Metadata-aware gzip archiver
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arcgzip is an alternative python gzip library, of which focus is on the full support of gzip metadata.

Specifically, this library enables you to ...

  • extract all of the meta information defined in RFC-1952.
  • create an archive with fine-tuned header data.
  • handle multiple files in a single gzip archive.


  • Python 3.2 or later required (Python 2.7 is also supported)

  • Download the source code and run '':

    $ python install

Command-line Usage -l archive.gz         - Show the list of contents. -a archive.gz targets - Add target files to the archive. -c archive.gz targets - Create a new archive from target files. -d archive.gz targets - Extract files from the archive,

Create/Append Options

--ascii        - Set ASCII text flag.
--crc16        - Add crc16 checksum field to the header.
--comment [S]  - Add file comments for the file.
--content [S]  - Write the string to archive (instead of target files)
--encoding [S] - Specify the encoding of the string (with --content)
--exfield [B]  - Set the base64-encoded data to the extra field.
--level [N]    - Compression level to be used (1-fastest/9-slowest)


  • Support stream input.
  • Implement iterator interface on GzipFile class.
  • Add functional tests for command-line options.
  • Improve the output format of 'LIST' mode.


Belows are some thoughts on the design issues of arcgzip.

  • Some user may find it useful if arcgzip provides 'no-strict' mode which skips all the CRC16/CRC32/ISIZE checks.
  • It might be good idea to provide an accommodating interface to 'exfield' assuming anyone actually makes use of the data field.
  • To support stream input, we will need to implement the I/O wrapper that enable seeking (for some extent, at least) by buffering the input bytes. Is there any standard library that can be used to build that feature?
  • Currently arcgzip buffers all the file contents in memory while decompressing. It's awkward, but it has an advantage that extracted file object doesn't mess the original file pointer of GzipFile.
  • Pickling the GzipInfo array effectively serves as an extrenal index file.