compression_tool
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COMPRESSION_TOOL(1) COMPRESSION_TOOL(1)
NAME
compression_tool - encode/decode files using the Compression library
SYNOPSIS
compression_tool -encode | -decode [-a algorithm] [-A algorithm]
[-i input_file] [-o output_file] [-v] [-h]
DESCRIPTION
compression_tool encodes (compresses), or decodes (uncompresses) files
using the Compression library.
OPTIONS
-encode
Encode (compress) the input
-decode
Decode (uncompress) the input
-a algorithm
Set the compression algorithm, valid options are zlib, lzma,
lzfse, lz4, lz4_raw. Default is lzfse.
- zlib raw DEFLATE payload, as defined in IETF RFC 1951,
encoder is zlib level 5,
- lzma LZMA2 payload inside a XZ container, encoder is
LZMA2 preset 6,
- lz4 raw LZ4 payload inside a simple frame format
(described in compression.h),
- lz4_raw raw LZ4 payload,
- lzfse LZFSE payload.
-A algorithm
Enable block compression, and set compression algorithm, valid
options are zlib, lzma, lzfse, lz4. Default is lzfse.
-b block_size
Set block size for block compression. The integer value can be
followed by m or k or b.
-t thread_count
Set the number of worker threads to use for block compres-
sion/decompression. Default is the number of logical threads on
the machine.
-i input_file
Input file. If omitted, read from standard input.
-o output_file
Output file. If omitted, write to standard output.
-v Increase verbosity. Default is silent operation.
-h Print usage and exit.
BLOCK COMPRESSION FILE FORMAT
The file starts with a 4-byte header 'p','b','z',<algo>, where <algo>
indicates the algorithm used to compress data. The header is followed
by the 64-bit block size in bytes. Then for each block, we have 64-bit
uncompressed size (will batch the block size, except possibly for the
last block), 64-bit compressed size, and the compressed payload. If
both uncompressed and compressed sizes for a block are equal, the pay-
load is stored uncompressed. All 64-bit values are stored big-endian.
Valid values for <algo> are: 'z' for zlib, 'x' for lzma, '4' for lz4,
and 'e' for lzfse.
COMPRESSION_TOOL(1)