Can You Restore Your Linux Backup? Test It in 6 Steps

Use the backup you already created

This lesson continues the seven-step archive tutorial. You need its training directory, unchanged source files, files.tar.gz and files.tar.gz.sha256. Use Bash with GNU tar, gzip, GNU Coreutils, GNU diffutils and find. Work as your ordinary user, without sudo.

Run every step in the same terminal. If a check fails, stop before extracting or recording a pass. To locate the directory from Lesson 02:

find "$HOME" -maxdepth 1 -type d -name 'sa-backup-lab.*' -print
read -r -p 'Paste the full lab directory path: ' backup_lab

Paste the actual path without surrounding quotes. If several directories appear, choose the one that contains your intended archive. Check the tools and required paths:

command -v tar gzip sha256sum mktemp diff find
tar --version
diff --version
test -d "$backup_lab/source" &&
test -f "$backup_lab/archives/files.tar.gz" &&
test -f "$backup_lab/archives/files.tar.gz.sha256" &&
printf 'Required lab paths found.\n'

Confirm that every tool has a path, tar and diff identify their GNU implementations, and the final message appears. Finding the paths does not yet verify their contents.

Verify the archive before opening it

(
  cd "$backup_lab/archives" &&
  sha256sum --check files.tar.gz.sha256
)

files.tar.gz: OK

Continue only if the check succeeds. A failure means the file does not match the recorded checksum, or the check could not be completed. Read the message and investigate; generating a new checksum would hide the original comparison.

tar --list --gzip --file="$backup_lab/archives/files.tar.gz"

Expect the three training files: ./readme.txt, ./notes/todo.txt and ./.demo-settings, plus their directory entries.

Give this restore its own empty directory

Create a unique destination alongside your source and archive directories. Each new attempt should get a fresh directory, so leftover files cannot disguise an incomplete extraction.

restore_dir=$(mktemp -d "$backup_lab/restore.XXXXXX")
printf 'Restore destination: %s\n' "$restore_dir"

Confirm that the command succeeded and printed the new path. Keep this terminal open: restore_dir points to the destination used below.

Extract into the directory you just made

tar --extract --gzip \
  --file="$backup_lab/archives/files.tar.gz" \
  --directory="$restore_dir" \
  --no-same-owner --no-same-permissions \
  && printf 'Extraction completed.\n'

--directory sets the extraction destination. --no-same-owner avoids trying to recreate the archive’s recorded ownership, while --no-same-permissions lets your current umask limit restored permissions. Those choices suit these ordinary training files.

Wait for successful completion before comparing. An extraction that stops partway through can leave files behind without restoring everything.

find "$restore_dir" -type f -print
cat "$restore_dir/.demo-settings"

DEMO_MODE=yes

The find output should contain all three training file paths. The cat output above checks the hidden file’s readable contents.

Look for differences, including missing files

For this small directory of regular files, a recursive comparison checks corresponding file contents and reports entries found only on one side. Passing directories directly includes hidden entries.

if diff -rq -- "$backup_lab/source" "$restore_dir"; then
  restore_compare_status=0
else
  restore_compare_status=$?
fi
printf 'Comparison exit status: %s\n' "$restore_compare_status"

For unchanged Lesson 02 files, expect no difference messages and an exit status of 0.

Keep the result specific

Inspect the ownership and permissions of a representative file on both sides:

ls -l "$backup_lab/source/readme.txt" "$restore_dir/readme.txt"

A restrictive umask may produce different permission bits after extraction. Decide whether that matches the recovery requirements; matching text does not settle the question. Real services may need a particular account, group or additional metadata.

After the earlier checks succeed, write a small record of the file-content comparison. The block refuses to record a pass unless Step 05 returned zero:

if [ "${restore_compare_status:-2}" -eq 0 ]; then
  printf 'Checked at: %s\nArchive: %s\nRestored to: %s\nFile-content comparison: PASS\n' \
    "$(date -u '+%Y-%m-%dT%H:%M:%SZ')" \
    "$backup_lab/archives/files.tar.gz" \
    "$restore_dir" > "$restore_dir.restore-check.txt"
  printf 'Record: %s\n' "$restore_dir.restore-check.txt"
else
  printf 'No pass recorded. Resolve the comparison result first.\n'
fi

The record sits outside the restored directory, so it does not add a file to the tree you compared. Add your metadata observations, how long the rehearsal took and any steps that needed clarification.

What this rehearsal proves

Keep the archive, checksum and test record until you have reviewed the result. For a real application, the next rehearsal belongs in an isolated environment with its dependencies available and production integrations disabled.