rsync

Overview

The rsync command is a fast and versatile file synchronization tool that efficiently transfers and synchronizes files between locations, locally or over a network.

Syntax

rsync [options] source destination
rsync [options] source [source...] destination

Common Options

Option Description
-a Archive mode (preserves permissions, times, etc.)
-v Verbose output
-r Recursive
-u Update (skip newer files)
-n Dry run (show what would be done)
-z Compress during transfer
-P Show progress and keep partial files
--delete Delete files not in source
--exclude=pattern Exclude files matching pattern
--include=pattern Include files matching pattern
-e ssh Use SSH for remote transfers

Archive Mode Components

The -a flag includes: - -r (recursive) - -l (copy symlinks as symlinks) - -p (preserve permissions) - -t (preserve modification times) - -g (preserve group) - -o (preserve owner) - -D (preserve device files and special files)

Key Use Cases

  1. Backup files and directories
  2. Synchronize directories
  3. Mirror websites
  4. Transfer files over network
  5. Incremental backups

Examples with Explanations

Example 1: Basic Local Sync

rsync -av source/ destination/

Synchronizes source directory to destination with archive mode

Example 2: Remote Sync via SSH

rsync -avz -e ssh local/ user@server:/remote/path/

Syncs local directory to remote server with compression

Example 3: Dry Run

rsync -avn --delete source/ destination/

Shows what would be synchronized without making changes

Remote Synchronization

  1. Push to remote:

    rsync -av local/ user@host:/remote/

  2. Pull from remote:

    rsync -av user@host:/remote/ local/

  3. Between remote hosts:

    rsync -av host1:/path/ host2:/path/

Advanced Options

Option Description
--bwlimit=rate Limit bandwidth
--timeout=seconds Set timeout
--partial Keep partial files
--inplace Update files in place
--backup Make backups
--backup-dir=dir Backup directory
--log-file=file Log to file
--stats Show transfer statistics

Common Usage Patterns

  1. Incremental backup:

    rsync -av --delete /home/user/ /backup/user/

  2. Exclude patterns:

    rsync -av --exclude='*.tmp' --exclude='cache/' source/ dest/

  3. Bandwidth limited transfer:

    rsync -av --bwlimit=1000 large_files/ remote:/backup/

Include/Exclude Patterns

  1. Exclude temporary files:

    rsync -av --exclude='*.tmp' --exclude='*.log' source/ dest/

  2. Include only specific types:

    rsync -av --include='*.txt' --exclude='*' source/ dest/

  3. Complex patterns:

    rsync -av --exclude-from=exclude.txt source/ dest/

Performance Analysis

  • Delta-sync algorithm (only transfers differences)
  • Compression reduces network usage
  • Efficient for large files with small changes
  • Minimal memory usage
  • Good for slow connections

Backup Strategies

  1. Daily incremental:

    rsync -av --delete --backup --backup-dir=../backup-$(date +%Y%m%d) source/ dest/

  2. Snapshot backups:

    rsync -av --link-dest=../previous source/ current/

  3. Rotating backups:

    rsync -av --delete source/ backup/current/

Additional Resources

Best Practices

  1. Always test with dry run first
  2. Use archive mode for complete sync
  3. Implement proper exclude patterns
  4. Monitor transfer progress
  5. Verify sync completion

Security Considerations

  1. Use SSH for remote transfers
  2. Verify host keys
  3. Use key-based authentication
  4. Limit rsync access with restricted shells
  5. Monitor transfer logs

Troubleshooting

  1. Permission denied errors
  2. Network connectivity issues
  3. Disk space problems
  4. SSH authentication failures
  5. Pattern matching issues

Integration Examples

  1. With cron for automated backups:

    0 2 * * * rsync -av --delete /home/ /backup/

  2. With find for selective sync:

    find source/ -name "*.txt" -print0 | rsync -av --files-from=- --from0 source/ dest/

  3. Monitoring script:

    rsync -av --stats source/ dest/ | tee sync.log

Common Patterns

  1. Website deployment:

    rsync -avz --delete local_site/ user@server:/var/www/html/

  2. Database backup sync:

    rsync -av --compress-level=9 db_backups/ remote:/backups/db/

  3. Media file sync:

    rsync -av --progress --partial media/ backup:/media/