Introduction to Linux June 1, 2005 What is Linux? o Linux is a free, Unix-like, multi-user, multitasking operating system. Linux can be acquired for free. Because there is little incentive for profit, Linux programmers are very cooperative and share ideas with one another. Linux derives most of its features from UNIX. Many users may log onto a single Linux system simultaneously. A Linux system may run multiple applications simultaneously.
Why Study Linux (pp. 2-3): o There are many reasons to learn about the Linux operating system. In fact, it will be difficult to earn a living in computing without a through knowledge of Linux. o Linux is used in the following everyday activities: Most Web servers are Linux-based. Most movie special effects are produced on Linux systems. Financial activities, such as stock and banking activities, are conducted on Linux systems. The United States government and military make extensive use of Linux. Universities use Linux-based systems for records, research, communications, etc. o Linux was designed for largely complicated tasks performed in networked environments.
The Advantages of Linux: o Affordability – You pay for technical support, documentation, CD-ROM, but never pay for the software (the code itself). o Stability – If an application crashes in Linux, it does not crash the entire system. o Reliability – Because Linux is open source and many developments are made by users, there is no pressure to release new applications or upgrades by a certain date.
o File System – On the file systems of other operating systems, files are broken into smaller fragments that are stored in multiple locations around a hard disk, which reduces the efficiency. File creation and deletion leads to more fragmentation, which leads to lower hard disk efficiency. o Server Influence – Linux was originally built as a server, not a desktop OS. o Flexibility, Customization, and Configuration – Users may choose from different shells, different GUIs, etc. o Security – Securing Linux may take a little bit of extra knowledge, but that extra knowledge usually leads to a more secure operating system. Because Linux is open source, programmers around the world to develop patches whenever security holes are found. o Multi-user capabilities – Linux is built as a server and thus uses accounts. User configurations can be stored, and upon login, all custom configurations for that user will be loaded. Users are also given a home directory in which personal data may be stored. o Multi-tasking capabilities – Linux has the ability to handle and regulate many processes running at the same time. Linux handles multitasking very well because its memory allocation is designed to keep system lag at a minimum.
The Disadvantages of Linux: o Because you must learn UNIX commands, it takes longer to learn about Linux. o Printed instruction manuals and technical support is much harder to find. o Configuring devices in Linux is generally more difficult. o Linux does not have an abundance of commercial software, such as word-processing software, Internet browsers, and games. o The Linux GUI does not provide as much functionality as the Linux CLI (command line interface).
Linux Distributions (p.15): o Vendors have sold Linux for many years. If Linux is free and open source, why would anyone pay for it? People don’t pay for the software (the code), but they pay for the technical support, the documentation, and the CD-ROM. o Linux has been developed in bits and pieces by many programmers. These bits and pieces must be grouped together in order to use Linux. The time and technical knowledge to do this grouping is beyond most people. Linux distributions are used to alleviate this problem. o Many organizations offer Linux distributions and they differ primarily in the packaging of these bits and pieces. o As we mentioned earlier, many companies release many distributions of Linux. Each distribution is different, so many Linux users try different versions to see which one best fits their needs.
Major Linux Distributions: o RedHat – probably the most popular o Slackware o Debian / GNU o Caldera o SuSE
History of Linux (pp. 14-15): o Because Linux is a derivative of UNIX. Therefore, it is necessary to learn a little history of Linux. UNIX was developed in 1970 and officially released and distributed by AT&T Bell Labs in 1972. o The University of California at Berkeley was one of the users of this 1972 version. They added many new features and released a new version of UNIX, known as the Berkeley Software Distribution (BSD), which remains popular today. o Many other organizations have developed new versions of UNIX through the years. Therefore, there are today many different versions of UNIX.
o All of these versions of UNIX were designed primarily for large computers used at corporations and Universities. As personal desktop computers became popular throughout the 1980s, most people found the PC version of UNIX inadequate. o Developing an effective PC version of UNIX became a personal project for a 21-year old Finnish computer science student named Linus Torvalds. He released the first version of Linux in mid-September 1991. It was so basic that it was released as version 0.01. o He continued to add features to Linux for the next three years. He released the first official version (version 1.0) in March 1994. o Linux grew quickly both in popularity and functionality for two reasons. First, Linux has always been intended to be open source software. This meant that it could be accessed, modified, and enhanced by anyone. Secondly, Linux was widely distributed over the Internet. Therefore, thousands of programmers were able to access, modify, and enhance Linux. o A group of programmers based in North Carolina began to work on a Linux distribution in the summer of 1994. Their goal was to develop a distribution that was easy for common users to use and install. This distribution became Red Hat Linux, the most popular distribution today.