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Linux Shell Scripting Tutorial (LSST) v2.0 Written by Vivek Gite. Copyright 1999-2010 Vivek Gite and its contributors. Some rights reserved. Chapter 1: Quick Introduction to Linux What Is Linux? Who created Linux? Where can I download Linux? How do I Install Linux? Linux usage in everyday life What is Linux Kernel? What is Linux Shell? Unix philosophy But how do you use the shell? What is a Shell Script or shell scripting? Why shell scripting? Chapter 1 Challenges Chapter 2: Getting Started With Shell Programming The bash shell Shell commands The role of shells in the Linux environment Other standard shells Write a simple shell script - "Hello World!" Starting a script with Shebang line (#!) Comments in a script Setting up permissions on a script Execute a script Debug a script Chapter 2 Challenges Chapter 3:The Shell Variables and Environment Variables in shell Assign values to shell variables Default shell variables value Rules for Naming variable name Display the value of shell variables Quoting The export statement Unset shell and environment variables Getting User Input Via Keyboard Perform arithmetic operations Create an integer variable Create the constants variable Bash variable existence check Customize the bash shell environments Recalling command history Path name expansion Create and use aliases The tilde expansion Startup scripts Using aliases Changing bash prompt Setting shell options Setting system wide shell options Chapter 3 Challenges Chapter 4: Conditionals Execution (Decision Making) Bash structured language constructs Test command if structures to execute code based on a condition If..else..fi Nested ifs Multilevel if-then-else The exit status of a command Conditional execution Logical AND && Logical OR || Logical Not ! Conditional expression using [ (portable version) Conditional expression using [[ Numeric comparison String comparison File attributes comparisons Shell command line parameters How to use positional parameters Parameters Set by the Shell Create usage messages Exit command The case statement Dealing with case sensitive pattern Chapter 4 Challenges Chapter 5: Bash Loops The for loop statement Nested for loop statement The while loop statement Use of : to set infinite while loop The until loop statement The select loop statement Exit the select loop statement Using the break statement Using the continue statement Command substitution Chapter 5 Challenges Chapter 6: Shell Redirection Input and Output Standard input Standard output Standard error Empty file creation /dev/null discards unwanted output here documents here strings Redirection of standard error Redirection of standard output Appending redirected output Redirection of both standard error and output Writing output to files Assigns the file descriptor (fd) to file for output Assigns the file descriptor (fd) to file for input Closes the file descriptor (fd) Opening the file descriptors for reading and writing Reads from the file descriptor (fd) Executes commands and send output to the file descriptor (fd) Chapter 6 Challenges Chapter 7: Pipes and Filters Linking Commands Multiple commands Putting jobs in background Pipes How to use pipes to connect programs Input redirection in pipes Output redirection in pipes Why use pipes Filters Chapter 7 Challenges Chapter 8: Traps Signals What is a Process? How to view Processes Sending signal to Processes Terminating Processes Shell signal values The trap statement How to clear trap Include trap statements in a script Use the trap statement to catch signals and handle errors What is a Subshell? Compound command exec command Chapter 8 Challenges Chapter 9: Functions Writing your first shell function Displaying functions Removing functions Defining functions Writing functions Calling functions Pass arguments into a function local variable Returning from a function Shell functions library Source command Recursive function Putting functions in background Chapter 9 Challenges Chapter 10: Interactive Scripts Menu driven scripts Getting information about your system Bash display dialog boxes dialog customization with configuration file A yes/no dialog box An input dialog box A password box A menu box A progress bar (gauge box) The file selection box The form dialog for input Console management Get the name of the current terminal Fixing the display with reset Get screen width and hight with tput Moving the cursor with tput Display centered text in the screen in reverse video Set the keyboard leds Turn on or off NumLock leds Turn on or off CapsLock leds Turn on or off ScrollLock leds Set terminal attributes Display KDE / GTK+ GUI dialog zenity: Shell Scripting with Gnome Shell script create a calendar GUI dialog box Shell script create a file selection GUI dialog box Shell script to send notification to the Gnome notification area Shell script create a list GUI dialog box Shell script create an error message GUI dialog box Shell script create an information message GUI dialog box Shell script create a question message GUI dialog box Shell script create a warning message GUI dialog box kdialog: Shell scripting with KDE notify-send: Send desktop notifications Chapter 10 Challenges To do Work in progress

Introduction This tutorial is a beginners handbook for new Linux users / Sys admins and school students studying Linux or computer science. This book is licensed under "Creative Commons Attribution Noncommercial Share Alike 3.0 Unported". Getting Started We are looking for contributors to help correct typos, enhanced and edit the tutorial. Take the time to read the tutorial. All registered user can edit or post new sections. If you are new to the wiki please check out the excellent Mediawiki editing guide and use the Sandbox for testing purpose. Update : I'm now allowing anonymous user to edit the tutorial. Don't add nasty spam. No point putting in personal details or links, I will remove them and ban your IP. Try and edit in English and please stick to the point! Thank you!! PDF Version You can download a PDF version by visiting this url. Have a Question About Shell Scripting? If you'd like to contact us about helping you with a Linux shell scripting problem just click here to visit our excellent tech support forum. Download Bash Shell The current production versions are Bash 3.x and 4.x. Grab it from the official website. Bash Documentation Bash's standard documentation is substantial; download your own copy or browse it online! You may also find Bash quick reference quite useful. The Bash FAQ, version 4.01, for Bash version 4.0. Bash and friends books Learning the bash Shell: Unix Shell Programming In a Nutshell (O'Reilly) bash Cookbook: Solutions and Examples for bash Users - Cookbooks (O'Reilly) Linux Shell Scripting with Bash (Sams) Mastering Unix Shell Scripting: Bash, Bourne, and Korn Shell Scripting for Programmers, System Administrators, and UNIX Gurus (Wiley) Learning the vi and Vim Editors (O'Reilly) Bash IDE vim or vi. gedit (see how to install gedit plugins). GNU emacs. Learn Bash (tutorial links) Bash shell script directory Top 10 Best Cheat Sheets and Tutorials for Linux / UNIX Commands Advanced Bash-Scripting Guide Command-line Fu < The best UNIX commands on the web Another website with best UNIX / Linux commands Archive of shell script examples and shell script related articles Bash FAQ wiki Bash hackers wiki