You Don’t Need LeetCode – You Need to Rebuild These 3 CLI Tools

You Don’t Need LeetCode – You Need to Rebuild These 3 CLI Tools

By Ebuka Onah

Most developers obsess over algorithm puzzles that never show up in real jobs. Meanwhile, the tools you actually use every day are sitting there waiting to be understood at a deeper level.

If you want real engineering skill—not interview theater—you should rebuild tools that actually run the world.

Real skill is not solving toy problems. It is understanding the systems you already depend on.

1. Rebuild grep – The Pattern Engine of the Terminal

grep is one of the most powerful text-search tools ever built. It scans files and streams for patterns at incredible speed.

Rebuilding it teaches:

  • String parsing at scale
  • Regular expressions
  • File streaming and buffering
  • Performance optimization
input: logs.txt
pattern: "ERROR"

output: all matching lines
If you understand grep deeply, you understand how logs, search, and debugging actually work.

2. Rebuild jq – JSON Is the Real Database

jq is a command-line processor for JSON. It lets you filter, transform, and reshape structured data instantly.

Rebuilding it teaches:

  • Tree traversal
  • Parsing nested data structures
  • Functional transformation pipelines
  • Data serialization logic
{
  "user": {
    "name": "Ebuka",
    "role": "developer"
  }
}

Extract name → transform output → reshape structure.

Modern backend work is basically JSON manipulation at scale.

3. Rebuild htop – Understanding What Your Machine Is Doing

htop is a real-time system monitor. It shows CPU usage, memory, and running processes.

Rebuilding it teaches:

  • Operating system fundamentals
  • Process management
  • Memory usage tracking
  • Real-time UI updates in terminal
CPU: 45%
Memory: 3.2GB used
Processes: 182 running
If you don’t understand your system, you can’t debug performance problems properly.

Why This Beats LeetCode

LeetCode trains pattern recognition for interviews. CLI rebuilding trains engineering intuition for real systems.

  • LeetCode = artificial constraints
  • CLI tools = real-world complexity
  • LeetCode = isolated problems
  • CLI tools = connected systems
One builds interview confidence. The other builds engineering depth.

How to Actually Do This

You don’t need to rebuild everything perfectly. You need to understand how it works step by step.

  1. Start with a simple version
  2. Add one feature at a time
  3. Test with real data
  4. Optimize only after correctness

Final Insight

Most developers are optimizing for interviews. Very few are optimizing for understanding systems.

That gap is where real engineers are built.

Stop practicing puzzles. Start rebuilding tools that already power the world.