Claude Code Cheatsheet

# macOS, Linux, WSL (recommended)
curl -fsSL https://claude.ai/install.sh | bash

# Homebrew
brew install --cask claude-code

# npm (global)
npm install -g @anthropic-ai/claude-code

# PowerShell (Windows)
irm https://claude.ai/install.ps1 | iex

claude update
claude --version

claude
claude "explain this codebase"
claude --continue
claude --resume <session-id>

/config                 # open the settings screen
/config model=sonnet    # set a value directly
/config theme=dark
/config --help          # list the keys you can set

{
  "model": "sonnet",
  "permissions": {
    "allow": ["Bash(npm test *)", "Bash(git diff *)"]
  }
}

---
description: "Run all linters and fix auto-fixable issues"
allowed-tools: Bash
---

1. `npm run lint -- --fix`
2. `npm run type-check`
3. Summarise what was fixed.

claude -p "summarise the last commit"
cat README.md | claude -p "check for spelling errors"
claude -p "list all TODO comments" --output-format json
claude -p "explain main.go" --output-format stream-json

# CI: fail if tests broken
claude -p "run tests and exit 1 if any fail" --allowedTools Bash

# Nightly summary
git log --since=yesterday --oneline | \
  claude -p "plain-English summary of today's commits" > summary.txt

# Auto PR review
gh pr diff | claude -p "review for bugs and security issues"

---
description: "Stage all changes and create a conventional commit"
allowed-tools: Bash, Read, Glob
argument-hint: "[optional: commit message]"
---

1. Run `git diff --staged` and `git status`.
2. If nothing is staged, run `git add -A`.
3. Write a conventional commit message.
4. Run `git commit -m "<message>"`.

---
description: "Review current branch diff for bugs and style issues"
allowed-tools: Bash, Read
---

1. Run `git diff main...HEAD`.
2. Check for: bugs, security, missing error handling, style.
3. Output grouped by severity.

claude plugins list
claude plugins install <plugin-name>
claude plugins install ./my-plugin
claude plugins remove <plugin-name>
claude plugins update

my-plugin/
├── plugin.json
├── commands/
│   └── my-skill.md
└── mcp/
    └── my-server.json

{
  "name": "my-plugin",
  "version": "1.0.0",
  "description": "My custom plugin",
  "commands": ["commands/my-skill.md"],
  "mcpServers": ["mcp/my-server.json"]
}

claude mcp add <name> <command> [args...]
claude mcp add filesystem npx -y @modelcontextprotocol/server-filesystem /path
claude mcp remove <name>
claude mcp list

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path"],
      "env": {}
    }
  }
}

git worktree list
git worktree add ../feature-branch feature-branch
git worktree add -b my-feature ../my-feature main
git worktree remove ../feature-branch
git worktree prune

# Terminal 1
git worktree add -b feat/auth ../project-auth main
cd ../project-auth && claude

# Terminal 2
git worktree add -b fix/perf ../project-perf main
cd ../project-perf && claude

/worktree my-feature-name
# Creates .claude/worktrees/my-feature-name and switches into it

---
description: "Deep code review: bugs, security, style"
allowed-tools: Read, Glob, Grep
---

Review the provided diff for:
- Logic bugs and edge cases
- Security vulnerabilities (OWASP Top 10)
- Performance issues

Output a markdown report with severity labels.

---
description: "Root-cause analysis for failing tests or errors"
allowed-tools: Read, Bash, Grep, Glob
---

1. Reproduce the error.
2. Identify the root cause.
3. Propose the minimal fix.
4. Verify the fix doesn't break other tests.

---
description: "Analyse data files and produce statistical summaries"
allowed-tools: Bash, Read
---

1. Load and describe the schema.
2. Identify missing values and outliers.
3. Compute summary statistics.
4. Suggest visualisations and next steps.

{
  "permissions": {
    "allow": ["Read", "Write", "Edit", "Bash(git *)"],
    "deny": ["Bash(rm -rf *)", "Bash(curl *)", "Bash(wget *)"]
  }
}

{
  "permissions": {
    "allow": ["Read", "Glob", "Grep"],
    "deny": ["Write", "Edit", "Bash", "WebFetch", "WebSearch"]
  },
  "autoApprove": false
}

{
  "permissions": {
    "allow": ["Read","Write","Edit","Glob","Grep",
      "Bash(npm *)","Bash(git *)","Bash(docker *)"],
    "deny": ["Bash(curl *)","Bash(wget *)","Bash(ssh *)","WebFetch"]
  },
  "autoApprove": false,
  "requireApprovalForNewFiles": true
}

{
  "hooks": {
    "PostToolUse": [{
      "matcher": "Bash",
      "hooks": [{ "type": "command",
        "command": "echo '$CLAUDE_TOOL_INPUT' >> ~/.claude/bash-log.txt" }]
    }],
    "Stop": [{
      "hooks": [{ "type": "command",
        "command": "osascript -e 'display notification \"Claude finished\"'" }]
    }]
  }
}

"PreToolUse": [{ "matcher": "Bash", "hooks": [{
  "type": "command",
  "command": "if echo \"$CLAUDE_TOOL_INPUT\" | grep -qE 'rm -rf|DROP TABLE'; then exit 1; fi"
}]}]