# Knowledge Check: Users and Permissions Foundations

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**1. A colleague says "permission denied" and fixes it with `chmod 777`. What's wrong with
that fix?**

*Answer:* `777` grants read, write, AND execute to the owner, group, AND everyone else — almost
always far more access than the actual problem required. It "fixes" the symptom while violating
least privilege, usually granting write access nobody asked for.

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**2. What does the permission `644` actually mean, broken down?**

*Answer:* Owner: read+write (4+2=6). Group: read-only (4). Other: read-only (4). Nobody but the
owner can modify the file; everyone can read it.

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**3. Why does `sudo <command>` exist instead of just logging in as root permanently?**

*Answer:* It grants elevated privilege only for the one command that needs it, minimizing the
time spent with full access — reducing the chance a mistake (or a compromised session) causes
serious, wide damage.

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**4. State the least-privilege principle in your own words.**

*Answer:* Grant exactly the access something needs to do its job, and nothing more.

## Instructor Notes

**Facilitation:** Question 1 is worth discussing as a group — most students have seen `chmod
777` somewhere online as "the fix," and unlearning that habit early matters.

**Approximate timing:** 5 minutes.