1.Introduction to Linux – A Hands on Guide PDF

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Introduction to Linux

A Hands on Guide Machtelt Garrels Garrels.be

1.27 Edition Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008 Machtelt Garrels 20080606

Introduction to Linux

Table of Contents Introduction.........................................................................................................................................................1 1. Why this guide?...................................................................................................................................1 2. Who should read this book?.................................................................................................................1 3. New versions and availability..............................................................................................................1 4. Revision History..................................................................................................................................2 5. Contributions.......................................................................................................................................3 6. Feedback..............................................................................................................................................3 7. Copyright information.........................................................................................................................3 8. What do you need?...............................................................................................................................4 9. Conventions used in this document.....................................................................................................4 10. Organization of this document...........................................................................................................5 Chapter 1. What is Linux?.................................................................................................................................7 1.1. History..............................................................................................................................................7 1.1.1. UNIX.......................................................................................................................................7 1.1.2. Linus and Linux.......................................................................................................................8 1.1.3. Current application of Linux systems.....................................................................................9 1.2. The user interface..............................................................................................................................9 1.2.1. Is Linux difficult?....................................................................................................................9 1.2.2. Linux for non-experienced users...........................................................................................10 1.3. Does Linux have a future?..............................................................................................................10 1.3.1. Open Source..........................................................................................................................10 1.3.2. Ten years of experience at your service................................................................................11 1.4. Properties of Linux.........................................................................................................................12 1.4.1. Linux Pros.............................................................................................................................12 1.4.2. Linux Cons............................................................................................................................13 1.5. Linux Flavors..................................................................................................................................14 1.5.1. Linux and GNU.....................................................................................................................14 1.5.2. GNU/Linux............................................................................................................................15 1.5.3. Which distribution should I install?......................................................................................15 1.6. Summary.........................................................................................................................................16 1.7. Exercises.........................................................................................................................................16 Chapter 2. Quickstart.......................................................................................................................................18 2.1. Logging in, activating the user interface and logging out..............................................................18 2.1.1. Introduction...........................................................................................................................18 2.1.2. Graphical mode.....................................................................................................................18 2.1.3. Text mode..............................................................................................................................20 2.2. Absolute basics...............................................................................................................................21 2.2.1. The commands......................................................................................................................21 2.2.2. General remarks....................................................................................................................21 2.2.3. Using Bash features...............................................................................................................22 2.3. Getting help.....................................................................................................................................23 2.3.1. Be warned..............................................................................................................................23 2.3.2. The man pages.......................................................................................................................23 2.3.3. More info...............................................................................................................................25 2.4. Summary.........................................................................................................................................28 2.5. Exercises.........................................................................................................................................29 i

Introduction to Linux

Table of Contents Chapter 2. Quickstart 2.5.1. Connecting and disconnecting...............................................................................................29 2.5.2. Passwords..............................................................................................................................29 2.5.3. Directories.............................................................................................................................30 2.5.4. Files.......................................................................................................................................30 2.5.5. Getting help...........................................................................................................................31 Chapter 3. About files and the file system......................................................................................................32 3.1. General overview of the Linux file system.....................................................................................32 3.1.1. Files.......................................................................................................................................32 3.1.2. About partitioning.................................................................................................................33 3.1.3. More file system layout.........................................................................................................37 3.2. Orientation in the file system..........................................................................................................40 3.2.1. The path.................................................................................................................................40 3.2.2. Absolute and relative paths...................................................................................................41 3.2.3. The most important files and directories...............................................................................41 3.2.4. The most important configuration files.................................................................................44 3.2.5. The most common devices....................................................................................................46 3.2.6. The most common variable files...........................................................................................47 3.3. Manipulating files...........................................................................................................................48 3.3.1. Viewing file properties..........................................................................................................48 3.3.2. Creating and deleting files and directories............................................................................50 3.3.3. Finding files...........................................................................................................................53 3.3.4. More ways to view file content.............................................................................................57 3.3.5. Linking files..........................................................................................................................58 3.4. File security.....................................................................................................................................60 3.4.1. Access rights: Linux's first line of defense............................................................................60 3.4.2. The tools................................................................................................................................62 3.5. Summary.........................................................................................................................................67 3.6. Exercises.........................................................................................................................................68 3.6.1. Partitions................................................................................................................................68 3.6.2. Paths......................................................................................................................................68 3.6.3. Tour of the system.................................................................................................................69 3.6.4. Manipulating files..................................................................................................................69 3.6.5. File permissions.....................................................................................................................69 Chapter 4. Processes.........................................................................................................................................71 4.1. Processes inside out........................................................................................................................71 4.1.1. Multi-user and multi-tasking.................................................................................................71 4.1.2. Process types.........................................................................................................................71 4.1.3. Process attributes...................................................................................................................73 4.1.4. Displaying process information.............................................................................................74 4.1.5. Life and death of a process....................................................................................................76 4.1.6. SUID and SGID.....................................................................................................................78 4.2. Boot process, Init and shutdown.....................................................................................................80 4.2.1. Introduction...........................................................................................................................80 4.2.2. The boot process....................................................................................................................80 4.2.3. GRUB features......................................................................................................................80 ii

Introduction to Linux

Table of Contents Chapter 4. Processes 4.2.4. Init.........................................................................................................................................81 4.2.5. Init run levels.........................................................................................................................83 4.2.6. Shutdown...............................................................................................................................84 4.3. Managing processes........................................................................................................................84 4.3.1. Work for the system admin...................................................................................................84 4.3.2. How long does it take?..........................................................................................................85 4.3.3. Performance...........................................................................................................................86 4.3.4. Load.......................................................................................................................................86 4.3.5. Can I do anything as a user?..................................................................................................86 4.4. Scheduling processes......................................................................................................................91 4.4.1. Use that idle time!.................................................................................................................91 4.4.2. The sleep command...............................................................................................................91 4.4.3. The at command....................................................................................................................92 4.4.4. Cron and crontab...................................................................................................................92 4.5. Summary.........................................................................................................................................94 4.6. Exercises.........................................................................................................................................95 4.6.1. General..................................................................................................................................95 4.6.2. Booting, init etc.....................................................................................................................95 4.6.3. Scheduling.............................................................................................................................96 Chapter 5. I/O redirection................................................................................................................................97 5.1. Simple redirections.........................................................................................................................97 5.1.1. What are standard input and standard output?......................................................................97 5.1.2. The redirection operators.......................................................................................................97 5.2. Advanced redirection features......................................................................................................100 5.2.1. Use of file descriptors..........................................................................................................100 5.2.2. Examples.............................................................................................................................101 5.3. Filters............................................................................................................................................101 5.3.1. More about grep..................................................................................................................102 5.3.2. Filtering output....................................................................................................................102 5.4. Summary.......................................................................................................................................103 5.5. Exercises.......................................................................................................................................103 Chapter 6. Text editors...................................................................................................................................105 6.1. Text editors...................................................................................................................................105 6.1.1. Why should I use an editor?................................................................................................105 6.1.2. Which editor should I use?..................................................................................................105 6.2. Using the Vim editor.....................................................................................................................106 6.2.1. Two modes..........................................................................................................................106 6.2.2. Basic commands..................................................................................................................107 6.2.3. The easy way.......................................................................................................................108 6.3. Linux in the office.........................................................................................................................108 6.3.1. History.................................................................................................................................108 6.3.2. Suites and programs............................................................................................................108 6.3.3. Remarks...............................................................................................................................109 6.4. Summary.......................................................................................................................................109 6.5. Exercises.......................................................................................................................................110 iii

Introduction to Linux

Table of Contents Chapter 7. Home sweet /home.......................................................................................................................111 7.1. General good housekeeping..........................................................................................................111 7.1.1. Introduction.......................................................................