BASH Programming Training Course

The simplest script

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

Calling the script

External and built-in commands

Some special characters

• Comment (#)
• End of Line (;)
• An empty statement (:)
• Redirection of input output (>, <, >>)
• Redirecting output
• Redirection of input
• Stream (|)
• Start the process in the background (&)

Variables and Parameters

• Unsetting variables (unset)
• Variable with a null value
• Save the result to a variable (backquotes ``)
• Parameter expansion ($ 0, $ #, $ 1, $ 2, $ 3 ...)
• Manual shift
• Quoting.
• Escape character (\)

Regular Expressions

Conditional statements

• The if / then
• The if / then / else
• Nesting if statements
• The if / elif
• case statement
• Operators
• Operators and, or (&&, | |)
• test command

Completing script

The exit statement

Use the status of completion of the program in a script ($?)

Tests and Operators

• Text file operators
• Testing the file type
• Test file attributes

Comparison operators

• Comparing arithmetic using the if command
• Integer comparison operators
• Comparing strings
• Comparing complex conditions (and, or)
• Nesting comparison operators
• The assignment operator
• Arithmetic operators
• Bitwise operators (operations on bits)
• Logical operators
• Numeric constants

Loops

• The for / in loop
• The seq command
• The while loop
• The until loop
• Controlling the loop (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 selection

Functions

Sleep command

What if the script doesn't work? (debugging)