20 Linux Administration Tips and Tricks

# Navigate and list files
$ ls -lah
$ cd /var/log
$ pwd

# File operations
$ cp file.txt backup.txt
$ mv oldname.txt newname.txt
$ cat file.txt | grep "error"

💡 See our Linux Commands Cheatsheet for comprehensive reference

# Change file permissions
$ chmod 755 script.sh        # rwxr-xr-x
$ chmod u+x script.sh        # Add execute for user

# Change ownership
$ sudo chown user:group file.txt
$ sudo chown -R www-data:www-data /var/www/

📚 Learn more: Linux File Permissions Cheatsheet

# Generate SSH key pair
$ ssh-keygen -t ed25519 -C "[email protected]"

# Copy public key to server
$ ssh-copy-id user@hostname

# Use ssh-agent for key management
$ eval "$(ssh-agent -s)"
$ ssh-add ~/.ssh/id_ed25519

🔒 Security guide: OpenSSH Server Hardening

# Using firewalld (modern approach)
$ sudo firewall-cmd --list-all
$ sudo firewall-cmd --permanent --add-service=http
$ sudo firewall-cmd --permanent --add-port=8080/tcp
$ sudo firewall-cmd --reload

# Using iptables (legacy)
$ sudo iptables -L -n -v
$ sudo iptables -A INPUT -p tcp --dport 80 -j ACCEPT

🛡️ Full guide: Linux Server Hardening Cheatsheet
🔍 Test your firewall: Port Scanner to verify open ports and firewall configuration

# Using rsync for incremental backups
$ rsync -avz --delete /source/ /backup/
$ rsync -avz -e ssh /local/path/ user@remote:/backup/

# Using tar for compressed backups
$ tar -czf backup-$(date +%Y%m%d).tar.gz /path/to/data/

# Automate with cron (daily at 2 AM)
$ crontab -e
0 2 * * * /usr/local/bin/backup-script.sh

⏰ Automation: Cron Job Cheatsheet | 📦 Archiving: TAR Command Cheatsheet

#!/bin/bash
# Simple backup script
DATE=$(date +%Y%m%d)
BACKUP_DIR="/backup"
SOURCE="/var/www"

# Create backup
tar -czf "$BACKUP_DIR/backup-$DATE.tar.gz" "$SOURCE"

# Keep only last 7 days of backups
find "$BACKUP_DIR" -name "backup-*.tar.gz" -mtime +7 -delete

echo "Backup completed: backup-$DATE.tar.gz"

Pro Tip: Start with simple scripts and gradually add error handling, logging, and notifications. Version control your scripts with Git!

# Debian/Ubuntu
$ sudo apt update && sudo apt upgrade -y
$ sudo apt install nginx -y

# RHEL/CentOS/Fedora
$ sudo dnf update -y
$ sudo dnf install nginx -y

# Search for packages
$ apt search nginx
$ dnf search nginx

# Check connectivity
$ ping -c 4 google.com
$ traceroute google.com

# Check open ports and connections
$ ss -tuln
$ netstat -tuln

# DNS troubleshooting
$ nslookup example.com
$ dig example.com

# Check routing table
$ ip route show

🌐 More commands: Linux Networking Commands | IP Command Reference
🛠️ Diagnostic tools: DNS Lookup for DNS troubleshooting | WHOIS for domain info | What Is My IP to check your server's public IP

# View running processes
$ ps aux
$ ps aux | grep nginx
$ top
$ htop

# Manage services with systemctl
$ sudo systemctl status nginx
$ sudo systemctl start nginx
$ sudo systemctl enable nginx
$ sudo systemctl restart nginx

# Kill processes
$ kill -9 1234
$ killall nginx

# Check disk space
$ df -h
$ df -i  # Check inodes

# Check directory sizes
$ du -sh /var/log
$ du -h --max-depth=1 /var | sort -hr

# Find large files
$ find / -type f -size +100M 2>/dev/null

# Check disk I/O
$ iostat
$ iotop

💾 Advanced: Linux LVM Cheatsheet

# Initialize repository
$ git init
$ git clone https://github.com/user/repo.git

# Basic workflow
$ git status
$ git add .
$ git commit -m "Add new feature"
$ git push origin main

# Branching
$ git checkout -b feature-branch
$ git merge feature-branch

📖 Complete guide: Git Command Cheatsheet

# Docker basics
$ docker run -d -p 80:80 nginx
$ docker ps
$ docker images
$ docker logs container_id
$ docker exec -it container_id bash

# Build custom image
$ docker build -t myapp:latest .
$ docker push myapp:latest

# Docker Compose
$ docker-compose up -d
$ docker-compose logs -f

🐳 Learn more: Docker Reference Sheet | ☸️ Kubernetes Components
🏗️ Container hosting: Container-optimized VPS providers | Docker performance benchmarks

# Ansible example - playbook.yml
---
- hosts: webservers
  become: yes
  tasks:
    - name: Install nginx
      apt:
        name: nginx
        state: present
        update_cache: yes
    
    - name: Start nginx service
      service:
        name: nginx
        state: started
        enabled: yes

# Run playbook
$ ansible-playbook -i inventory.ini playbook.yml

$ aws s3 ls
$ aws ec2 describe-instances

$ az vm list
$ az group create

$ gcloud compute instances list
$ gcloud projects list

☁️ Cloud models: Cloud Platform Models
🏢 Choose hosting: Compare VPS providers | Side-by-side comparison | Cloud VPS performance benchmarks

# Example .gitlab-ci.yml
stages:
  - build
  - test
  - deploy

build_job:
  stage: build
  script:
    - docker build -t myapp:$CI_COMMIT_SHA .
    - docker push myapp:$CI_COMMIT_SHA

test_job:
  stage: test
  script:
    - pytest tests/

deploy_job:
  stage: deploy
  script:
    - kubectl set image deployment/myapp myapp=myapp:$CI_COMMIT_SHA
  only:
    - main

📊 Log parsing: Linux Log Parsing Commands
📈 Monitor your infrastructure: Dashboard for real-time metrics | Performance benchmarks to track VPS health

# Terraform example - main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.0"
    }
  }
}

resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t2.micro"

  tags = {
    Name = "WebServer"
  }
}

# Commands
$ terraform init
$ terraform plan
$ terraform apply

# Kubernetes deployment
$ kubectl create deployment nginx --image=nginx
$ kubectl expose deployment nginx --port=80 --type=LoadBalancer
$ kubectl scale deployment nginx --replicas=3
$ kubectl get pods
$ kubectl logs pod-name
$ kubectl describe deployment nginx

☸️ Deep dive: Kubernetes Components Cheatsheet