How to Use rsync on Linux: Commands, Flags, and Examples

What rsync Does

The name rsync stands for remote sync. It can copy files locally between drives or folders, and it can also sync files to another computer over SSH. One of its biggest advantages is efficiency. After the first run, rsync only transfers changed data instead of copying everything again.

This makes it especially useful for:

• Backing up one drive to another
• Keeping folders in sync
• Resuming interrupted transfers
• Copying large amounts of data safely
• Mirroring files to remote servers

Basic rsync Syntax

rsync [options] source destination

Example:

rsync -av /home/user/Documents/ /mnt/backup/Documents/

This copies the contents of the source folder into the destination while preserving important file information.

Important Note About Trailing Slashes

One of the most important things to understand with rsync is the trailing slash.

rsync -av /source/folder /destination/
rsync -av /source/folder/ /destination/

These two commands do not behave the same way:

• /source/folder copies the folder itself into the destination
• /source/folder/ copies the contents of the folder into the destination

Common rsync Flags Explained

-a or --archive

This is one of the most commonly used flags. Archive mode preserves permissions, ownership, timestamps, symbolic links, and recursive copying. It is usually the starting point for backup jobs.

rsync -a source/ destination/

-v or --verbose

Shows what rsync is doing as it runs.

rsync -av source/ destination/

-h or --human-readable

Makes sizes easier to read, such as KB, MB, GB, and TB.

rsync -avh source/ destination/

--progress

Displays progress information during transfers, which is especially useful for large files.

rsync -avh --progress source/ destination/

--partial

Keeps partially transferred files if the copy is interrupted. This helps when resuming large transfers.

rsync -avh --partial source/ destination/

--append-verify

Useful for resuming large files. It appends missing data and verifies correctness.

rsync -avh --append-verify source/ destination/

--delete

Deletes files from the destination if they no longer exist in the source. This makes the destination mirror the source.

rsync -av --delete source/ destination/

-n or --dry-run

Shows what would happen without actually copying or deleting anything. This is one of the safest ways to test an rsync command before running it for real.

rsync -avhn --delete source/ destination/

-z or --compress

Compresses data during transfer. This is mainly useful for network transfers, not local drive-to-drive copies.

rsync -avz user@remote:/path/ /local/path/

-P

This is shorthand for:

--partial --progress

It is very common for large transfers.

rsync -avhP source/ destination/

-r or --recursive

Copies directories recursively. It is included in -a, so you usually do not need it separately when using archive mode.

-u or --update

Skips files that are newer on the destination. Useful when you do not want to overwrite more recent copies.

rsync -avu source/ destination/

-t or --times

Preserves modification times. This is included in -a.

-p or --perms

Preserves file permissions. Also included in -a.

-o and -g

Preserve owner and group. These are included in -a, but ownership preservation may require root privileges.

--info=progress2

Shows overall transfer progress instead of only per-file progress. This is useful for very large jobs with many files.

rsync -avh --info=progress2 source/ destination/

--exclude

Excludes files or directories that match a pattern.

rsync -avh --exclude="*.tmp" --exclude="cache/" source/ destination/

--bwlimit=VALUE

Limits transfer speed. Useful if you want to reduce heat, avoid saturating a connection, or keep the system responsive.

rsync -avh --progress --bwlimit=50M source/ destination/

-e ssh

Tells rsync to use SSH for remote transfers.

rsync -avh -e ssh /local/folder/ user@remote:/backup/folder/

Common rsync Examples

1. Copy a folder to another local drive

rsync -avh /home/user/Documents/ /mnt/backup/Documents/

2. Copy with progress shown

rsync -avhP /mnt/source/ /mnt/destination/

3. Mirror one folder to another

rsync -avh --delete /mnt/source/ /mnt/backup/

4. Test before doing anything

rsync -avhn --delete /mnt/source/ /mnt/backup/

5. Resume a large interrupted copy

rsync -avhP --append-verify /mnt/source/ /mnt/backup/

6. Limit speed to reduce load and heat

rsync -avhP --bwlimit=100M /mnt/source/ /mnt/backup/

7. Exclude unwanted files

rsync -avh --exclude="*.cache" --exclude="lost+found" /mnt/source/ /mnt/backup/

8. Copy to a remote server over SSH

rsync -avh -e ssh /home/user/site/ user@example.com:/var/www/site/

Recommended rsync Commands for Backups

Simple backup command

rsync -avh /source/ /destination/

This is a good default when you want to copy data and preserve metadata.

Backup with progress and resume support

rsync -avhP /source/ /destination/

This is better for large transfers or external drives.

Full mirror backup

rsync -avh --delete /source/ /destination/

This keeps the destination exactly matched to the source.

When to Use rsync Instead of cp

The cp command works fine for simple copies, but rsync is usually better when:

• You want to resume interrupted transfers
• You want progress information
• You need to preserve metadata
• You only want to copy changed files
• You want to mirror one folder to another
• You are copying over a network

Common Mistakes to Avoid

1. Using the wrong trailing slash
   This can copy a folder itself instead of its contents, or the other way around.
2. Using --delete without testing first
   Always consider running a dry run before using delete.
3. Forgetting permissions
   Some files may require sudo if you need ownership and permissions preserved properly.
4. Using compression for local transfers
   Compression usually helps over networks, but can slow local drive-to-drive copies.
5. Assuming rsync means instant transfers
   The first run can still take a long time if you are copying many terabytes of data.

Useful Safe Testing Pattern

A good habit is to first test with a dry run:

rsync -avhn --delete /source/ /destination/

If the output looks correct, then run the real command:

rsync -avh --delete /source/ /destination/

Using rsync for External Drives and Large Transfers (Multi-TB)

When working with large drives like 10TB, 12TB, or 18TB disks, rsync behaves a little differently in practice. Transfers can run for hours or even days, and reliability becomes more important than speed.

Recommended Command for Large Drive Transfers

rsync -avhP --partial --append-verify /mnt/source/ /mnt/destination/

This command is ideal for large datasets because:

• -a preserves all file metadata
• -v shows activity
• -h makes sizes readable
• -P shows progress and keeps partial files
• --append-verify safely resumes interrupted files

Resuming After Interruptions

If a drive disconnects or the system shuts down, simply run the same command again:

rsync -avhP --append-verify /mnt/source/ /mnt/destination/

rsync will skip completed files and continue where it left off.

Prevent Overheating and System Slowdowns

Large transfers can push drives to their limits. If you notice heat issues or instability, limit the transfer speed:

rsync -avhP --bwlimit=100M /mnt/source/ /mnt/destination/

This reduces stress on the drive and can prevent disconnects.

Handling Problematic Drives (I/O Errors)

If a drive has bad sectors or read errors, rsync may stop or skip files. You can make it more tolerant:

rsync -avhP --ignore-errors /mnt/source/ /mnt/destination/

For severely damaged drives, consider using ddrescue first to clone the disk, then run rsync on the recovered data.

Running a Second Pass to Catch Missed Files

After a large transfer completes, it is a good idea to run rsync again to pick up anything missed:

rsync -avh /mnt/source/ /mnt/destination/

This second pass is usually much faster and ensures everything is fully synced.

Verifying Transfer Size

You can quickly compare sizes between drives:

du -sh /mnt/source
du -sh /mnt/destination

If the sizes are close, your transfer likely completed successfully.

Best Practices for Large Transfers

• Use a fan or cooling for external drives during long transfers
• Avoid USB hubs if possible, connect drives directly
• Run transfers on a stable system (avoid sleep mode)
• Always test with --dry-run before using --delete
• Expect the first transfer to take a long time

Final Thoughts

rsync is one of the most valuable Linux tools for file transfers, backups, and synchronization. Once you understand the core flags like -a, -v, -h, -P, --delete, and --dry-run, you can handle most backup and copy tasks with confidence.

For many Linux users, rsync becomes the go-to command for moving data between drives, creating backup routines, and safely syncing files. Start with simple commands, test with dry runs when needed, and build from there.