One Pager Cheat Sheet

• We will learn about Linux OS and its architecture, and important concepts to understand about it.
• Linux is an open-source, free, and multi-user operating system that provides enhanced security and authentication features, tends to be made up of various distributions based on the kernel, and is used by multiple users at once.
• The Linux OS is composed of several components such as Kernel, Shell, Hardware, and System Utilities and Applications, which interact with each other to keep the system running.
• The kernel is the core of the Linux architecture responsible for executing commands from the shell, peripheral devices, and system utilities to control memory, hardware, and applications.
• In Linux systems, aprocesscan be "Ready", "Blocked" or "Running" and each is given an uniqueprocess ID(orPID) with a separateaddress spaceto run in.
• The process can be in any one of the three states - Ready, Blocked, or Running - depending on if it is waiting for an I/O operation to complete.
• Linux has a file hierarchy structure, including a root directory, home directory, bin directory, lib directory, and user directory, for organizing system programs, utilities, libraries, and user-specific files and configurations.
• No /usr directory is not the same as /home directory; the /home directory is user-specific for files and configurations, while /usr has user-specific binaries and data for applications installed by the user.
• The system root directory, indicated by a forward slash (/), is the parent directory of all other directories and serves as the root from which all other files and directories stem.
• Knowing Read, Write, and Execute permissions help define data access control for different users in Linux and can be checked using ls -l on the bash terminal.