`Unix`

Unix was first released in 11/3/1971.

Stands for UnipleXed Information Computing System.

Unix is an operating system.

All MacOS derivatives are Unix certified.

shares a lot of the same ideas and software that a GNU/Linux system uses.

Compliance required to use the UNIX trademark.

GNU/Linux is a free alternative to UNIX.

Since the 70s, UNIX became an umbrella term that groups many operating systems.

Common Filesystem

/bin contains the main system commands
/etc contains the system configuration
/dev contains the system devices
/usr contains the user files
/tmp contains the temporary files

`Shell`

Shell is a macro processor that executes commands.

Command interpreter that exposes an interface to work with underlying operating system.

`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!"
}

Linux History

The Linux “core” (called kernel) was born in 9/17/1991 in Finland, and it went a really long way from its humble beginnings.

It went on to be the kernel of the GNU Operating System, creating the duo GNU/Linux.

Linux is Unix-like, but not Unix.

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

Linux has many different versions called distributions.

distros are made by a company or organization and packages the Linux core with additional programs and tooling.

Linux Standard Filesystem

/bin the main system commands
/boot the files used to boot the machine (not existing on macOS)
/dev system devices
/etc system configuration files
/etc/opt user programs configuration files
/home the home directories of users (/Users in macOS)
/lib the system libraries (not existing on macOS)
/mnt mounted filesystems
/opt user programs
/proc user by kernel and processes (not existing on macOS)
/root the home folder of the root user (not existing on macOS)
/run (not existing on macOS)
/sbin system binaries user for booting the system
/tmp temporary files
/usr holds user software, libraries and tools
/usr/bin user binaries
/usr/include user header files
/usr/lib user libraries
/usr/local used by user software to store installations, like Homebrew on macOS
/usr/sbin system binaries
/usr/share contains architecture-independent data. It can hold a lot of miscellaneous stuff including documentation and man pages
/usr/src contains the source code of installed packages (not existing in macOS)
/var contains temporary files, logs and more

Unix