rsync

Sync a local directory to another location

$ rsync -av [source/] [destination/]

$ rsync -av [source/] [user]@[host]:[destination/]

$ rsync -av [user]@[host]:[source/] [destination/]

$ rsync -av --delete [source/] [destination/]

$ rsync -avn [source/] [destination/]

$ rsync -av --progress [source/] [destination/]

$ rsync -av --exclude="*.log" [source/] [destination/]

$ rsync -avz [source/] [user]@[host]:[destination/]

rsync [options] source... destination

rsync is a fast, versatile file copying tool that synchronizes files between locations. It uses a delta-transfer algorithm, transmitting only differences between source and destination, making it efficient for incremental backups and mirrors.
The trailing slash on source paths is significant: source/ copies contents, while source copies the directory itself. This is a common source of confusion.
Rsync can operate locally or over a network using SSH (default), RSH, or its own daemon protocol. For remote transfers, format is user@host:path or rsync://user@host/path for daemon mode.
The -a (archive) flag is commonly used as it preserves permissions, timestamps, symbolic links, and recurses into directories—suitable for most backup scenarios.

-a, --archive

Archive mode; equals -rlptgoD (recursive, links, perms, times, group, owner, devices)

Increase verbosity

Compress file data during transfer

Show what would be transferred without making changes

Delete files in destination that don't exist in source

Exclude files matching pattern

Include files matching pattern (after excludes)

Show progress during transfer

Same as --partial --progress

Keep partially transferred files

Recurse into directories

Skip files newer on destination

Compare by checksum, not mod-time & size

Specify remote shell to use (e.g., -e ssh)

Limit bandwidth in KB/s

Output numbers in human-readable format

Trailing slash matters: rsync -a source/ dest/ copies contents; rsync -a source dest/ copies the directory into dest.
--delete removes files from destination. Always use -n (dry run) first to verify what will be deleted.
Symbolic links are copied as symlinks by default. Use -L to follow symlinks and copy their targets.
For large transfers over unreliable connections, use -P (--partial --progress) to enable resumption of interrupted transfers.

Rsync was created by Andrew Tridgell and Paul Mackerras in 1996. The name comes from "remote sync." The delta-transfer algorithm was based on Tridgell's PhD thesis. Rsync became a fundamental tool for Unix system administration, backups, and mirroring.

scp(1), cp(1), rclone(1), tar(1)