File System

• Home directory is where each users personal files gets stored. The home directory is similar to the Users directory in Windows.
• root directory is the root of the entire filesystem. Think C: for Windows. In Windows if you connected an additional hard drive you would see a D: drive, an E: drive, etc. Each of these letters represents the "root" of that additional hard drive in Windows. In Linux we don't have drive letters, we only have one root and in the root folder you will see folders like "mnt" and "media". These are folders where our additional hard drives, cd drives, or flash drives get mounted. Let's go over the directory structure of root now:
  • bin: The bin folder contains most of our basic executable programs or "binaries", which is where bin gets its name, lives. If you look in the bin directory you will see programs like LS or CP live there.
  • boot: This folder contains all of the files necessary to boot your system. This folder is normally only used by your boot manager ie: grub
  • dev: This is where all of your devices live. Linux follows the Unix mentality that everything about your computer is a file, so in this dev directory you will see file representation of all of your computer hardware. An example of this can be seen when we look in the dev directory you may see files called sda, sda2, sdb, etc. All of the "sd" files are disk drives, whether they be internal or external, and the third letter represents the number of the device starting with "a" (your boot drive). The numbers if present for that drive represent the individual partitions of that drive. If you are new to the concept of drive partitioning look at my guide: Partitioning.
  • etc: This directory contains configuration files for system wide programs. The name "etc" is shorthand for the word etcetera and in the early days of Unix etc was used to store the extra files that didn't below in bin, dev, or lib. Over the years the directory has changed its purpose to a place to house configuration files but hasn't changed its name and therefore is still called etc. For instance if we look in the X11 directory of etc: ls /etc/X11/ we see the configuration files for our X server.
  • lib: Some distos may have multiple "lib" directories for instance on my system I have both a lib directory and a lib64 directory. Either way these folders just contain binaries for our applications.
  • media: Most distros will handle mounting additional drives automatically and will more than likely mount them in the "media" folder.
  • opt: The opt folder stands for optional and typically just contains drivers from vendors.
  • proc: The proc directory is where you will normally find a bunch of pseudo files that contain information about processes running on your system. If you look in proc you will see multiple directories that are just a string of numbers. These numbers correlate to the PIDs, or process IDs, of your running programs. If you use a program like htop to see your PIDs you will see that each one has a directory in proc.
  • root: The root directory is the home directory of the root user. On most distros the root directory is generally empty.
  • run: The run directory is very different than most of the other directories. The run directory runs a tmp filesystem and everything inside of the run folder is loaded into ram and everything in the run directory gets deleted when the system gets restarted. These files are generally just files that the system needs to boot.
  • sbin: This directory contains the system binaries for our system. These are programs that only an administrator would use so in order to access or use any of the programs in this directory you need to be the root user or using sudo.
  • srv: This directory contains files pertaining to services running on your machine, say ftp or http. In most cases if you are using your machine as a daily driver you probably won't be running services like this so the srv directory will be empty.
  • sys: The sys directory, short for system, gives us access to files let us interact with the system kernel. Messing with your kernel isn't something you would normally do so you probably won't do anything in this directory normally.
  • tmp: The tmp directory, short for temporary, is a place for temporary files to be stored that will be wiped when the system reboots. This directory normally contains temporary files for programs to use during their running session. For instance if you are working on a document that you haven't saved yet a copy of that file will be saved here so if your document editor crashes your work will still be stored in tmp as long as you don't reboot.
  • usr: The usr directory, short for user, is a place for programs that can be used by the user. This isn't to be confused with the bin directory as bin contains programs that anyone on the system can use, whereas usr contains programs that can only be accessed by the current user. If you ever install an application and it has an option to install for all users it will install to each users usr directory, whereas if you install for the current user only it will install in your users directory in usr.
  • var: The var directory, short for variable, contains files and directories which will grow in size as you are running your system. This includes things like crash data which will get appended too whenever something crashes on your system.