We've all been there: you're SSH'd into a production server at 11 PM, you need that one command you've used a hundred times, and your brain just... blanks. So you open a browser, fight through documentation, and waste five minutes finding a one-liner.
I got tired of this. So I built a free library of 121 professional PDF guides organized across 4 skill levels, covering 40+ technologies. No paywalls, no "premium tier," no bait-and-switch.
Here's what's inside and why I structured it this way.
The Problem with Most Cheat Sheets
Most cheat sheets online fall into one of two categories:
- Too shallow — a random list of 10 commands that doesn't cover what you actually need
- Too dense — a wall of text that's harder to navigate than the official docs
And almost none of them address the fact that a junior admin and a senior architect need completely different references for the same technology.
That's why I built 4 distinct tiers.
The 4 Tiers
Tier 1: Quick Reference (41 sheets)
One-page PDFs. The commands you actually use, organized for instant lookup. Designed to be printed and pinned next to your monitor.
Perfect for: daily work, team onboarding, interview prep
Technologies covered:
- Linux & Systems: Linux Commands, File Permissions, Bash Scripting, Vim/Nano, SSH, Systemd & Journalctl
- Containers: Docker, Docker Compose, Kubernetes kubectl, K8s YAML, Helm
- Cloud & IaC: AWS CLI, Azure CLI, Terraform, Ansible, Nginx, Apache HTTPD
- Databases: PostgreSQL, MySQL, SQL, MongoDB, Redis, Elasticsearch
- Languages: Python, JavaScript, TypeScript, Go, Rust, Java, PHP, Ruby, C/C++, Node.js, HTML/CSS
- DevOps & Tools: Git, GitHub Actions, Jenkins, PowerShell, Regex, Networking, Kafka
Every sheet follows the same format: real-world commands grouped by task, no fluff, designed for one-page printing.
Browse all 41 Quick Reference sheets →
Tier 2: Beginner's Complete Guides (40 guides)
These are not cheat sheets — they're structured learning resources that start from "what is this technology?" and build up step by step. Zero prerequisites. Every concept includes working examples and real scenarios.
Perfect for: career changers, juniors, anyone picking up a new technology
Every technology from the Quick Reference collection has a matching Beginner's Guide. Some highlights: Linux from first terminal command, Docker from scratch, Kubernetes pods-to-deployments, Python fundamentals, Git from first commit, PostgreSQL from first query.
Recommended learning paths:
| Goal | Path |
|---|---|
| Linux Sysadmin | Linux → Permissions → Bash → SSH → Systemd → Networking → Nginx |
| DevOps Engineer | Linux → Git → Docker → Compose → K8s → Terraform → Ansible → GitHub Actions |
| Backend Developer | Python or JS → Git → SQL → PostgreSQL → Docker → Redis |
| Cloud Engineer | Linux → Networking → AWS or Azure → Terraform → Ansible → Docker → K8s |
Browse all 40 Beginner's Guides →
Tier 3: Intermediate Guides (20 guides)
The bridge between "it works" and "it works in production." These teach you the patterns that separate hobbyists from professionals.
Perfect for: working professionals with 6-12 months of experience
The mindset shift at this level:
| Beginner approach | Intermediate approach |
|---|---|
| Copy commands from tutorials | Understand what each flag does |
| Fix errors by Googling | Read logs systematically, trace root causes |
| Run everything as root | Least-privilege access, proper user management |
| Store configs locally | Version control everything, use templates |
| Manual deployments | Scripted, repeatable processes |
Available for: Linux, Permissions, Bash, Vim, SSH, Docker, Docker Compose, Kubernetes, AWS, Azure, Terraform, Ansible, Nginx, PostgreSQL, MySQL, Python, Git, PowerShell, Regex, Networking
Key topics include: Docker multi-stage builds and security scanning, Kubernetes RBAC and network policies, PostgreSQL query optimization with EXPLAIN ANALYZE, Terraform modules and state management, Git interactive rebase and bisect debugging.
Browse all 20 Intermediate Guides →
Tier 4: Advanced Guides (20 guides)
For senior engineers who want to understand how things work under the hood. System internals, architecture patterns, performance engineering, and security hardening.
Perfect for: senior/staff engineers, architects, interview prep for principal roles
What's covered:
- Linux kernel tuning (sysctl, cgroups v2, eBPF tracing, custom kernel modules)
- Kubernetes custom controllers/operators, admission webhooks, service mesh
- PostgreSQL WAL internals, logical replication, vacuum tuning, custom extensions
- Docker BuildKit internals, OCI spec, rootless containers, Falco/Seccomp
- Python metaclasses, descriptors, asyncio internals, C extensions
- SSH certificate authority architectures, FIDO2 hardware keys
- Terraform custom providers, state surgery, testing frameworks
- Nginx OpenResty/Lua scripting, HTTP/3 QUIC
Available for: the same 20 core technologies as the Intermediate tier — Linux, Docker, Kubernetes, PostgreSQL, MySQL, Python, Git, AWS, Azure, Terraform, Ansible, Nginx, Bash, SSH, Vim, PowerShell, Regex, Networking, Permissions, Docker Compose.
Browse all 20 Advanced Guides →
Technology Coverage
20 technologies have complete coverage across all 4 levels:
| Technology | Quick Ref | Beginner | Intermediate | Advanced |
|---|---|---|---|---|
| Linux | ✅ | ✅ | ✅ | ✅ |
| Docker | ✅ | ✅ | ✅ | ✅ |
| Kubernetes | ✅ | ✅ | ✅ | ✅ |
| PostgreSQL | ✅ | ✅ | ✅ | ✅ |
| Python | ✅ | ✅ | ✅ | ✅ |
| Git | ✅ | ✅ | ✅ | ✅ |
| Terraform | ✅ | ✅ | ✅ | ✅ |
| AWS | ✅ | ✅ | ✅ | ✅ |
| Nginx | ✅ | ✅ | ✅ | ✅ |
| Ansible | ✅ | ✅ | ✅ | ✅ |
An additional 20 technologies (JavaScript, TypeScript, Go, Rust, Java, Redis, MongoDB, Kafka, etc.) have Quick Reference + Beginner coverage.
See the full technology map with all 40+ technologies →
Why Free?
Because I've been the junior engineer who couldn't afford $200 courses. And I've been the senior engineer who spent hours building personal wikis from scattered blog posts and Stack Overflow answers.
The knowledge exists — it's just scattered across hundreds of documentation pages, blog posts, and forum threads. I organized it into one structured, well-designed, always-available library.
Good technical references shouldn't depend on your employer's training budget.
What's Next
We're actively working on:
- Prometheus & Grafana (monitoring and observability)
- ArgoCD (GitOps continuous delivery)
- Istio (service mesh)
- Go and Rust intermediate + advanced guides
Get the Guides
Everything is available at dargslan.com/cheat-sheets.
Download individual guides or grab the complete bundle for each tier. No credit card needed — just your email so we can notify you when new guides are published.
If these are useful to you, a bookmark or a share goes a long way.
What technology would you like to see covered next? Drop a comment below.
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