Linux File Management

Overview

Time: 10 min

Learn the file oragnisation in a Linux OS.

Understand the difference between Unix and Linux.

Explanation

Difference between Unix and Linux:

Unix vs Linux Comparison

Feature

Unix

Linux

Proprietary or Free?

Proprietary (mostly)

Free and open source

Developed When?

1970s

1991

Developed By

AT&T Bell Labs

Linus Torvalds + community

Variants

AIX, HP-UX, Solaris, etc.

Ubuntu, Fedora, Debian, etc.

Certification

Unix-certified by The Open Group

Not Unix-certified

Linux File System

/
├── bin
├── boot
├── dev
├── etc
├── home
│   ├── alice
│   └── bob
├── lib
├── media
├── mnt
├── opt
├── proc
├── root
├── run
├── sbin
├── tmp
├── usr
│   ├── bin
│   ├── lib
│   └── share
└── var
    └── log

The Linux filesystem is organized as a hierarchical directory tree. Below is a breakdown of the top-level directories and their purposes according to the Filesystem Hierarchy Standard (FHS).

Root Directory

/: The root of the filesystem. All other directories stem from here.

System and Boot Directories

/bin: Essential user binaries needed for basic system functionality, such as ls, cp, and mv.
/sbin: Essential system binaries, typically used for system administration, such as fsck and reboot.
/boot: Contains files needed to boot the system, including the Linux kernel and bootloader configurations.
/lib and /lib64: Shared libraries required by binaries in /bin and /sbin. /lib64 holds 64-bit libraries.

User and Software Directories

/usr

Secondary hierarchy for read-only user data and installed software. Contains:

/usr/bin: Non-essential user binaries.
/usr/lib: Libraries for binaries in /usr/bin.
/usr/share: Architecture-independent shared data.

/opt

Optional software packages from third-party vendors.

/home

Home directories for all users (e.g., /home/alice, /home/bob).

/root

Home directory of the root (superuser).

Configuration and Temporary Directories

/etc: Host-specific configuration files.
/tmp: Temporary files used by applications, typically cleared on reboot.
/var: Variable data files, such as logs, mail, and spool directories.

Devices and Mount Points

/dev: Contains device files (e.g., /dev/sda, /dev/null), which represent hardware devices.
/proc: Virtual filesystem providing process and kernel information as files (e.g., /proc/cpuinfo).
/sys: Virtual filesystem for exposing information about hardware devices and associated kernel modules.
/run: Stores volatile runtime data like PID files and socket information.
/mnt: Used for temporarily mounting filesystems, often by system administrators.
/media: Mount point for removable media such as USB drives and CD-ROMs.

Extra HPC directories:

HPC Directory Explanations
Directory	Explanation
`apps/`	Pre-installed or centrally maintained software applications available to all users (e.g. compilers, MPI, MATLAB, etc.). Often used with modules like `module load`.
`g/`	Likely a group-shared storage area. Often used in universities or research orgs for shared group project files.
`scratch/`	High-performance temporary workspace for large files or experiments. Usually purged periodically.

Key Points

Linux follows a hierarchical directory structure, starting from the root directory /.

Key directories include /bin, /sbin, /usr, /etc, /home, and /var.

Key HPC directories include apps/, g/, and scratch/.