BASH Programming Training Course

The simplest script

Selecting the shell (magic number #!, Sha-bang)

Invoking the script

External and built-in commands

Notable special characters

• Comments (#)
• End of Line (;)
• Empty statement (:)
• Input/Output redirection (>, <, >>)
• Redirecting output
• Redirection of input
• Piping streams (|)
• Executing processes in the background (&)

Variables and Parameters

• Removing variables (unset)
• Variables with null values
• Storing results in variables (backquotes ``)
• Accessing parameters ($ 0, $ #, $ 1, $ 2, $ 3 ...)
• Manual shifting
• Quoting mechanisms.
• Escape character (\)

Regular Expressions

Conditional Logic

• The if\/then structure
• The if\/then\/else structure
• Nested if statements
• The if\/elif structure
• The case statement
• Comparison operators
• Logical operators and/or (&&, | |)
• The test command

Script Termination

The exit statement

Utilizing the program's completion status within a script ($?)

Tests and Operators

• Text file operators
• Verifying file types
• Testing file attributes

Comparison Operators

• Arithmetic comparisons using the if command
• Integer comparison operators
• String comparisons
• Complex comparisons (and, or)
• Nesting comparison operators
• The assignment operator
• Arithmetic operators
• Bitwise operators for bit operations
• Logical operators
• Numeric constants

Loops

• The for\/in loop
• The seq command
• The while loop
• The until loop
• Loop control (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

• The Read command
• User selection

Additional Features

The Sleep command

Troubleshooting non-functional scripts (debugging)