The Linux Command Line Second Internet Edition William E. Shotts, Jr. A LinuxCommand.org Book Copyright ©2008-2013, William E. Shotts, Jr. This work is licensed under the Creative Commons Attribution-Noncommercial-No De- rivative Works 3.0 United States License. To view a copy of this license, visit the link above or send a letter to Creative Commons, 171 Second Street, Suite 300, San Fran- cisco, California, 94105, USA. Linux® is the registered trademark of Linus Torvalds. All other trademarks belong to their respective owners. This book is part of the LinuxCommand.org project, a site for Linux education and advo- cacy devoted to helping users of legacy operating systems migrate into the future. You may contact the LinuxCommand.org project at http://linuxcommand.org. This book is also available in printed form, published by No Starch Press and may be purchased wherever fine books are sold. No Starch Press also offers this book in elec- tronic formats for most popular e-readers: http://nostarch.com/tlcl.htm Release History Version Date Description 13.07 July 6, 2013 Second Internet Edition. 09.12 December 14, 2009 First Internet Edition. 09.11 November 19, 2009 Fourth draft with almost all reviewer feedback incorporated and edited through chapter 37. 09.10 October 3, 2009 Third draft with revised table formatting, partial application of reviewers feedback and edited through chapter 18. 09.08 August 12, 2009 Second draft incorporating the first editing pass. 09.07 July 18, 2009 Completed first draft. Table of Contents Introduction....................................................................................................xvi Why Use The Command Line?.....................................................................................xvi What This Book Is About..............................................................................................xvii Who Should Read This Book.......................................................................................xvii What's In This Book.....................................................................................................xviii How To Read This Book..............................................................................................xviii Prerequisites............................................................................................................xix Why I Don't Call It “GNU/Linux”...........................................................................xix Acknowledgments..........................................................................................................xx Your Feedback Is Needed!............................................................................................xx What's New In The Second Internet Edition.................................................................xxi Further Reading............................................................................................................xxi Colophon.......................................................................................................................xxi Part 1 – Learning The Shell..............................................................1 1 – What Is The Shell?.....................................................................................2 Terminal Emulators..........................................................................................................2 Your First Keystrokes......................................................................................................2 Command History.......................................................................................................3 Cursor Movement.......................................................................................................3 A Few Words About Mice And Focus....................................................................3 Try Some Simple Commands..........................................................................................4 Ending A Terminal Session..............................................................................................5 The Console Behind The Curtain..........................................................................5 Summing Up....................................................................................................................5 Further Reading...............................................................................................................6 2 – Navigation...................................................................................................7 Understanding The File System Tree..............................................................................7 The Current Working Directory........................................................................................7 Listing The Contents Of A Directory................................................................................8 Changing The Current Working Directory.......................................................................9 Absolute Pathnames..................................................................................................9 Relative Pathnames...................................................................................................9 Some Helpful Shortcuts............................................................................................11 Important Facts About Filenames........................................................................11 i Summing Up..................................................................................................................12 3 – Exploring The System.............................................................................13 More Fun With ls...........................................................................................................13 Options And Arguments............................................................................................14 A Longer Look At Long Format.................................................................................16 Determining A File's Type With file................................................................................17 Viewing File Contents With less....................................................................................17 What Is “Text”?.....................................................................................................17 Less Is More........................................................................................................19 A Guided Tour................................................................................................................19 Symbolic Links...............................................................................................................23 Hard Links.....................................................................................................................24 Summing Up..................................................................................................................24 Further Reading.............................................................................................................24 4 – Manipulating Files And Directories........................................................25 Wildcards.......................................................................................................................25 Character Ranges................................................................................................27 Wildcards Work In The GUI Too..........................................................................27 mkdir – Create Directories.............................................................................................28 cp – Copy Files And Directories....................................................................................28 Useful Options And Examples..................................................................................29 mv – Move And Rename Files......................................................................................30 Useful Options And Examples..................................................................................30 rm – Remove Files And Directories...............................................................................31 Useful Options And Examples..................................................................................31 Be Careful With rm!.............................................................................................32 ln – Create Links............................................................................................................33 Hard Links................................................................................................................33 Symbolic Links..........................................................................................................33 Let's Build A Playground................................................................................................34 Creating Directories..................................................................................................34 Copying Files............................................................................................................34 Moving And Renaming Files.....................................................................................35 Creating Hard Links..................................................................................................37 Creating Symbolic Links...........................................................................................38