Chapter 3: Linux Basic Commands
3.10 Text editors: nano and vim
Friends, there is no Notepad on a server – config files have to be edited in nano or vim. Start with nano, but learn the vim basics too, because vim is available almost everywhere.
मित्रांनो, सर्व्हरवर Notepad नसतो – कॉन्फिग फाइल्स nano किंवा vim मध्येच एडिट कराव्या लागतात. Nano ने सुरुवात करा, पण vim चे बेसिक सुद्धा शिका, कारण vim जवळजवळ सगळीकडे असतो.
दोस्तों, सर्वर पर Notepad नहीं होता – कॉन्फ़िग फ़ाइलें nano या vim में ही एडिट करनी पड़ती हैं. Nano से शुरुआत करो, लेकिन vim के बेसिक भी सीखो, क्योंकि vim लगभग हर जगह होता है.
nano — easiest for beginners
sudo nano /etc/nginx/nginx.conf
Shortcuts are shown at the bottom (^ means Ctrl): Ctrl+O then Enter = save, Ctrl+X = exit, Ctrl+W = search, Ctrl+K = cut line, Ctrl+U = paste.
vim — available everywhere
Vim has modes: Normal (for commands, the default), Insert (for typing) and Command-line (after :).
| Keys | Action |
|---|---|
i |
Enter insert mode (start typing) |
Esc |
Back to normal mode |
:w |
Save |
:q |
Quit (:q! quit without saving) |
:wq or ZZ |
Save and quit |
dd / yy / p |
Delete (cut) line / copy line / paste |
u / Ctrl+R |
Undo / redo |
/text then n |
Search forward, next match |
:set number |
Show line numbers |
gg / G |
Go to first / last line |
:%s/old/new/g |
Replace all |
Stuck in vim?
Press Esc two times, then type :q! and press Enter. You are out without saving.
Ravindra Bagale's Tip
When stuck in Vim, many students close the terminal, and then .swp warnings appear when they open the file. Don't panic: press Esc twice, then :q! and Enter. And if you type :wq in insert mode, it gets written into the file itself – don't forget to press Esc first.
Ravindra Bagale's Tip – मराठी
Vim मध्ये अडकल्यावर बरेच students terminal बंद करतात, आणि मग file उघडताना .swp warnings येतात. घाबरू नका: Esc दोन वेळा, मग :q! आणि Enter. आणि insert mode मध्ये :wq type केलं तर ते file मध्येच लिहिलं जातं – आधी Esc दाबायला विसरू नका.
Ravindra Bagale's Tip – हिंदी
Vim में अटकने पर बहुत से students terminal बंद कर देते हैं, और फिर file खोलते समय .swp warnings आती हैं. घबराओ मत: Esc दो बार, फिर :q! और Enter. और insert mode में :wq type किया तो वो file में ही लिख जाता है – पहले Esc दबाना मत भूलना.
Lab
Chala, nano ~/labs/mauli/notes.txt madhe the Amul-style dairy che teen products (pedhe, shrikhand, lassi) liha, Ctrl+O ne save kara aani Ctrl+X ne baher ya. Mag tich file vim madhe ughda, :set number kara, ek line dd ne delete kara aani :wq ne save kara.
Extended teaching notes
Why this lesson matters
Cloud security is mostly IAM, network exposure, logging and secure defaults. The shared responsibility model means the provider patches the metal; you patch what you configure.
- No public databases or public admin panels.
- Roles / OIDC instead of long-lived access keys.
- CloudTrail / Activity Logs / Audit Logs on and retained.
- S3/Blob/GCS: Block Public Access; encrypt; least privilege.
Mini case study
Suppose we are on a purple-team exercise for an Indian mid-size company (sample data). Red notes a technique from this lesson against a lab clone. Blue must show the control that stops it, the log that would have fired, and the ticket that hardens production. That is the standard this course trains you for.
Defender's worksheet (do this today)
- Write the lesson title, date and the exact lab target you are allowed to use.
- List three owned systems (VMs, apps, or cloud accounts) where this lesson applies.
- Run one safe check from the lesson on a lab system only. Paste the command and output.
- Write a two-sentence fix you would give a teammate.
- Name one related public advisory (CERT-In, CISA, NVD, or a vendor bulletin) with its date.
Indian workplace (sample data)
Suppose we are a junior analyst at Infosys, TCS, Wipro or a fintech SOC in Bengaluru/Pune. Turn this lesson into one checklist item with an owner, a due date and a place to store evidence (ticket + screenshot).
Global practice
Compare your notes with OWASP, CIS Benchmarks, NIST CSF/IR guidance or a cloud Well-Architected security question. Write five lines on what overlaps.
Everyday analogy
Explain the risk and the fix to a family member without jargon. If they can repeat the warning, you understand it well enough to teach juniors.
Key terms
- Control: a safeguard (patch, config, process, detection).
- Finding: a weakness backed by evidence.
- Remediation: the fix plus how you verified it.
- Scope: systems you have written permission to touch.
- Least privilege: only the access the task needs.
- Defence in depth: several layers so one failure does not end the story.
Common mistakes
- Skipping written permission "just for a quick scan".
- Practising on hostel, office or public targets without authorisation.
- Collecting tool output without writing the fix.
- Copying attack steps onto production to "verify". Defenders verify with versions, configs and patches.
- Publishing screenshots that contain secrets, cookies or internal hostnames.
Recap
- Evidence, fix, owner, date.
- Own lab only.
- Fix > spectacle.