2.5 KiB
attrsum is a Go 1.22 command-line utility that adds, updates, verifies, and clears per-file file content checksums stored in extended attributes (xattrs) on macOS (APFS) and Linux, released under the WTFPL v2.
Original release 2025-05-08.
Current version 1.0 (2025-05-08).
Getting Started — Quick Build
# prerequisites: Go 1.22+
git clone https://git.eeqj.de/sneak/attrsum.git
cd attrsum
go build -o attrsum .
Install
go install git.eeqj.de/sneak/attrsum@latest # into GOPATH/bin or $(go env GOBIN)
Semantic Versioning 2.0.0 is used for tags.
Usage
# add checksum & timestamp xattrs to every regular file under DIR
attrsum sum add DIR
# update checksum only when file mtime is newer than stored sumtime
attrsum sum update DIR
# verify checksums, stop on first error
attrsum check DIR
# verify every file, reporting each result, keep going after errors
attrsum -v check --continue DIR
# remove checksum & timestamp xattrs
attrsum clear DIR
| xattr key | meaning |
|---|---|
berlin.sneak.app.attrsum.checksum |
base-58 multihash (sha2-256) |
berlin.sneak.app.attrsum.sumtime |
RFC 3339 timestamp of checksum |
Flags:
-v, --verbose— per-file log output--exclude PATTERN— skip paths matching rsync/Doublestar glob--exclude-dotfiles— skip any path component that starts with.
attrsum never follows symlinks and skips non-regular files (sockets, devices, …).
Why?
Apple APFS and Linux ext3/ext4 store no per-file metadata checksums, so
silent data corruption can pass unnoticed. attrsum keeps a portable,
tamper-evident checksum inside each file’s xattrs, providing integrity
verification that travels with the file itself—no external database
required. Now you can trust a USB stick didn't eat your data.
Contributing
- Author & maintainer: sneak – sneak@sneak.berlin
- Issues / PRs: https://git.eeqj.de/sneak/attrsum/
- Code must pass
go vet,go test ./..., andgo fmt. - No CLA; contributions are under WTFPL v2.
Community & Support
Bug tracker and wiki are in the Gitea repo linked above.
No formal Code of Conduct; be excellent to each other.
License
Everything is permitted. See WTFPL v2.