backdown

backdown dedup

Tidy an archive: identical files in FOLDER share their storage, as hardlinks or clones. Both files are re-read first; every link is journaled. Without --go, only shows what would happen.

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backdown dedup [OPTIONS] <FOLDER>

Arguments

<FOLDER>
The folder to tidy, usually the archive. Only files inside it, on the same drive, are linked.

Options

--link <LINK>
hard: one file with several names (any filesystem; editing one edits them all). clone: separate files sharing blocks until one changes (btrfs, XFS, APFS). Default: hard.
--min-size <MIN_SIZE>
Leave smaller files alone (e.g. 4K, 1M). Default: 4K.
--dry-run
Only show what would happen (the default).
--go
Link them.
--json
Print it as JSON, for scripts.

Also takes the global options --db and --local.

Good to know

Only files the index has hashed and that are identical, on the same drive, inside FOLDER; files whose permissions, owner or extended attributes differ (and, for hardlinks, their modification time), or that also have names outside FOLDER, are left alone. Clones need btrfs, XFS or APFS. Each pair is read again first; every link is journaled, and running it again carries on. It refuses the running system, whole home folders and BackDown's index, and isn't available on Windows yet. Index the drive afterwards (the daemon does). Exits 2 when some files failed.

Examples

# what would be linked (changes nothing)
backdown dedup /media/archive/Archive
# on btrfs, XFS or APFS: separate files that share their blocks
backdown dedup /media/archive/Archive --link clone --go

See also

Last updated · What's released, and what's next