The CLI Interface

Claude Code lives in your terminal. Understanding the interface is the first step to using it effectively.

Launching Claude

# Interactive mode (most common)
claude

# One-shot mode (run a single prompt and exit)
claude -p "explain this error log"

# Pipe input to Claude
cat error.log | claude -p "what went wrong?"

# Resume your last conversation
claude --continue

The Interactive Prompt

When you run claude, you get an interactive session:

> _

This is where you type natural language instructions. Claude reads your message, decides what tools to use, and takes action.

Key Keyboard Shortcuts

Shortcut	Action
`Enter`	Send message
`Shift+Enter`	New line (multi-line input)
`Ctrl+C`	Cancel current operation
`Ctrl+D`	Exit Claude Code
`/`	Open slash command menu

Slash Commands

Type / to see available commands:

/help — show help
/clear — clear conversation history
/compact — compress conversation to save context
/model — switch models mid-session
/cost — show token usage and cost
/memory — manage Claude’s project memory

Understanding Tool Calls

When Claude works, you’ll see tool calls in your terminal:

Claude: I'll create that file for you.

📝 Write: src/index.html
───────────────────────
<html>
  <body>Hello World</body>
</html>
───────────────────────

Allow? [y/n]

Each tool call shows:

What tool is being used (Read, Write, Edit, Bash, etc.)
What it will do (the file path, command, etc.)
A preview of the content or command
A permission prompt (unless you’ve pre-approved it)

Permission Modes

Claude Code has three permission modes:

Ask every time (default) — you approve each tool call
Allow specific tools — pre-approve safe operations like file reads
YOLO mode — auto-approve everything (use with caution!)

Configure permissions in ~/.claude/settings.json or per-project in .claude/settings.json.

Context Window

Claude has a context window limit. As your conversation grows, earlier messages get compressed. The /compact command forces this compression, which is useful when:

You’re running low on context
The conversation has drifted from the original topic
You want to “reset” while keeping key information

Tips

Use one-shot mode for quick questions: claude -p "what does this regex do: ^[a-z]+$"
Use --continue to pick up where you left off after closing your terminal
Watch the cost with /cost — Opus is powerful but uses more tokens