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Hosting Operations

Dry run / preview

Preview Backup Drift with rsync

You need to see source-to-backup drift without modifying the backup.

Command

rsync -ain --delete source/ backup/

Before you run this

System impact: Preview only. Still verify source and destination paths before running the real command.

When not to use it: Do not remove -n or keep --delete in a live sync until you understand every itemized change.

Expected output

Itemized rsync changes that would update, create, or delete files.

System impact

Dry run / preview. Nothing changes while -n is present; rsync only reports what would update, create, or delete.

When to use it

Use before syncing backups, especially when the real command may delete stale files.

When not to use it

Do not remove -n or keep --delete in a live sync until you understand every itemized change.

Recovery / rollback

No undo needed for the dry run. If you later remove -n, take a backup or snapshot first.

Watch this command run

Command transcript

This sanitized transcript shows the commands and output shape without exposing host details.

demo@lab:~$

$ find source backup -type f | sort

backup/.snapshot
backup/app/config.yml
backup/content/index.md
backup/old-report.csv
backup/tmp/empty.cache
source/app/config.yml
source/assets/logo.svg
source/content/about.md
source/content/index.md

$ rsync -ain --delete source/ backup/

*deleting   tmp/empty.cache
*deleting   tmp/
*deleting   old-report.csv
*deleting   .snapshot
cd+++++++++ assets/
>f+++++++++ assets/logo.svg
>f+++++++++ content/about.md
>f.st...... content/index.md
View commands shown

These are the commands shown in the sanitized transcript.

Commands shown

  1. find source backup -type f | sort
  2. rsync -ain --delete source/ backup/

next steps

Related commands

Hosting Operations Can be slow

Compare Source and Backup File Lists

A backup can be missing files and still look plausible at a glance.

comm -3 <(find source -type f | sed 's#^source/##' | sort) <(find backup -type f | sed 's#^backup/##' | sort)
Hosting Operations Can be slow

Find Files Newer Than a Backup Snapshot

Files newer than the last snapshot are the ones most likely missing from it.

find source -type f -newer backup/.snapshot -print | sort
Dangerous Commands Dry run

Preview What Rsync Would Delete

`rsync --delete` is useful. It is also how people erase the wrong side.

rsync -avhn --delete ./source/ ./backup/ | grep '^deleting'
Hosting Operations Can be slow

Create a SHA256 Checksum Manifest

A file list says what exists; checksums say whether bytes match.

sha256sum source/app/config.yml source/content/index.md source/content/about.md source/assets/logo.svg
Study mapping

Use this as independent command practice: read the notes, predict the output, then compare it with the example before using a real shell.

  • lpic1:103-gnu-unix-commands
  • lpic1:104-filesystems-permissions-fhs
  • lfcs:operations-deployment
  • lfcs:services-logs
  • lfcs:storage
  • risk:dry-run

Useful for

  • LPIC-1 style command-line practice
  • LFCS style performance tasks
  • Linux+ style troubleshooting review

Independent study support only. No affiliation, endorsement, exam dumps, or real exam questions.