sudo = POWER!! (managing users in Linux) // Linux for Hackers // EP4

User management is the foundation for both legitimate Linux administration and practical hacking: it determines who can log in, what they can access, and how far they can go when permissions escalate. The lesson starts by identifying the current account with `whoami`, then shows how Linux stores account data in `/etc/passwd` and password hashes in `/etc/shadow`. A user account entry includes a username, a UID/GID pair, a home directory path, and a default login shell—often `bash` when created with `adduser`.

From there, the core workflow becomes creating, inspecting, and removing accounts—using the “Avengers” as a memory hook. Creating users can be done two ways: `adduser` and `useradd`. `adduser` is interactive and “does more” by prompting for details like passwords and typically setting up a home directory and other defaults. `useradd` is more barebones: it can create the account record, but it may leave out essentials such as a home directory and can result in a different default shell (the transcript shows `sh` instead of `bash`). After creating a user with `useradd`, the password can be set or changed using `passwd`, and the shell can be corrected with `usermod --shell /bin/bash`.

The next escalation step is privilege management—where the “Infinity Gauntlet” metaphor maps directly to `sudo`. `sudo` grants temporary superuser capabilities (root powers) for a single command, which is why it’s safer than logging in as root. The transcript demonstrates switching identities with `su` (requiring the target user’s password) and contrasts that with `sudo` (which relies on authorization rules rather than knowing the target user’s password). A user can be blocked from using `sudo` until they appear in the sudo authorization rules.

Those rules live in the `sudoers` file, edited via `sudo vi /etc/sudoers` (with emphasis on using the correct method to avoid breaking access). The file defines who can run what commands, including group-based permissions. The lesson then creates a new group named `infinity gauntlet`, adds it to `sudoers` with broad command access (`ALL`), and removes the need for a password (`NOPASSWD`). Once `iron man` is added to that group, he can run `sudo` commands and perform high-impact actions.

Finally, the transcript demonstrates destructive account management using `userdel` (removing users like `thor`, `spider-man`, and others) and then “restoring” them by recreating accounts with `useradd`/`useradd`-style flows. The concluding security principle is least privilege: after the threat is neutralized, the group is deleted with `groupdel`, which removes the special sudo access by removing the group itself—preventing anyone from reusing the “gauntlet” permissions later.