BASH Programming Training Course

The Simplest Script

Selecting the Shell (Magic Number #!, Shebang)

Invoking the Script

External and Built-in Commands

Special Characters

• Comments (#)
• End of Line (;)
• Empty Statement (:)
• Input/Output Redirection (>, <, >>)
• Redirecting Output
• Redirecting Input
• Streams (|)
• Starting Processes in the Background (&)

Variables and Parameters

• Variable Destruction (unset)
• Variables with Null Values
• Storing Results in Variables (Backquotes ``)
• Parameter Queries ($0, $#,$1,$2,$3...)
• Manual Shift
• Quoting
• Escape Character (\)

Regular Expressions

Conditional Statements

• if/then
• if/then/else
• Nesting If Statements
• if/elif
• Case Statement
• Operators
• Logical Operators (&&, ||)
• Test Command

Completing the Script

The Exit Statement

Utilizing the Program Completion Status in a Script ($?)

Tests and Operators

• File Operators
• File Type Tests
• File Attribute Tests

Comparison Operators

• Arithmetic Comparison Using the If Command
• Integer Comparison Operators
• String Comparison
• Complex Comparisons (and, or)
• Nesting Comparison Operators
• Assignment Operator
• Arithmetic Operators
• Bitwise Operators
• Logical Operators
• Numeric Constants

Loops

• For/In Loop
• The Seq Command
• While Loop
• Until Loop
• Controlling Loops (break, continue)

Text Processing

• Head and Tail Commands
• Sort, Uniq, Expand, Unexpand
• Cut, Paste, Join, Wc, Tr

Text Search (grep)

Stream Editor (sed)

Interactive Programs

• Read Command
• User Select

Features

Sleep Command

What If the Script Does Not Work? (Debugging)