Chapter 4: Linux Advanced Commands
4.12 Monitoring: top and htop
In short: top is always available. htop is friendlier (colour, mouse, F-keys): sudo apt install -y htop (Ubuntu), sudo yum install -y htop (AL2023; on CentOS Stream enable EPEL first).
Friends, when a server becomes slow, the first question is – who is eating the CPU and how much RAM is left? top is the live dashboard, and htop is its colourful, easier brother.
मित्रांनो, सर्व्हर स्लो झाला की पहिला प्रश्न – CPU कोण खातो आणि RAM किती उरली? top हा लाइव्ह डॅशबोर्ड आहे, आणि htop त्याचा रंगीत, सोपा भाऊ.
दोस्तों, सर्वर स्लो हुआ तो पहला सवाल – CPU कौन खा रहा है और RAM कितनी बची है? top लाइव डैशबोर्ड है, और htop उसका रंगीन, आसान भाई.
top is always available. htop is friendlier (colour, mouse, F-keys): sudo apt install -y htop (Ubuntu), sudo yum install -y htop (AL2023; on CentOS Stream enable EPEL first).
| In top | Action |
|---|---|
P / M |
Sort by CPU / memory |
k |
Kill a process (enter PID) |
1 |
Show each CPU core |
q |
Quit |
Key numbers: load average (should be below the number of vCPUs), %CPU, %MEM, RES memory, and wa (I/O wait — high means disk is slow).
Ravindra Bagale's Tip
Many students panic when they see a load average of 1.5. Remember: if the load average is below the number of vCPUs, it's fine – a t3.micro has 2 vCPUs (Chapter 5). And if wa is high, the problem is not the CPU but a slow disk.
Ravindra Bagale's Tip – मराठी
बरेच students load average 1.5 बघून घाबरतात. लक्षात ठेवा: load average vCPUs च्या नंबरपेक्षा कमी असेल तर ठीक आहे – t3.micro ला 2 vCPU आहेत (Chapter 5). आणि wa जास्त असेल तर CPU नाही, disk slow आहे.
Ravindra Bagale's Tip – हिंदी
बहुत से students load average 1.5 देखकर घबरा जाते हैं. याद रखो: load average vCPUs के नंबर से कम है तो ठीक है – t3.micro में 2 vCPU हैं (Chapter 5). और wa ज़्यादा है तो CPU नहीं, disk slow है.
Lab
Chala, ek terminal madhe top ughda aani dusrya terminal madhe yes > /dev/null & chalva – top madhe P dabun CPU khanari process bagha. Mag pkill yes ne ti band kara aani load average halu halu kami hota ka te bagha.
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.