backdown check
Is PATH safe to wipe? Every file needs a SHA-256-identical copy outside PATH (runs hash first). Exits 0 when safe, 2 when files must be copied first.
On this page
backdown check [OPTIONS] <PATH>Arguments
<PATH>- The drive or folder to check. It must be there now (connected and mounted).
Options
--list- List the files that have no copy elsewhere (the largest 20,000).
--json- Print it as JSON, for scripts.
--jobs <JOBS>- Readers per device; 1 suits spinning disks, raise it for SSDs. Default:
1. --retry-errors- Retry files that failed to read last time.
Also takes the global options --db and --local.
Good to know
Exits 0 when every file has a SHA-256-identical copy outside PATH ("SAFE TO WIPE"), and 2 when some files exist nowhere else or couldn't be read ("COPY FIRST"). Copies on drives that aren't connected still count: the verdict is about the index. --list lists the largest 20,000 such files. Empty files don't count against a drive.
Examples
backdown check /media/old-drive
# every file that has no copy, largest first
backdown check /media/old-drive --list
# in a script: 0 = safe to wipe, 2 = copy first
backdown check /media/old-drive && echo "safe to wipe"See also
Last updated · What's released, and what's next