RsyncProject/rsync
Rsync
rsync is a file synchronization and transfer tool that copies data between local and remote systems by sending only the differences between source and destination files. It computes matching blocks using checksums, so only the unmatched portions of files are transmitted, making repeated synchronizations much faster than full copies. The tool preserves file metadata such as ownership, permissions, and modification times during transfers.
rsync supports multiple transfer methods, including direct connections through a dedicated daemon mode or via remote shells like SSH. It can mirror directory trees across systems, optionally deleting files on the receiving side that no longer exist at the source. The tool also handles incremental backups, locally mounted filesystem synchronization, and file transfers over low-bandwidth links. For performance, rsync can accelerate checksum computation using xxHash or OpenSSL, and offers lz4 or zstd compression options to reduce CPU overhead during transfers.
The project provides source code downloads, package manager installations, and a maintained Ubuntu PPA for stable or development snapshots. Documentation is available through HTML versions of man pages, FAQs, tutorials, and technical reports. Community interaction occurs via mailing lists for discussions, announcements, and source-code change notifications, with web-based archives for browsing past messages.
Features
- File Transfer and Sync - Transfers only the differences between source and destination files, minimizing data sent over the network.
- Daemon File Servers - Runs a background process that listens on a network socket to provide anonymous or authenticated file access to remote clients.
- Directory Structure Mirroring - Transfers only the differences between source and destination directories, keeping them identical by deleting extraneous files on the receiving side.
- SSH Directory Syncs - Transfers files between local and remote systems using SSH or a dedicated daemon, sending only the differences to minimize bandwidth.
- Remote File Transfers - Establishes a connection through a remote shell like SSH, treating the link as a pipe for file transfer.
- Low-Bandwidth Mesh File Transfers - Transfers only the differing parts of a file between two machines, minimizing data sent over slow connections.
- File System Incremental Backups - Copies changed files from a local disk to a backup location, preserving permissions and excluding unnecessary items.
- Incremental - Transfers only the changed portions of files between systems, making repeated synchronizations much faster than full copies.
- File Transfer Metadata Preservations - Retains ownership, permissions, modification times, and optionally checksums during file transfers.
- SSH Transport Integrations - Compiles and configures SSH under gnuwin32 to serve as the secure transport layer for rsync transfers.
- Checksum-Based Block Matching - Identifies matching blocks between source and destination using checksums, so only unmatched parts are transmitted.
- Incremental File Reconstructions - Rebuilds the target file by copying matching blocks from the existing file and applying only the changed data.
- Daemon File Synchronizations - Connects directly to a network socket on a remote rsync daemon for file synchronization.
- OpenSSL-Accelerated Checksums - Uses OpenSSL's hardware-accelerated routines to compute MD4 and MD5 checksums faster.
- Local Directory Synchronizations - Performs file sync between two directories on the same machine using forked processes communicating over pipes.
- Pattern-Based Remote File Selections - Uses a shell command on the remote host to generate a list of files matching a pattern, then transfers only those files.
- LZ4 Compression - Applies lz4 compression during transfers to minimize CPU overhead at the cost of compression ratio.
- Zstandard Compression - Applies zstd compression during transfers to reduce CPU usage compared to the default algorithm.
- Release Signature Verifiers - Verifies the authenticity of release files using GPG signing keys from public key servers.
- xxHash Accelerated Checksums - Uses the xxHash library to compute checksums faster, speeding up block matching in large files.
