Installing and Using Claude Code CLI

Claude Code is Anthropic's terminal-native coding agent. Let's install it, wire it to a project, and use the features most engineers miss on day one.

50 min · Reviewed 2026

A Coding Agent That Lives in Your Shell

Claude Code is a terminal-based agent that reads and writes files, runs commands, and carries project context across sessions. Unlike an IDE plugin, it can drive your entire development environment, not just the editor.

Install in under two minutes

# Install globally via npm npm install -g @anthropic-ai/claude-code # First run — authenticates via browser cd my-project claude # Inside the TUI, type your first request: # "Explain what this repo does and list the main entry points."Two commands and you are running an agent against your codebase.

CLAUDE.md: project memory

Drop a CLAUDE.md file at the root of your project. Claude Code reads it on every session. This is where you put your project's conventions, scripts to run, architecture notes, and the AI etiquette you want followed. Teams treat it as a living style guide.

# CLAUDE.md ## Stack - Next.js 15, TypeScript, Tailwind, Postgres via Prisma. ## How to run - `pnpm dev` for local, `pnpm test` for tests, `pnpm build` before PR. ## Conventions - Server actions live in `app/actions/`, named `<verb><Noun>`. - Never commit directly to main — always open a branch. - Use Zod for all public API inputs. ## Things to avoid - Do not add new dependencies without asking first. - Do not rename exported functions — downstream consumers break.A CLAUDE.md is the single highest-leverage file in any Claude Code project.

Slash commands and skills

As of 2026, slash commands and skills are unified in Claude Code. Put markdown files in .claude/skills/ at the project root, and each one becomes a /slash-command. The skill defines a repeatable workflow: run tests, deploy, generate a PR description, whatever you need.

# .claude/skills/pr-ready.md --- name: pr-ready description: Prepare the branch for PR review --- 1. Run `pnpm lint --fix` and commit any fixes. 2. Run `pnpm test` and make sure all pass. 3. Run `pnpm build` and fix any type errors. 4. Write a PR description summarizing the diff in 3 bullets. 5. Suggest a PR title under 70 characters.Now typing /pr-ready in any Claude Code session triggers this playbook.

Sub-agents: up to 10 in parallel

A sub-agent is a separate Claude instance spawned from your main session to handle a narrow job. Define one in .claude/agents/explore.md with its own tool access and system prompt. Then say: Use the explore agent to find all auth-related files. Up to 10 can run in parallel, which is a game-changer for parallel codebase exploration.

Day-one workflow

Install, authenticate, cd into your project
Write a CLAUDE.md describing stack, conventions, and commands
Ask Claude to explain the repo architecture out loud
Create one skill for a workflow you repeat (tests, deploy, etc.)
Ask Claude to plan a feature, then execute step by step

The best interface is the one that can drive the whole machine. The terminal still is.
— A Unix-pilled engineer

The big idea: Claude Code treats your terminal as the agent's workspace. CLAUDE.md gives it context, skills automate recurring work, and sub-agents run parallel tasks. Invest in those three and the tool compounds.

End-of-lesson check

8 questions · take it digitally for instant feedback at tendril.neural-forge.io/learn/quiz/end-coding-installing-claude-code-creators

What is the main idea of "Installing and Using Claude Code CLI"?
1. Claude Code is Anthropic's terminal-native coding agent. Let's install it, wire it to a project, and use the features most engineers miss on day one.
2. Use AI as the final authority for the whole decision
3. Avoid checking the answer once it sounds polished
4. Focus only on speed instead of judgment
Which concept is most central to "Installing and Using Claude Code CLI"?
1. CLAUDE.md
2. Claude Code
3. slash commands
4. skills
Which use of AI fits this topic best?
1. Let the AI decide what matters without your review
2. Use the answer before checking whether it fits the situation
3. Install, authenticate, cd into your project
4. Treat the AI output as automatically correct
What should a careful learner remember about "Hooks let you automate reactions"?
1. Use AI to draft or organize ideas about Claude Code, then verify before acting.
2. Skip the context so the tool can guess faster
3. Treat the output as private even after sharing it online
4. Use the answer without checking the source
You want to use AI after this lesson. What is the safest next step?
1. Act immediately because the AI answer is written clearly
2. Use AI for drafting and comparison, but verify before publishing or relying on it.
3. Hide uncertainty so the final answer looks cleaner
4. Use private or sensitive details before checking permission
How should AI output about Claude Code be treated?
1. As proof that no other source is needed
2. As a replacement for context, consent, or expert review
3. As a draft or helper output that still needs human judgment and verification
4. As something that becomes correct when it sounds confident
Name one way to verify an AI answer about Claude Code.
Which action would help you apply "Installing and Using Claude Code CLI" responsibly?
1. Use the tool to avoid thinking through the tradeoff
2. Keep going even if the output conflicts with a trusted source
3. Treat the AI output as automatically correct
4. Write a CLAUDE.md describing stack, conventions, and commands

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