ferrosys-cli 0.2.0

Command-line ext2/3/4 formatter, inspector, and extractor built on ferrosys
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# ferrosys-cli

The `ferrosys` command line: create an ext2, ext3, or ext4 filesystem, report on one, and
read one back. It runs in userspace as a single self-contained binary, in safe Rust, over
[`ferrosys`](https://crates.io/crates/ferrosys), and builds on Rust 1.88 or newer.

> **Status:** under active development. The command-line interface is not yet stable.
> Following Cargo's `0.x` semantics, a breaking change bumps the minor version.

```console
$ cargo install ferrosys-cli

$ ferrosys format --size 512M --uuid "$(uuidgen)" --time 1700000000 \
      --from-tar rootfs.tar rootfs.img
$ ferrosys inspect rootfs.img
$ ferrosys extract rootfs.img --to-tar - | tar -tv
$ ferrosys detect rootfs.img
ext4
```

## The four subcommands

- **`format`** writes a filesystem — from a tar archive (`--from-tar`), from a directory
  tree on this machine (`--from-dir`, with `--owner UID:GID` to override the host's
  ownership), or empty. The size, UUID, and timestamps are inputs; the tool reads neither
  the clock nor a random source, so the same inputs write the same image every time. Grow
  reservation, block size, inode count, reserved percentage, volume label, journal size,
  feature set, and directory hash are all options. `--dry-run` reports the geometry
  without opening the destination, and `--atomic` publishes the image only once it is
  whole. Walking a tree records Linux inode metadata and Linux extended attributes, so
  `--from-dir` is carried out on Linux; `--from-tar` reads an archive on any platform the
  binary builds for.
- **`inspect`** reports what a filesystem says about itself and whether it is sound —
  as a table a person reads, as JSON, or as SARIF for a pipeline that ingests findings.
  A full scan walks every group descriptor, bitmap, inode, and extent tree, collecting
  each deviation as a typed anomaly; `--fail-on` sets the severity at which the run
  fails.
- **`extract`** reads the contents back out: as a tar archive, as one file's bytes, as
  one path's full metadata (`--stat`, extended attributes and decoded ACLs included), or
  as a listing.
- **`detect`** says which filesystem an image holds — one word, at an offset if asked.

## Streams and exit codes

The standard output carries exactly one artifact per run — a report, a listing, a tar
stream, or one file's bytes. Everything else goes to the standard error, so a pipe never
receives a summary line where an artifact should have been.

The exit codes mirror `e2fsck`'s, and the line between 4 and 8 is whether an opinion
about a filesystem could be formed at all:

| Code | Meaning                                                                    |
| ---- | -------------------------------------------------------------------------- |
| `0`  | The command did what it was asked, and any filesystem it read is sound.     |
| `4`  | A filesystem was read, and it is bad.                                       |
| `8`  | The command could not be carried out: the host got in the way, or the bytes are not an ext filesystem at all. |
| `16` | The command line could not be understood.                                   |

## Documentation

The guide's [command-line chapter](https://gregordinary.github.io/ferrosys/cli.html) covers
every subcommand and option.

## License

Licensed under either of Apache License, Version 2.0 or the MIT license, at your option.