 7 has been corrected, thanks to an alert reader. -Ed.}