BASH Programming Training Course

The simplest script

Choosing the shell (magic number #!, Shebang)

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

• Variable destruction (unset)
• Variable with a null value
• Save the result to a variable (backquotes ``)
• Parameter requests ($ 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
• Logical operators and, or (&&, | |)
• test command

Completing the script

The exit statement

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

Tests and Operators

• Text file operators
• Tests for file type
• Test file attributes

Comparison operators

• Comparing arithmetic using the if command
• Integer comparison operators
• Comparing strings
• Complex comparisons (and, or)
• Nesting comparison operators
• The assignment operator
• Arithmetic operators
• Bitwise operators
• Logical operators
• Numeric constants

Loops

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

Functions

sleep command

If the script does not work? (debugging)