Linux Bash Shell Programming

Course Contents - DAY 1Course Introduction

• Administration and Course Materials
• Course Structure and Agenda
• Delegate and Trainer Introductions

• Basic UNIX commands
• Filename generation characters
• Redirection and pipes

• What is a shell script?
• Development guidelines
• Creating and editing shell scripts
• Naming and storing shell scripts
• Executing shell scripts
• Exercise: Create and run a simple shellscript

• Environment variables
• Local variables
• Assigning values to variables
• Accessing variable values
• Using quotes
• Delimiting variable names
• echo control sequences
• Exercises: Use variables in shellscripts

• Using the expr command
• Using the (( )) notation
• Exercises: Use integer arithmetic in shellscripts

• The read command
• Command line arguments and related variables
• Exercise: Writing an interactive shell script

• The if-then-elif-else statement
• String tests
• Integer tests
• Filename tests
• Other test notations
• Default and substitute variables
• Exit status codes
• Counting characters
• Testing for numeric input
• Exercise: Add validation to previous scripts

• The while loop
• The until loop
• The while true and until false loops
• The for loop
• Loop control commands
• Exercises: Enhance the previously written scripts with loop constructs

• The case statement
• Patterns and actions
• Menu driven applications
• Exercise: Develop and write a menu system

• What is a function?
• Function syntax
• Exercises: Create and use functions

• Interrupt signals
• The trap command
• Abnormal termination of scripts
• Exercise: Adding traps to the menu script

• The exec command
• The includes notation
• Arrays
• Here Documents
• Exercise: Enhance scripts

• The tar command
• Compression utilities gzip, bzip2, zip and compress
• Exercise: Backing up and restoring files using tar
• Exercises: Compressing files

• Scheduling jobs with the cron command
• Scheduling jobs with the at command
• Exercises: Running background jobs

• Compare two files with the cmp command
• Compare two files with the comm command
• Compare two files with the diff and sdiff commands
• Compare large files with the bdiff command
• Exercises: Identifying file differences

• The split and csplit commands
• Exercises: Splitting files

• od - octal dump
• Use cat to display non-printing characters
• The expand and unexpand commands to convert between tab and space characters
• The tr command for character translation
• Exercises: Translating characters with tr

• Standard regular expressions
• Extended regular expressions

• sed command line syntax
• sed command processing
• Pattern space
• sed addresses
• sed commands
• Hold and get functions
• Advanced flow control
• Exercises: Text processing with sed

• Introduction and command line syntax
• The awk program structure
• Operators
• Simple patterns
• Extended patterns
• Special patterns (BEGIN and END)
• Program variables: Built-in variables, User defined variables, Arrays
• Mathematical operators
• Displaying output with print and printf
• Exercises: Create awk scripts to extract selected data from a file and generate reports

• Program control structures
• The if construct
• The while and do ... while constructs
• The basic for construct
• Associative array handling
• Functions: Mathematical and string functions, The system function, The getline function, User defined functions
• Exercises: Create an awk script using an program control structures and arrays

• Responding to Syntax errors
• Responding to Logical errors

• bc (calculator)
• fuser (testing for files in use)
• getops (checking options passed to shell scripts)
• printf (formatting screen output)
• logger (script logging)
• xargs (generating arguments for a command)
• eval (re-evaluating variables)
• Exercises: Using tools within a shell script