BASH Programming Training Course

The simplest script

Selecting the shell (magic number #!, Shebang)

Executing the script

External and built-in commands

Special characters

• Comments (#)
• End of line (;)
• Empty statement (:)
• Input/output redirection (>, <, >>)
• Output redirection
• Input redirection
• Pipes (|)
• Running processes in the background (&)

Variables and Parameters

• Deleting variables (unset)
• Variables with null values
• Storing results in variables (backticks ``)
• Parameter expansion ($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: AND, OR (&&, ||)
• test command

Script completion

The exit statement

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

Tests and Operators

• File text 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
• The assignment operator
• Arithmetic operators
• Bitwise operators
• Logical operators
• Numeric constants

Loops

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

Text Processing

• head, tail commands
• sort, uniq, expand, unexpand
• cut, paste, join, wc, tr

Text search (grep)

Stream Editor (sed)

Interactive programs

• read command
• select

Utilities

sleep command

Troubleshooting: What if the script fails? (Debugging)