Recap: Lock It Down
Chapter 7 taught you the security layer of the station's file system:
| Command | Purpose |
|---|---|
ls -l | View permissions and ownership |
chmod u+x | Add/remove permissions (symbolic) |
chmod 755 | Set all permissions at once (numeric) |
whoami | Show your username |
id | Show uid, gid, and groups |
Remember the permission triad: user → group → others, each with r, w, x.
Numeric: r=4, w=2, x=1. Add them up per group.
Mission: Lockdown Protocol
A security breach was detected on deck 3. The captain has issued a lockdown order: three files in your directory need their permissions tightened immediately.
launch_codes.txt: Top secret. Only the owner may read and write it; the group and others get no access at all.status_report.sh: Operational script. The owner gets full access, the group can read and execute it, and others get nothing.public_bulletin.txt: Station-wide bulletin. Everyone can read it, but only the owner can write.
Set each file's permissions accordingly, then confirm the result.
Expected result
The three files end up as -rw------- for launch_codes.txt, -rwxr-x--- for status_report.sh, and -rw-r--r-- for public_bulletin.txt. Lockdown complete.