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NOQTIS

noqtis-chunk(1)

noqtis-chunk — record the chunk digests of a large file, and check a piece of it

noqtis chunk pin [--size bytes] dir file ...

noqtis chunk check [--at offset] [-j | --json] dir file [piece]

pin reads each file in dir once and records in the data record (chunks, noqtis-data(5)) the SHA-256 of each run of --size bytes (default 1048576; 1024 to 1073741824), the last run short. The file is not split. Seal the folder afterwards: the seal covers the digests through the record.

check checks file, or piece, a part of it whose first byte is byte --at of the file (a multiple of the chunk size; default 0), against the recorded digests: each whole chunk it holds, and a short last one when it ends where the file does. Only that is read, so a range fetched alone, or the part of a file that survived, can be checked without the rest. A short run at the end of a piece that is not the file's end is not checked, and a row says so.

To trust the digests without the file, check the record's seal alone: ‘noqtis check --only noqtis.data.json’. noqtis-data(1) check checks each file whole against its chunks.

0
Recorded; or every chunk read matches.
1
A chunk differs, the piece runs past the file, or it holds no whole chunk.
2
A usage or file error, or no chunks recorded for file.

$ noqtis chunk pin --size 4194304 results data/big.parquet
$ noqtis seal -k me results
$ curl -r 8388608-16777215 -o part https://example.org/big.parquet
$ noqtis check -p me.pub --only noqtis.data.json results
$ noqtis chunk check --at 8388608 results data/big.parquet part

noqtis-check(1), noqtis-data(1), nqdchunk(3), noqtis-data(5)