Module 1: Foundations — Reference Materials

This document compiles the essential information you need to get started with Claude Code. Refer to it whenever you get stuck or need to look up a command.

Audience: Tech-savvy individuals who have no prior experience with the CLI or programming

Table of Contents

• 1. Claude Code Basic Commands (Slash Commands)
• 2. Common Terminal Commands
• 3. Glossary
• 4. FAQ (Frequently Asked Questions)
• 5. Troubleshooting

1. Claude Code Basic Commands (Slash Commands)

This is a list of slash commands you can use inside Claude Code. When you see the > prompt, type a command starting with / to use it.

Basic Commands

Conversation Management Commands

Settings & Information Commands

Project Management Commands

Startup Options

These are options you can add when launching claude from the terminal.

Responding to Permission Prompts

When Claude Code asks for confirmation before performing file operations or running commands, here is how to respond.

Keyboard Shortcuts (Inside Claude Code)

Tip: Anything starting with / is a slash command. Regular text in your language is treated as an instruction to Claude Code.

2. Common Terminal Commands

These are basic commands you use in the terminal (outside of Claude Code, on the regular command line). This is a curated list of the minimum commands that are useful to know when working with Claude Code.

Check Where You Are

What it stands for: pwd = Print Working Directory

This command tells you “where you currently are” on your computer. If you ever feel lost, just run pwd.

View Folder Contents

What it stands for: ls = List

On Windows: In PowerShell, you can use dir instead of ls for the same result.

Navigate Between Folders

What it stands for: cd = Change Directory

Analogy: Think of cd like taking an elevator in a building. cd Documents is “go to the Documents floor,” cd .. is “go down one floor,” and cd ~ is “go back to the ground floor (home).”

Work with Files and Folders

What they stand for:

• mkdir = Make Directory
• cat = Concatenate (originally for joining files; commonly used to display file contents)
• cp = Copy
• mv = Move
• rm = Remove

Warning: Files deleted with rm do not go to the Recycle Bin and cannot be recovered. Always back up important files before deleting them.

How to Read Paths

A path is the “address” of a file or folder.

/home/yuichiro/Documents/project/report.md
 |      |         |         |        |
 |      |         |         |        └── File name
 |      |         |         └── Project folder
 |      |         └── Documents folder
 |      └── User's folder
 └── Root (top level)

Keyboard Shortcuts (In the Terminal)

Tip: The Tab key auto-complete feature is incredibly handy. Type the first few characters of a file name and press Tab to fill in the rest automatically. It helps you avoid typos in file names.

3. Glossary

This glossary explains terms used in Claude Code and this course in a way that is accessible to non-engineers. Entries are sorted alphabetically.

4. FAQ (Frequently Asked Questions)

Q1: Is Claude Code free to use?

A: Installing Claude Code itself is free, but using it requires an Anthropic API key or a subscription plan. With an API key, you pay based on usage (pay-as-you-go). With a Claude Pro or Claude Max plan, you pay a flat monthly fee. You can run the /cost command during a session to check your current usage. Please refer to Anthropic’s official website for the latest pricing.

Q2: Where are files created by Claude Code saved?

A: They are saved in the folder where you launched Claude Code (the current directory). You can check the current folder with the pwd command. If you want to specify a save location, include the folder name or path in your instruction (e.g., “Save it in the reports folder” or “Save it to ~/Documents/”).

Q3: Is it safe to share confidential or personal information with Claude Code?

A: Information you input into Claude Code is sent to Anthropic’s API servers for processing. According to Anthropic’s privacy policy, data sent via the API is not used for model training. However, for highly confidential information or personal data, be sure to check your organization’s security policy. We also recommend not including confidential information in your CLAUDE.md file.

Q4: I gave it the wrong instruction. Can I undo it?

A: In some cases, Claude Code will ask for confirmation before creating or modifying files. At that point, you can choose n (No) to cancel. If the action has already been carried out, try asking Claude Code to “Undo the recent change.” For projects using Git, you can also restore files from the change history.

Q5: Claude Code seems to be stuck. What should I do?

A: Press Ctrl + C to interrupt, then restart with the claude command. If it stopped in the middle of a long process, resetting the history with /clear and trying again sometimes helps. You can also use claude --continue to resume from where the previous conversation left off.

Q6: Even though I give instructions in my language, it sometimes responds in English.

A: Adding explicit language instructions in your CLAUDE.md, such as “Language: English” and “All responses should be in English,” significantly increases the likelihood of responses in your preferred language. You can also add “Please respond in English” on the spot.

Q7: Can Claude Code connect to the internet and retrieve the latest information?

A: Claude Code communicates with Anthropic’s AI model to operate. Depending on your environment and tool settings, it may be able to fetch web pages. However, for real-time information (today’s weather, the latest news, etc.), we recommend verifying AI responses against official sources rather than relying on them directly.

Q8: Do I have to create a CLAUDE.md file?

A: It is not required. Claude Code works perfectly fine without a CLAUDE.md. However, having one saves you from repeating the same context every time and improves the quality and consistency of outputs. We strongly recommend creating one, especially if you repeatedly request the same type of task.

Q9: Can I use Claude Code differently across multiple projects (folders)?

A: Yes, you can. By placing a separate CLAUDE.md in each folder, you can use Claude Code with different settings per folder. For example:

sales-reports/
  ├── CLAUDE.md    ← Settings for sales reports
  └── ...

marketing-content/
  ├── CLAUDE.md    ← Settings for marketing content
  └── ...

When you launch claude in each folder, the corresponding CLAUDE.md is automatically loaded.

Q10: How do I update Claude Code?

A: Run the following command in your terminal:

npm update -g @anthropic-ai/claude-code

Regular updates let you benefit from new features and bug fixes. You can check your current version with claude --version.

5. Troubleshooting

Here are common issues and their solutions, organized by situation.

5.1 Cannot Install

5.2 Cannot Launch

5.3 Issues During Use

5.4 Windows-Specific Issues

5.5 If Nothing Else Works

Try the following steps in order:

1. Copy the error message When an error appears, copy it exactly as shown. It is fine if it is in English.

2. Ask Claude Code If Claude Code is running, paste the error message and ask, “What is the cause and solution for this error?”

3. Restart the terminal Simply closing and reopening the terminal app sometimes resolves the issue.

4. Restart your computer Many temporary problems are resolved by restarting your computer.

5. Check the official documentation The Claude Code official documentation has the latest information and troubleshooting guides.

6. Contact your IT department For issues related to corporate networks, proxies, or security settings, please consult your IT department.

Quick Reference Card

A one-page summary of the things you use every day. Print it out and keep it handy.

+----------------------------------------------------------+
|            Claude Code Quick Reference                    |
+----------------------------------------------------------+
|                                                          |
|  [Launch & Exit]                                         |
|    Launch:  claude                                       |
|    Exit:    /exit  or  Ctrl+C twice                      |
|    Resume:  claude --continue                            |
|                                                          |
|  [Common Slash Commands]                                 |
|    /help    ... Show help                                |
|    /status  ... Check status                             |
|    /clear   ... Reset conversation                       |
|    /compact ... Compress conversation                    |
|    /cost    ... Check usage costs                        |
|                                                          |
|  [Permission Prompt Responses]                           |
|    y ... Allow    n ... Deny    a ... Always allow        |
|                                                          |
|  [Basic Terminal Commands]                               |
|    pwd      ... Show current location                    |
|    ls       ... List files                               |
|    cd name  ... Move to folder                           |
|    cd ..    ... Go up one level                          |
|    cat name ... Display file contents                    |
|    mkdir    ... Create a folder                          |
|                                                          |
|  [Tips for Writing Instructions]                         |
|    1. Be specific about what you want created            |
|    2. Specify the file format (Markdown, CSV, etc.)      |
|    3. Specify the file name                              |
|    4. If it doesn't work, give additional instructions   |
|                                                          |
+----------------------------------------------------------+

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