Linux Directories

Cybersecurity Linux Lesson 1.1.1

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/boot (boot)

• The /boot (read as root, boot) directory contains all the files required for the system’s boot process
  • Includes the kernel of the system, RAM images, bootloader configuration files, etc.

    /proc (processes)

• The /proc directory contains information about processes, hardware configuration, and kernel parameters
  • E.g. /proc/in.fo provides information about the system’s CPU

    /sys (system info)

• The /sys directory holds information about the kernel parameters and device attributed
  • E.g. /sys/gpio can manipulate the GPIO pins on embedded systems

    /var (variables)

• The /var directory contains all the files that change while the system is being used
  • Mainly used for storing variables data that is generated by services and applications
  • Logs are stored in /var/log
  • Cached data is stored in /var/cache

    /usr (user’s info)

• The /usr directory contains data and resources about system users
  • /usr/bin contains commands, executables, utilities, and applications
  • /usr/share contains fonts, images, documentations, etc

    /lib (libraries)

• The /lib directory contains libraries for the system typically needed for the early stages of the boot process
  • Occassionally split in /lib32 and /lib 64 for 32-bit and 64-bit libraries, respectively

    /dev (hardware devices)

• The /dev directory contains device files that provide access to hardware devices on the system
  • /dev/sda typically represents the first hard drive (or /dev/sda1 as first partition)
  • /dev/ttyS0 is usually a serial port
  • /dev/null and /dev/zero are used for input/output

    /etc (config files)

• The /etc directory contains configuration files and shell scripts for the system
  • /etc/fstab is the file system table

    /opt (optional software)

• The /opt directory holds optional/add-on software packages
  • Allows for easy management and helps prevent conflicts with system files

    /bin (binaries or commands)

• The /bin directory contains the essential executable files for the system to function
  • Contains the fundamental commands for the system to function including ls, cp, mv, etc.

    /sbin (system binaries or commands)

• The /sbin directory is reserved for system administrators and contained essential system binaries
  • Commands included within this directory are fdisk, reboot, and ifconfig
  • These commands must be run as superuser

    /home (user directory folder)

• The /home directory is where system users home directories are located
  • /home/student would be the home directory for a user, student

    /root (root directory folder)

• The /root directory is the home directory for the superuser/root account
  • Contains config files, scripts, etc.

    /media (removable storage devices)

• The /media directory is used as a mount point for removable media devices such as USB drives, external hard drives, optical discs, etc.

  /mnt (mount point)

• The /mnt directory is a general-purpose mount point used for temporarily mounting filesystems or devices
  • /mnt can be used for any kind of mount operation

    /tmp (temporary files)

• The /tmp directory is a location for storing temporary files and directories
  • May be deleted by the system during reboots or to free up disk space