5.1 The Linux File-System Hierarchy
Windows madhe C: drive asto, Linux madhe sagla ek / (root) khali asto. Kontya folder madhe kay aahe he mahit asla ki troubleshooting aani investigation – donhi fast hotat.
/ root of everything
├── bin, sbin essential commands (now links to /usr/bin, /usr/sbin)
├── boot kernel and boot loader
├── dev device files (/dev/nvme0n1, /dev/xvda)
├── etc configuration files (nginx, ssh, fstab, passwd)
├── home users' home folders (/home/ec2-user, /home/ubuntu)
├── root home of the root user
├── opt optional / third-party software
├── tmp temporary files (cleared on reboot)
├── usr programs, libraries, docs (/usr/share/nginx/html)
├── var variable data: logs (/var/log), web (/var/www), databases (/var/lib/mysql)
├── proc, sys virtual files with kernel & hardware info
└── mnt, media mount points for extra disks
Everything is a file
In Linux, disks (/dev/nvme1n1), processes (/proc/1234) and even hardware info are represented as files. Paths are case-sensitive: Index.html and index.html are different files.
| Security-relevant path | Why an attacker or defender looks here |
|---|---|
/etc/passwd, /etc/shadow |
User accounts and password hashes |
/etc/ssh/sshd_config |
SSH settings – root login, password login |
/var/log/ |
Evidence: auth logs, web logs, system logs |
/tmp, /dev/shm |
World-writable – attackers often drop tools here |
/home/*/.ssh/ |
Private keys and authorized_keys |
/var/www/ |
Web application code and config files with passwords |
Why this matters for security
During privilege escalation (विशेषाधिकार वाढवणे) an attacker searches exactly these paths for passwords, keys and mistakes. During incident response, a defender checks the same paths for evidence. Knowing the map is half the job for both sides.
Ravindra Bagale's Tip
Many students confuse /root with / (the root directory). / is the starting folder of everything; /root is the root user's home folder. If you use the word "root" in an interview, make clear which meaning you intend.
Ravindra Bagale's Tip – मराठी
बरेच students /root आणि / (root directory) मध्ये गोंधळ करतात. / म्हणजे सगळ्याचा सुरुवातीचा folder; /root म्हणजे root user चा home folder. Interview मध्ये "root" शब्द वापरला तर कोणत्या अर्थाने ते स्पष्ट सांगा.
Ravindra Bagale's Tip – हिंदी
बहुत से students /root और / (root directory) में गड़बड़ करते हैं. / यानी सबका शुरुआती folder; /root यानी root user का home folder. Interview में "root" शब्द इस्तेमाल करो तो साफ़ बताओ कि किस मतलब में.
Practice task
Run ls /, ls /etc | head, ls -la ~ and sudo ls /var/log. Write one line about what each folder contains.