Unix/Linux Shell Scripting

Course details

The course needs prior knowledge of basic Linux / Unix commands and introduces how to script the shell from very basics to advanced techniques. Many useful scripts, required on job everyday are written in the course by participants, for example Scripts to FTP, check disk usage, monitor computer resources etc.

Who Should Take This Course:

Shell Scripting allows to automate everyday tasks very efficiently. All users working on Unix / Linux / Redhat / Suse / Solaris / AIX / HPUX platforms must learn shell scripting. It is a must for system administrators on the above platforms.

Course Content:

Introduction

• Introduction to Shell scripts.
• Considerations to write bash shell scripts.
• Exercises on shell scripts

Shell Basics

• Introduction to Shell
• Shell Command Syntax
• Special Characters
• Pattern Matching
• Complex Pattern Combinations
• Tilde & Other Expansions
• Exercises

Writing Scripts

• Shell Programming Language
• Reserved Words
• How to Write and Run Scripts
• Debugging Shell Scripts
• Data Types in Shell Scripts
• Using Variables & Constants
• Special Predefined Variables
• Printing to the Screen for various scenarios
• Accepting User Input
• Formatting Display & User Input
• Arithmetic & Logical Operators
• Quoting
• Exercises

Programming Logic

• Conditional Expressions
• Testing Operators
• Testing Strings
• Testing Options
• Numeric Conditions
• Testing Completion Status
• Loops: if, while and until
• The case Statement
• The for Loop
• When to Use Different Constructs
• Writing Scripts to display menus
• Exercises

String Manipulation

• String Comparison
• Concatenation
• Substring Manipulations
• Wildcards and Pattern Matching
• Exercises

Command Line Processing

• Getting Data Into Scripts
• Manipulating Positional Parameters
• Analyzing Switches with getopts
• Options

Overview of File Manipulation Utilities

• Unix and Linux Utilities to Manipulate Files
• Editing a File from a Script
• Regular Expressions
• Transforming File Contents
• Extracting Text Strings

Functions

• Writing Functions
• Returning Value from Functions
• Returning String Output
• Local and Global Variables
• Defining Functions
• Writing a function library to use in many scripts

Advanced I/O with Streams

• Redirection Operators
• Manipulating Data Streams
• here Documents
• Using here doc to comment scripts
• Using here doc to write html files
• Using here doc to display segments of data to user and gather inputs

Script Execution in Cron

• Scheduling Execution Of Shell Scripts
• Manage input and output from scripts in cron

Advanced Techniques in ShellScripts

• Using environment variables inside shell scripts
• Statement / Code blocks
• Writing multiple files from a single script
• Capturing output from various sections of the script into multiple files
• Calling shell scripts from within shell scripts and passing return status and data between them Processing log files from shell scripts
• Writing lock files to avoid resource contention and deadlocks

Considerations For Writing Good Shell Script

• Writing clean syntax
• Standard style of documenting shell scripts
• Maintaining script version history
• Auto-indenting shell scripts
• Simplifying your scripts

Security

• Security considerations while writing shell scripts
• Script Process Ownership
• suid and sgid
• Other Security Features

Performance and Porting Issues

• Improving the Performance of Scripts
• Portability Issues

Q & A Session