Files and paths · Lesson 25 of 36 · 8 minutes

Checksum compare

Hash source and restored files to confirm they match.

Open the lab Course map

Mastery 0/3Run itExplain itApply it

learner@clairos:~ $

↑ history · Tab complete · Ctrl+C cancel · Esc, Tab to leaveExit 0

Your objectives

Hints are always available. Wrong turns never cost XP.

1
Copy README into restore
Run cp README.txt restore/README.txt.
Hint & worked example
Copy a file to a new location, leaving the original in place.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
cp README.txt restore/README.txt
```
Remember: Confirm the destination before replacing a file. This lab supports file copies, not every cp option.
2
Hash source
Run sha256sum README.txt.
Hint & worked example
Compare content digests to detect byte changes, not to establish who authored the file.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
sha256sum README.txt
```
Remember: A checksum detects changes only relative to a trusted expected digest.
3
Hash restore copy
Run sha256sum restore/README.txt.
Hint & worked example
Compare content digests to detect byte changes, not to establish who authored the file.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
sha256sum restore/README.txt
```
Remember: A checksum detects changes only relative to a trusted expected digest.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

cp: Copy a file to a new location, leaving the original in place.
Confirm the destination before replacing a file. This lab supports file copies, not every cp option.
sha256sum: Compare content digests to detect byte changes, not to establish who authored the file.
A checksum detects changes only relative to a trusted expected digest.

Worked example and expected result

$ cp README.txt restore/README.txt

(no output; exit 0)

Exit status: 0. The command completed successfully in the training fixture.

$ sha256sum README.txt

a76968d5df26cfd59ecd7d080f8283d65e91ec7366d233b4b98233877aa154c6  /home/learner/README.txt

Exit status: 0. The command completed successfully in the training fixture.

$ sha256sum restore/README.txt

a76968d5df26cfd59ecd7d080f8283d65e91ec7366d233b4b98233877aa154c6  /home/learner/restore/README.txt

Exit status: 0. The command completed successfully in the training fixture.

Try a variation

Repeat this workflow in the sandbox with a different scratch filename. Keep the system fixtures unchanged and compare the observed output with your expectation before moving on.

Explain it

In “Checksum compare”, which interpretation is safe?A command appearing in history proves it completed successfully.A successful first check guarantees that every dependent service is healthy.A checksum detects changes only relative to a trusted expected digest.

Apply it elsewhere

Before adapting the sha256sum workflow from “Checksum compare” to another server, what should you do?Skip output inspection whenever the command is familiar.Confirm the current directory, target identity, permissions, and the installed command behavior first.Paste the training paths unchanged into production.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: Symlink inventory Try an incident drill

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