S2 Recap: Files, Editing, Identity

Session: S2

What Changed

You moved from reading files to making them. Your homepage stopped being a starter page and became your page. You set up SSH-key login early, from your own computer.

The important model is source versus output:

• ~/src/pages/ is source.
• ~/public_html/ is generated output.
• build-website rebuilds output from source.

If the output breaks, rebuild it. If the source breaks, slow down and fix the source.

Commands You Met

• touch: create an empty file or update its timestamp.
• mkdir: create a directory.
• rmdir: remove an empty directory.
• cp: copy files.
• mv: move or rename files.
• rm -i: ask before removing a file.
• rm: remove files.
• chmod: change permission modes; here it protects SSH key paths.
• micro: edit text.
• echo: print text.
• >: replace a file with command output.
• >>: append command output to a file.
• ssh-keygen: generate an SSH key pair.
• ssh-copy-id: install your public key on the server.
• Get-Content: preview a local public key in PowerShell without changing it.
• ls -l: inspect ownership, size, permissions, and names.

rm -rf recursively forces removal. You learned what it means, but did not run it in S2.

Mental Model

Paths matter. ~/playground/file.txt and ~/src/pages/index.md are not the same file.

Before changing a file, ask:

1. Where am I?
2. What path am I editing?
3. Is this source or output?
4. Can I rebuild or recreate it if I break it?

Redirection

Use > when you mean “replace this file”.

Use >> when you mean “add to the end of this file”.

If you accidentally use > twice, the first content is gone. That is not a bot bug. That is what you asked the shell to do.

SSH Keys

Your SSH key has two parts:

• Private key: stays on your device. Do not share it.
• Public key: can be copied to the server.

You created the private key on your own computer and protected it with a passphrase.

If a private key is lost or copied, create a replacement and remove the old public key from the server. If you cannot log in, ask the instructor for recovery. Never send a private key.

Live Core

If you attended live and personalized your homepage, you have the core milestone for S2.

• You can copy, rename, move, and remove playground files deliberately.
• You can explain source under ~/src/pages/ versus generated output under ~/public_html/.
• You can reconnect with your key without entering the account password, run whoami, and know why the private key stays private.
• The guide records your successful public-key login automatically.

Optional Reinforcement

Use the S2 quests for file-operation repetition and guide-checked proof. Run guide now for your current session objective. After you complete it, guide now shows your current quest. Submit prompted answers with guide answer <your answer>. Run guide check after practical work. A passing check records your progress. If stuck, read the quest guide and ask in public help so the answer teaches more than one person.

Full Autonomy

Use S2 Self-Study Guide: Files, Editing, Identity for editor keys, SSH key safety, source/output recovery, and exact proof checks.