File system is used to handle the data management of the storage.

Linux vs Windows File System

• Linux File System has a hierarchical tree structure and uses Ext4, ZFS, JFS, btrfs etc.
• It has only 1 root folder.
• Existence of swap partitions, you never run out of memory in Linux (like in windows).

Windows in comparison

• Windows uses FAT (File Allocation Table) and NTFS (New Technology File system).
• It has multiple root folders.

Does Linux use NTFS?

NTFS file-storing system is standard on Windows machines, but Linux systems also use it to organize data.

EVERYTHING in Linux is a FILE

Everything in the system is represented by a file descriptor, Text documents, pictures etc, Commands like pwd, ls etc, Devices like printer, keyboard, USB, even directories. Linux makes no difference between a file and a directory, since a directory is just a file containing names of other files.

Unlike Windows or other operating-systems, Here in Linux root(/) is the base and all other files are the children. Let’s discuss each of them in detail.

1. /

Root

• In the Linux file system, everything comes under the root directory.
• The root user's home directory is at /root.

2./home

Contains home directories of all the non-root users.

• Possible to have multiple user accounts on 1 computer.
• Each user has its own space.
• Each user can have own configurations.

3. /bin

Binaries; executables for most essential user commands.

• A binary file is a computer- readable format.
• These are the commands which are available to all the users. Commands like cd, mv, nano etc are loading from here.

4. /sbin

System binaries; essential system binaries programs that admin would use.

• There are some binary files which are hidden from normal users.
• These commands are available to root users.
• System binary executable commands such as ifconfig, fdisk can be accessed from here.

5. /lib

Library; essential shared libraries that executables from /bin or /sbin use.

• Contains shared libraries which are often used by the '/bin' and '/sbin' directories.
• It also contains kernel module.
• These filenames are identable as ld or lib.so.*. For example, ld-linux.so.2 and libfuse.so.2.8.6.

6. /usr

User; used for user home directories.

• /usr/local

  • Programs that you install on the computer, third-party applications like docker, minikube, java etc.
  • Programs installed here will be available for all users on the computer.
  • Inside /usr/local: App installation will be split again into different folders.

Do you what's the history behind two /bin files?

Because of storage limitations, it was split to root binary folders and user binary folders.

7. /opt

Optional; third-party program you install.

So what's the difference between /usr/local and /opt?.

• Third-party apps whose components aren't split between bin and lib files use /opt files.
• Programs, which split its components uses /usr/local.
• /opt is used for those program which do not split it components. Example: IDE, Web Browser.

8. /etc

Et cetera

• Contains system-wide configuration files.
• Here you’ll find configuration files of most of the applications and user configuration files.
• For example, Linux stores the password of each user in this directory.

9. /tmp

Temporary

• This is a volatile directory.
• Applications use this directory to store the temporary files until the system reboots.
• If any application crashes you can recover the files here.

10. /boot

Booting; contains files required for booting.

• Files that are required to boot into your systems such as grub and EFI.
• Messing with these files can make your system not boot.

11. /dev

Devices; location of device files like webcam, keyboard, hard drive etc.

• Apps and Drivers will access this, NOT the user.
• Files that the system needs to interact with the device.

12. /var

Variable; contains files to which the system writes data during the course of its operation.

• /var/log : Contains log files
• /var/cache: Contains cached data from application programs

13. /media

• Contains subdirectories, where removable media devices inserted into the computer are mounted.
• E.g. when you insert a CD. A directory will automatically be created and you can access the contents of the CD inside the directory.

14. /mnt

• Temporary mount points.
• Historically, system administrators mounted temporary file systems here.

Hidden Files

• Hidden files are primarily used to help prevent important data from being accidentally deleted.
• Automatically generated by programs or OS.
• File name starts with a dot.