---
title: rsync — Incremental Synchronization and Backup
date: 2026-10-18
time: 12:00
model: admin
category: programs
author_type: human
summary: A synchronization tool that transfers only changed parts. Most commonly used for server-to-server backup and deployment.
tags: program, File and disk management, rsync
---

**💬 "rsync command"**

rsync transfers **only the differences**. It is a standard tool used for server-to-server backup, migration, and deployment.

Option combinations matter. Use `-a`(preserve attributes), `-v`(verbose output), `-z`(compress during transfer) as defaults.

- **Concept**: a file synchronization tool that transfers only the differences between source and destination.
- **Left argument**: the source path. If it ends with a slash, it copies the **contents**; if not, it copies the **directory itself**.
- **Right argument**: the destination path. For remote destinations, use the `user@host:/path` format.
- **Deletion**: If you use `--delete`, files not in the source are also deleted from the destination.
## Commonly used options

| Option | Description |
| --- | --- |
| -a | Preserves permissions, timestamps, ownership, and other attributes (archive mode) |
| -v | Prints the files being transferred |
| -z | Compresses during transfer (useful for remote transfers) |
| --delete | Removes files from the destination that are not in the source, making it a full mirror |
| -n / --dry-run | Shows what would change without actually doing anything |

## 3 essential command combinations

- `rsync -avz /var/www/html/ deploy@10.0.0.2:/var/www/html/` — incrementally sync the web root to a remote server
- `rsync -avn --delete /data/ /backup/data/` — preview what would be deleted as well (dry-run)
- `rsync -av --exclude '*.log' /srv/app/ /backup/app/` — back up while excluding logs
**💬 "Show me examples of cost (resource) savings with this"**

Here are common situations on live production servers, organized in order.

### Step 1 · Preview (dry-run)

First, check what will be transferred or deleted. You should especially preview --delete.

```
rsync -avn --delete /srv/app/ /backup/app/
```

### Step 2 · Actual synchronization

If there are no problems, run it without -n.

```
rsync -av --delete /srv/app/ /backup/app/
```

### Step 3 · Verification

Compare file counts, sizes, and representative files.

```
rsync -avn --delete /srv/app/ /backup/app/ | tail -3
```

## How it is used in practice

### 1. Server migration

**Situation** — You need to move /srv/app from the old server to the new server exactly as it is.

```
rsync -avz --exclude 'cache/' /srv/app/ root@10.0.0.9:/srv/app/
```

**Result** — Even for large data, only the changes are transferred, greatly reducing migration time.

**Point** — Run it once before the migration, then run it once more at the time of the service cutover to minimize downtime.

### 2. Log archive backup

**Situation** — You need to move last month's logs to backup storage for retention.

```
rsync -av --remove-source-files /var/log/nginx/2026-09-* /backup/logs/
```

**Result** — After transfer is complete, the source files are deleted, freeing up local disk space.

**Point** — Only use --remove-source-files after verification. It is essential to confirm success so that the source remains if the transfer fails.

## Important notes

- The presence or absence of a trailing slash on the source path completely changes the result. Distinguish between wanting the directory itself and wanting only its contents.
- --delete deletes files from the destination. Always preview with -n first.
- Syncing live DB files can break consistency. Dump the database first and then transfer it.
- Use caution when adding --remove-source-files to automation, because it risks data loss if the transfer fails.
## Actual execution screen

This shows only what would be transferred or deleted in a dry-run (no actual changes were made).

![rsync command execution result: dry-run incremental transfer list](https://games.aidebatehub.com/assets/rsync-demo.png)

Live production server

---
Source (HTML): https://games.aidebatehub.com/programs/linux/filesystem/rsync.html
This file is an auto-generated Markdown twin of the DevHub document.