• Linux directory structure starts from root /

  • Linux Filesystem Hierarchy Standard (FHS) : establishes how data is stored

  • programs are distributed in three-tier structure

    • / is the first tire and can be necessary in single-user
    • /usr contains most multi-user programs
    • distribution /usr/local is used to store software that is not provided by the and has been compiled locally

  • /sbin : contains binaries for sysadmin

    • parted
    • ip

  • /bin : binaries for all users

    • This is an important folder for system rescue; Those that were absolutely needed. This was a previous tactic but still here
    • ls
    • mv
    • mkdir

  • /usr/sbin : binaries for system admin

    • deluser
    • groupadd

  • /usr/share/bin : This is mentioned in other content material, but it is important to note if a particular program has dependent programs or other apps. like Apache

  • /usr/bin : executable files

    • This is for most programs
    • free
    • pstree
    • sudo
    • man

  • /usr/local/sbin : used to sore locally installed programs for sysadmin not managed by sys pkg manager

  • /usr/local/bin : same as sbin but for user programs

    • locally compiled programs that have been manually installed by the user

  • /var/log : where log files are located

    • sometimes programs will have their own directory in this section with their own logs

  • /etc directory or et cetera was created as a catch-all directory to store any files that do not belong in other categories usually config files

    • group - system group database
    • hostname - name of host computer
    • hosts - list of IP addy and their hostname translations
    • passwd - system user database
    • profile - system-wide config file for bash
    • shadow - encrypted file for user passwords

  • bash.bashrc - system wide for interactive bash shells

  • nanorc - sample initialization file for GNU nano

  • resolve.conf - config file for the resolver - provides access to Internet Domain Name System (DNS)

  • sysctl.conf - config file to set system variables for the kernel

  • *.d directories - help to build modular, more robust configurations

  • (.) -files that are hidden start with a period/dot

    • some dotfiles are bash scripts that customize the user’s shell session and are sources as soon as the user logs into the system
      • .bash_history - stores command line history
      • .bash_logout - includes commands to execute when leaving the login shell
      • .bashrc - Bash’s initialization script for non-login shells
      • .profile - Bash’s initialization script for login shells

  • Linux Kernel must be loaded into protected area of memory before any processes can run

    • /sbin/init was always the first process until /lib/systemd/systemd
    • PID1 sets of the chain of processes
    • Linux kernel is in charge of allocating resources to things like keyboard, mouse, disks, memory..etc
    • Kernel resides in /boot
    • grub - configuration directory for the grub2 bootloader