Top 50 Linux commands for DevOps, real-world use

Category	Command	Purpose	Example
File Management	ls	List files and directories	ls -l
File Management	cd	Change directory	cd /var/log
File Management	pwd	Show current directory	pwd
File Management	mkdir	Create directory	mkdir devops
File Management	rmdir	Remove empty directory	rmdir testdir
File Management	rm	Remove files/directories	rm -rf logs/
File Management	cp	Copy files	cp file1.txt file2.txt
File Management	mv	Move/rename files	mv old.txt new.txt
File Management	touch	Create empty file	touch app.log
File Management	find	Search files	find / -name app.log
File Viewing	cat	Display file content	cat file.txt
File Viewing	less	View file page by page	less /var/log/syslog
File Viewing	more	View file content	more file.txt
File Viewing	head	Show first lines	head -10 file.txt
File Viewing	tail	Show last lines	tail -10 file.txt
File Viewing	tail -f	Monitor logs live	tail -f app.log
Text Processing	grep	Search patterns	grep "error" app.log
Text Processing	cut	Extract columns	cut -d":" -f1 /etc/passwd
Text Processing	awk	Process text	awk '{print $1}' file.txt
Text Processing	sed	Edit streams	sed 's/error/warning/g' file.txt
Permissions	chmod	Change permissions	chmod 755 script.sh
Permissions	chown	Change owner	chown user:user file.txt
Permissions	chgrp	Change group	chgrp devops file.txt
Permissions	umask	Default permissions	umask 022
Process	ps	Show processes	ps aux
Process	top	Monitor processes	top
Process	htop	Interactive monitor	htop
Process	kill	Kill process	kill 1234
Process	killall	Kill by name	killall nginx
Process	nice	Set priority	nice -n 10 command
Process	renice	Change priority	renice 5 -p 1234
Networking	ip a	Show IP address	ip a
Networking	ping	Test connectivity	ping google.com
Networking	curl	HTTP requests	curl http://example.com
Networking	wget	Download files	wget http://file.com/app.zip
Networking	netstat	Network connections	netstat -tulnp
Networking	ss	Socket stats	ss -tuln
Networking	scp	Secure copy	scp file.txt user@host:/tmp
Networking	ssh	Remote login	ssh user@192.168.1.10
Networking	traceroute	Trace route	traceroute google.com
Disk Usage	df -h	Disk usage	df -h
Disk Usage	du -sh	Directory size	du -sh /var/log
Disk Usage	lsblk	Block devices	lsblk
Disk Usage	mount	Mount filesystem	mount /dev/sdb1 /mnt
Disk Usage	fdisk	Disk partition	fdisk -l
System	uname -a	System info	uname -a
System	uptime	System uptime	uptime
System	free -m	Memory usage	free -m
System	systemctl	Service management	systemctl status nginx
System	env	Environment variables	env

1. File & Directory Management

ls – list files and directories
cd – change directory
pwd – print working directory
mkdir – create directory
rmdir – remove empty directory
rm – remove files/directories
cp – copy files
mv – move/rename files
touch – create empty file
find – search files/directories

Category	Command	Purpose	Example
File Management	ls	List files and directories	ls -l
File Management	cd	Change directory	cd /var/log
File Management	pwd	Show current directory	pwd
File Management	mkdir	Create directory	mkdir devops
File Management	rmdir	Remove empty directory	rmdir testdir
File Management	rm	Remove files/directories	rm -rf logs/
File Management	cp	Copy files	cp file1.txt file2.txt
File Management	mv	Move/rename files	mv old.txt new.txt
File Management	touch	Create empty file	touch app.log
File Management	find	Search files	find / -name app.log

2. File Viewing & Text Processing

cat – view file content
less – paginated file view
more – view file content
head – first 10 lines
tail – last 10 lines
tail -f – live log monitoring
grep – search text patterns
cut – extract columns
awk – text processing
sed – stream editor

Category	Command	Purpose	Example
File Viewing	cat	Display file content	cat file.txt
File Viewing	less	View file page by page	less /var/log/syslog
File Viewing	more	View file content	more file.txt
File Viewing	head	Show first lines	head -10 file.txt
File Viewing	tail	Show last lines	tail -10 file.txt
File Viewing	tail -f	Monitor logs live	tail -f app.log

3. Permissions & Ownership

chmod – change permissions
chown – change owner
chgrp – change group
umask – default permissions

Category	Command	Purpose	Example
Permissions	chmod	Change permissions	chmod 755 script.sh
Permissions	chown	Change owner	chown user:user file.txt
Permissions	chgrp	Change group	chgrp devops file.txt
Permissions	umask	Default permissions	umask 022

Category	Command	Purpose	Example
Text Processing	grep	Search patterns	grep "error" app.log
Text Processing	cut	Extract columns	cut -d":" -f1 /etc/passwd
Text Processing	awk	Process text	awk '{print $1}' file.txt
Text Processing	sed	Edit streams	sed 's/error/warning/g' file.txt

4. Process Management

ps – running processes
top – live process monitoring
htop – advanced process viewer
kill – terminate process
killall – kill by name
nice – set process priority
renice – change priority

Category	Command	Purpose	Example
Process	ps	Show processes	ps aux
Process	top	Monitor processes	top
Process	htop	Interactive monitor	htop
Process	kill	Kill process	kill 1234
Process	killall	Kill by name	killall nginx
Process	nice	Set priority	nice -n 10 command
Process	renice	Change priority	renice 5 -p 1234

5. Networking

ifconfig / ip a – network interfaces
ping – test connectivity
curl – API/URL requests
wget – download files
netstat – network connections
ss – socket statistics
scp – secure file copy
ssh – remote login
traceroute – network path tracing

Category	Command	Purpose	Example
Networking	ip a	Show IP address	ip a
Networking	ping	Test connectivity	ping google.com
Networking	curl	HTTP requests	curl http://example.com
Networking	wget	Download files	wget http://file.com/app.zip
Networking	netstat	Network connections	netstat -tulnp
Networking	ss	Socket stats	ss -tuln
Networking	scp	Secure copy	scp file.txt user@host:/tmp
Networking	ssh	Remote login	ssh user@192.168.1.10
Networking	traceroute	Trace route	traceroute google.com

6. Disk & Storage

df -h – disk usage
du -sh – directory size
lsblk – block devices
mount – mount filesystem
fdisk – disk partitioning

Category	Command	Purpose	Example
Disk Usage	df -h	Disk usage	df -h
Disk Usage	du -sh	Directory size	du -sh /var/log
Disk Usage	lsblk	Block devices	lsblk
Disk Usage	mount	Mount filesystem	mount /dev/sdb1 /mnt
Disk Usage	fdisk	Disk partition	fdisk -l

7. System & Package Management

uname -a – system info
uptime – system uptime
free -m – memory usage
systemctl – service management
apt/yum/dnf – package management

Category	Command	Purpose	Example
System	uname -a	System info	uname -a
System	uptime	System uptime	uptime
System	free -m	Memory usage	free -m
System	systemctl	Service management	systemctl status nginx
System	env	Environment variables	env

Bonus (Very Important for DevOps)

• journalctl – system logs
• crontab – scheduled jobs
• docker – container management
• kubectl – Kubernetes control
• env – environment variables

Mandatory Skills for AWS Cloud Engineer (Fresher Level)

1. Core AWS Services — Must Know
2. Linux + Networking Fundamentals
3. Hands-on Practical Skills
4. CI/CD + DevOps Basics (Highly Demanded)
   
5. Programming / Scripting
6. Soft Skills for Cloud Interviews

1. Core AWS Services — Must Know

Category	AWS Service	What to Know
Compute	EC2	Launching servers, SSH, AMI, instance types
Storage	S3	Buckets, versioning, policies, lifecycle
Networking	VPC	Subnets, NAT, Security Groups, Route tables
IAM	IAM	Users, roles, policies, MFA
Databases	RDS	MySQL/PostgreSQL, backups, Multi-AZ
Serverless	Lambda	Triggers, Lambda execution role
Containers (Bonus)	ECS/EKS	Basics of Docker deployment
Load Balancing	ELB/ALB	Routing traffic, health checks
Monitoring	CloudWatch	Logs, alarms, metrics
Automation	CloudFormation/IaC	Deploying infra via code

2. Linux + Networking Fundamentals

Mandatory Basics:

• Linux commands (SSH, file management, permissions)
• Subnetting, IP, DNS, NAT, Load Balancer
• Firewall vs Security Groups

✅ You will run most AWS workloads on Linux.

• File & Directory Management- ls, cd, pwd, mkdir, rmdir, rm, cp, mv, touch, find
• File Viewing & Text Processing- cat, less, more, head, tail, tail -f, grep, cut, awk, sed
• Permissions & Ownership- chmod, chown, chgrp, umask
• Process Management- ps, top, htop, kill, killall, nice, renice
• Networking- ipconfig/ip a, ping, curl, wget, netstat, ss, scp, ssh, traceroute
• Disk & Storage-df -h, du -sh, lsblk, mount, fdisk
• System & Package Management- uname -a, uptime, free -m, systemctl, apt/yum/dnf
• Other Bonus (Very Important for DevOps)- journalctl, crontab, docker, kubectl, env

3. Hands-on Practical Skills-

• Host a website: S3 website hosting, EC2 Webserver (Apache), connect EC2 to RDS, Domain+SSL+ ACM
• Secure infrastructure: IAM roles vs policies
• Automation: Create VPC using Terraform, CI/CD Pipeline using Codepipeline+ GitHub

4. CI/CD + DevOps Basics (Highly Demanded)

• Git + GitHub + GitLab (Must)
• Docker Fundamentals
• AWS Pipeline/Jenkin

5. Programming / Scripting- 

1. Python for AWS
2. Bash for Automation

6. Soft Skills for Cloud Interviews

What is AWS S3?

AWS S3 (Simple Storage Service) is like Google Drive / Dropbox, but for applications and companies.

You can store:

• 📄 Files (PDF, Word, Excel)
• 🖼 Images
• 🎵 Audio / 🎥 Videos
• 🗂 Backups
• 🌐 Website files (HTML, CSS, JS)

S3 = Online storage on AWS cloud

Basic S3 terms (must know)

👉 Bucket = Folder
 👉 Object = File

Step 1: Create AWS Account

Create & Login AWS account.

Step 2: Login to AWS Console

1. Login to 👉 https://console.aws.amazon.com
2. In search bar, type S3
3. Click S3

You will see Amazon S3 dashboard

Step 3: Create Your First S3 Bucket

1. Click Create bucket
2. Fill details:

Bucket name

• Must be unique globally
• Example:demo-bucket-2026

Region

• Choose Asia Pacific (Mumbai) (best for India)

1. Leave all settings default
2. Scroll down → Click Create bucket

🎉 Bucket created!

Step 4: Upload Files to S3 Bucket

1. Click your bucket name
2. Click Upload
3. Click Add files
4. Select any file (PDF, image, mp3)
5. Click Upload

✅ File uploaded successfully

Step 5: Access File (Public or Private)

By default → files are PRIVATE

To make file public:

1. Click on uploaded file
2. Go to Permissions
3. Click Edit
4. Enable:☑ Read – Everyone (public access)
5. Save changes

Now click Object URL

🔗 Anyone can open/download the file

Step 6: Folder Structure in S3 (Important)

You can create folders:

1. Inside bucket → Click Create folder
2. Name:

• images/ documents/ backups/

Upload files inside folders → clean structure

Step 7: Delete File or Bucket

Delete file

• Select file → Delete

Delete bucket

• Empty bucket first
• Then delete bucket

Step 8: Common Real-Life Uses of S3

 ✔ Website images & videos
 ✔ Resume & document storage
 ✔ App file uploads
 ✔ Backup of databases
 ✔ Static website hosting

Step 9: Simple S3 Pricing (Easy)

Free Tier (12 months):

• 5 GB storage free
• 20,000 GET requests free

After free tier:

• Very cheap (₹1–₹2 per GB/month approx)

💡 You only pay for what you use

Step 10: Next Level (Optional — After Basics)

Once comfortable, learn:

• S3 + EC2 (server)
• S3 + CloudFront (fast delivery)
• S3 lifecycle rules (auto delete old files)
• S3 IAM permissions (security)

One-Line Summary

AWS S3 is cloud storage where you create buckets, upload files, control access, and pay only for usage.

S3 Structure

AWS S3
 └── Bucket (Main Folder)
 ├── images/
 │ ├── logo.png
 │ └── banner.jpg
 │
 ├── documents/
 │ ├── resume.pdf
 │ └── invoice.docx
 │
 └── backup.zip

📌 Rules

• One Bucket
• Inside bucket → Folders
• Inside folders → Files (Objects)

4-Months AWS Learning Plan (Weekly Tasks)

📌 Month 1 — Foundations (Cloud + Linux + Networking + IAM)

🎯 End of Month Project:
Static Website deployed on EC2 + Custom VPC

📌 Month 2 — Core AWS Services (Compute + Storage + DB + Monitoring)

AWS Mandatory Technical Skills for Freshers (Core Requirements)

1️⃣ Cloud Basics (AWS Fundamentals)

You should clearly understand:

• What is cloud computing? (IaaS, PaaS, SaaS)

• Why AWS? Benefits & Global Infrastructure

• Regions, Availability Zones, Edge Locations

• Shared Responsibility Model (AWS vs Customer responsibilities)

• Pricing & Cost optimization basics

2️⃣ Key AWS Services (Hands-on Skills → must do)

You should have practical experience deploying a basic project using:

Area	AWS Services to Learn	What to Practice
Compute	EC2	Launch Linux VM, Key pairs, Security Groups
Storage	S3	Host static website, object versioning & lifecycle rules
Networking	VPC, Subnets, Route Tables, NAT Gateway, Security Groups	Create a VPC with public & private subnets
IAM & Security	IAM Users, Roles, Policies, MFA	Secure access, least privilege
Databases	RDS (MySQL/PostgreSQL)	Create DB instance, connect from EC2
Monitoring	CloudWatch	Alarms for EC2/S3
Load Balancing	ELB + Auto Scaling	Deploy 2 instances behind Load Balancer

👉 If you can deploy a 2-tier architecture (EC2 + RDS + ALB + VPC + S3), you’re interview-ready.

3️⃣ Linux + Networking (Compulsory)

Because AWS heavily uses Linux…

✅ Linux Commands:
cd, ls, mkdir, cp, mv, chmod, chown, grep, top, ps, tail, vi

✅ Networking Fundamentals:

• DNS, DHCP, IP addressing, Subnetting

• HTTP/HTTPS protocols

• Firewall/Security Groups

4️⃣ DevOps Basics (Beginner Level Required)

Companies expect automation knowledge:

• CI/CD basics

• Git & GitHub workflow

• Shell scripting (basic level)

• Terraform (optional but gives advantage)

• AWS CLI + SDK basics

5️⃣ Database Skills

• Difference between SQL vs NoSQL

• Basic CRUD in MySQL

• DynamoDB basics (bonus)

Bonus Skills That Increase Job Selection Chances

One Mini Project You MUST Build (Interview Portfolio)

📌 Deploy a web app with the below:

• Frontend static files on S3 + CloudFront

• Backend on EC2 inside a VPC

• Database on RDS

• IAM roles for secure access

• ALB + Auto Scaling

• Monitoring using CloudWatch

• Source on GitHub

➡ Interviewer will be impressed if you can explain architecture diagram + security setup.

Sample Interview Questions You Must Prepare

✅ Cloud / AWS

• What is difference between EC2 and Lambda?

• Public vs Private subnet?

• How does Auto Scaling work?

• RTO and RPO?

✅ Networking

• CIDR notation?

• What are security groups vs NACL?

✅ Linux

• How to check running processes?

• File permissions meaning like drwxr-xr--?

✅ Practical Demo (very common)

• Launch EC2 + install a web server

• Upload objects to S3 & set access permissions

Final Roadmap (2 Months Plan)

Month	Focus
1-	Linux + AWS Core Services + VPC + IAM hands-on
2-	RDS + Load Balancing + Git + Mini Project + Interview Q&A

Checklist of main requirements for Website SEO

 1. Technical SEO Requirements

Ensure your website is technically optimized so that search engines can easily crawl, index, and rank it.

✅ Website Structure & Crawlability

• Create a clear site architecture with easy navigation and logical URL hierarchy.

• Use an XML sitemap and submit it to Google Search Console & Bing Webmaster Tools.

• Add a robots.txt file to control what search engines can crawl.

• Ensure HTTPS (SSL certificate) is active for security and trust.

• Implement canonical tags to prevent duplicate content issues.

⚡ Speed & Performance

• Optimize page loading speed (under 3 seconds ideally).

• Use tools like Google PageSpeed Insights or GTmetrix to test and improve.

• Compress images and enable browser caching.

• Use a Content Delivery Network (CDN) for faster delivery.

📱 Mobile Optimization

• Ensure the site is mobile-friendly and responsive.

• Test using Google’s Mobile-Friendly Test Tool.

📊 Indexing & Monitoring

• Verify your site on Google Search Console.

• Regularly check for crawl errors and index coverage.

• Use structured data (Schema Markup) for rich snippets (e.g., FAQ, Product, LocalBusiness).

---

🏷️ 2. On-Page SEO Requirements

These help search engines understand what each page is about.

📝 Content Optimization

• Use unique, valuable, and keyword-rich content on each page.

• Maintain a keyword density of around 1–2%.

• Add LSI (Latent Semantic Indexing) keywords and related terms.

• Use internal links to related pages and blogs.

• Optimize for featured snippets (use bullet points, Q&A format).

🔑 Meta Tags

• Write unique meta titles (under 60 characters) with focus keywords.

• Create meta descriptions (under 160 characters) encouraging clicks.

• Use H1 for main headings and H2/H3 for subheadings.

🌐 URLs

• Keep URLs short, clean, and keyword-focused (e.g., example.com/labour-law-compliance).

• Use hyphens (-) instead of underscores (_) in URLs.

🖼️ Images & Media

• Optimize image size and use descriptive file names.

• Add ALT text with keywords for accessibility and SEO.

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📢 3. Off-Page SEO Requirements

These build domain authority and trust externally.

🔗 Backlinks

• Build high-quality backlinks from authoritative websites.

• Use guest blogging, press releases, or directory submissions (only credible ones).

• Avoid spammy or low-quality link sources.

💬 Social Media & Branding

• Maintain active social media profiles linking back to your website.

• Encourage social sharing of your blog posts and pages.

• Ensure consistent NAP (Name, Address, Phone) details across all platforms (important for Local SEO).

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🗺️ 4. Local SEO (If applicable)

If your business serves specific regions (like Delhi NCR, India).

• Create and optimize your Google Business Profile (GMB).

• Add local schema markup (LocalBusiness, ServiceArea).

• Encourage customer reviews and respond promptly.

• Include location-based keywords (e.g., “Labour Law Compliance Consultants in Delhi NCR”).

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✍️ 5. Content & Blog Strategy

• Maintain an active blog with fresh, relevant topics.

• Use keyword research tools (Google Keyword Planner, Ahrefs, SEMrush).

• Include internal and external links in blogs.

• Add CTA (Call-to-Action) for conversions.

• Update older posts regularly.

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🧭 6. Analytics & Performance Tracking

• Set up Google Analytics and Google Tag Manager.

• Track organic traffic, bounce rate, and conversion goals.

• Monitor keyword rankings using tools like Ahrefs, SEMrush, or Ubersuggest.

• Analyze backlinks and competitor SEO regularly.

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🛠️ 7. Ongoing SEO Maintenance

• Perform monthly audits for broken links, page speed, and ranking drops.

• Keep up with Google algorithm updates.

• Refresh meta tags and content periodically.

• Continue link building and local citations.

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#SearchEngineOptimization
#DigitalMarketing
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#WebsiteOptimization
#GoogleRanking
#SearchRanking
#WebsiteTraffic
#SearchVisibility
#SEOTips

#TechnicalSEO

#WebsiteSpeed
#MobileSEO
#SiteAudit
#PageSpeedOptimization
#CoreWebVitals
#WebsiteSecurity
#SchemaMarkup
#CrawlOptimization
#SEOAudit

#OnPageSEO

#MetaTags
#KeywordOptimization
#ContentOptimization
#SEOContentWriting
#InternalLinking
#ContentMarketing
#SEOFriendlyContent
#SEOBestPractices

#OffPageSEO

#LinkBuilding
#Backlinks
#DomainAuthority
#LocalSEO
#GoogleMyBusiness
#LocalSearch
#NAPConsistency
#SEOForBusiness

Performance & Strategy Hashtags

#Analytics
#DigitalStrategy
#MarketingStrategy
#SearchEngineMarketing
#WebsiteAnalytics
#SEOResults
#GoogleAnalytics
#SEOServices
#SEOExperts

Business & Branding Hashtags (for Corporate Use)

#CorporateSEO
#BusinessGrowth
#OnlinePresence
#BrandVisibility
#DigitalPresence
#SEOForBusiness
#MarketingForCorporates
#SankhlaCorporateServices