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 statements (:)
• Input/output redirection (>, <, >>)
• Output redirection
• Input redirection
• Piping streams (|)
• Running processes in the background (&)

Variables and Parameters

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

Regular Expressions

Conditional logic

• If / then structures
• If / then / else structures
• Nested if statements
• If / elif structures
• Case statements
• Comparison operators
• Logical and/or operators (&&, | |)
• The test command

Script completion

The exit statement

Leveraging program completion status within a script ($?)

Testing and Operators

• Text file operators
• Determining file types
• Checking file attributes

Comparison Operators

• Arithmetic comparisons using the if command
• Integer comparison operators
• String comparisons
• Complex logic (and, or)
• Nesting comparison operators
• Assignment operators
• Arithmetic operators
• Bitwise operators
• Logical operators
• Numeric constants

Loops

• For / in loops
• The seq command
• While loops
• Until loops
• Loop control (break, continue)

Text Processing

• head and tail commands
• Sort, Uniq, Expand, and Unexpand
• Cut, Paste, Join, Wc, and Tr

Text searching (grep)

Stream editing (sed)

Interactive programs

• The Read command
• User selection

Advanced features

The Sleep command

Troubleshooting non-functional scripts (debugging)