https://github.com/xyb/chunksum

Print FastCDC rolling hash chunks and checksums.
https://github.com/xyb/chunksum

checksum chunking content-defined-chunking dedup deduplication fastcdc rolling-hash

Last synced: about 1 month ago
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Print FastCDC rolling hash chunks and checksums.

• Host: GitHub
• URL: https://github.com/xyb/chunksum
• Owner: xyb
• License: mit
• Created: 2022-11-05T12:54:23.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2022-11-27T12:49:05.000Z (almost 2 years ago)
• Last Synced: 2024-08-09T04:38:10.401Z (3 months ago)
• Topics: checksum, chunking, content-defined-chunking, dedup, deduplication, fastcdc, rolling-hash
• Language: Python
• Homepage:
• Size: 50.8 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# chunksum

Print FastCDC rolling hash chunks and checksums.

[![test](https://github.com/xyb/chunksum/actions/workflows/test.yml/badge.svg)](https://github.com/xyb/chunksum/actions/workflows/test.yml)

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```

usage: chunksum [-h] [-n ALG_NAME] [-f CHUNKSUMS_FILE] [-i INCR_FILE] [-m]

                [path ...]

Print FastCDC rolling hash chunks and checksums.

positional arguments:

  path                  path to compute chunksums

optional arguments:

  -h, --help            show this help message and exit

  -n ALG_NAME, --alg-name ALG_NAME

                        chunksum algorithm name.

  -f CHUNKSUMS_FILE, --chunksums-file CHUNKSUMS_FILE

                        chunksum file path, `-' for standard output.

  -i INCR_FILE, --incr-file INCR_FILE

                        incremental updates file path

  -m, --multi-process   same number of multi-processes as cpu

alg-name:

  Format "fc[k|m|g][0-9][sha2|blake2b|blake2s][32]".

  For example, "fck4sha2", means using FastCDC("fc") with an

  average chunk size of 2**8=256KB("k8") and using sha256("sha2")

  to calculate the checksum.

  "fcm4blake2b32" means using FastCDC with an average chunk size

  of 2**4=16MB("m4") and using "blake2b" to calculate and output

  a checksum of length "32" bytes(save storage).

  For large files, you may using large chunk size, such as "m4",

  to reduce the number of chunks.

  (default: fck4sha2)

chunksums-file and incr-file:

  You can specify the previous chunksums file if you want to

  resume a previous check, or if you want to find the incremental

  updates (new files) of the directory.

Examples:

  $ chunksum /etc > ~/etc.chunksums

  $ chunksum -n fcm4blake2b32 -m ~/Videos

  $ chunksum -n fcm4blake2b32 -f ~/Videos/chunksums ~/Videos

  $ chunksum -n fcm4blake2b32 -f ~/chunksums -i ~/chunksums.incr ~/Videos

```