Files and paths · Lesson 33 of 36 · 8 minutes

Restore copy verification

Copy a restore candidate and compare it with its source.

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learner@clairos:~ $

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Your objectives

Hints are always available. Wrong turns never cost XP.

1
Copy the restore candidate
Run cp restore/index.html lab/restore-candidate.html.
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 restore/index.html lab/restore-candidate.html
```
Remember: Confirm the destination before replacing a file. This lab supports file copies, not every cp option.
2
Compare source and copy
Run diff restore/index.html lab/restore-candidate.html.
Hint & worked example
Compare two text files; a difference is a meaningful nonzero status, not necessarily an execution error.
Inspect the differences. diff exits 1 when files differ and 0 when they match.
```
diff restore/index.html lab/restore-candidate.html
```
Remember: Status 1 means differences for diff; shell status must be interpreted in command context.
3
Hash the copy
Run sha256sum lab/restore-candidate.html.
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 lab/restore-candidate.html
```
Remember: A checksum detects changes only relative to a trusted expected digest.

Understand the pattern

Verifying a copied restore candidate helps operators explain what they know before they change anything.

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.
diff: Compare two text files; a difference is a meaningful nonzero status, not necessarily an execution error.
Status 1 means differences for diff; shell status must be interpreted in command context.
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 restore/index.html lab/restore-candidate.html

(no output; exit 0)

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

$ diff restore/index.html lab/restore-candidate.html

(no output; exit 0)

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

$ sha256sum lab/restore-candidate.html

461e71705c1a1643f91a286005d2017f902347ac41c738e60461bf7a700cf741  /home/learner/lab/restore-candidate.html

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 “Restore copy verification”, which interpretation is safe?A successful first check guarantees that every dependent service is healthy.Status 1 means differences for diff; shell status must be interpreted in command context.A command appearing in history proves it completed successfully.

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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