sneak
c856ea25be
- Change sum add, sum update, check, and clear to accept 1+ paths - Update README usage examples to show multiple path support - Add TODO section with planned future improvements
110 lines
3.3 KiB
Markdown
110 lines
3.3 KiB
Markdown
[**attrsum**](https://git.eeqj.de/sneak/attrsum/) is a **Go
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1.22** command-line utility that **adds, updates, verifies, and clears per-file
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file content checksums stored in extended attributes (xattrs) on macOS (APFS) and
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Linux**, released under the [WTFPL v2](http://www.wtfpl.net/).
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Original release 2025-05-08.
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Current version 1.0 (2025-05-08).
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---
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## Getting Started — Quick Build
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```bash
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# prerequisites: Go 1.22+
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git clone https://git.eeqj.de/sneak/attrsum.git
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cd attrsum
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go build -o attrsum .
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```
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### Install
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```bash
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go install git.eeqj.de/sneak/attrsum@latest # into GOPATH/bin or $(go env GOBIN)
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```
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Semantic Versioning 2.0.0 is used for tags.
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---
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## Usage
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```bash
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# add checksum & timestamp xattrs to every regular file under one or more paths
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attrsum sum add DIR1 DIR2 file.txt
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# update checksum only when file mtime is newer than stored sumtime
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attrsum sum update DIR1 DIR2
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# verify checksums, stop on first error
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attrsum check DIR1 DIR2
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# verify every file, reporting each result, keep going after errors
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attrsum -v check --continue DIR1 DIR2
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# remove checksum & timestamp xattrs
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attrsum clear DIR1 DIR2
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```
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| xattr key | meaning |
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|---------------------------------------------|--------------------------------|
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| `berlin.sneak.app.attrsum.checksum` | base-58 multihash (sha2-256) |
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| `berlin.sneak.app.attrsum.sumtime` | RFC 3339 timestamp of checksum |
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Flags:
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* `-v, --verbose` — per-file log output
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* `--exclude PATTERN` — skip paths matching rsync/Doublestar glob
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* `--exclude-dotfiles` — skip any path component that starts with `.`
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`attrsum` **never follows symlinks** and skips non-regular files (sockets, devices, …).
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---
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## Why?
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Apple APFS and Linux ext3/ext4 **store no per-file content checksums**, so
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silent data corruption can pass unnoticed. `attrsum` keeps a portable checksum **inside each file’s xattrs**, providing integrity
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verification that travels with the file itself—no external database
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required. Now you can trust a USB stick didn't eat your data.
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---
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## TODO
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Future improvements under consideration:
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- **Quiet mode (`-q`)** — suppress all output except errors
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- **Dry-run mode (`--dry-run`, `-n`)** — show what would be done without making changes
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- **JSON output (`--json`)** — machine-readable output for scripting and integration
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- **Parallel processing (`-j N`)** — use multiple goroutines for faster checksumming on large trees
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- **Progress indicator** — show progress bar or spinner for long-running operations
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- **Summary report** — print statistics on completion (files processed, errors, bytes hashed)
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- **Read paths from stdin (`-`)** — support piping file lists, e.g. `find ... | attrsum sum add -`
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- **Exit code documentation** — formalize and document exit codes for scripting
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---
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## Contributing
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* Author & maintainer: **sneak** – <sneak@sneak.berlin>
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* Issues / PRs: <https://git.eeqj.de/sneak/attrsum/>
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* Code must pass `go vet`, `go test ./...`, and `go fmt`.
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* No CLA; contributions are under WTFPL v2.
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---
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## Community & Support
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Bug tracker and wiki are in the Gitea repo linked above.
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No formal Code of Conduct; be excellent to each other.
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---
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## License
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*Everything is permitted.*
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See [WTFPL v2](http://www.wtfpl.net/txt/copying/).
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