History

Unix was first released in 11/3/1971.

What is Unix

Stands for UnipleXed Information Computing System.

• Unix is an operating system.

All MacOS derivatives are Unix certified.

• Compliance required to use the UNIX trademark.

What is a Shell

Shell is a macro processor that executes commands.

alias configuration

alias is a named function used as a shortcut for a command.

# clearing the alias
alias ll='ls -la'

# when command has a quote, prefer function over `alias`
somefn() {
  echo "Hello, World!"
}

History

Linux was released 9/17/1991.

Linux is Unix-like, but not Unix.

Linux is open-source and free, while Unix is proprietary and requires a license.