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9.1   Options

-o, --output=FILE

Specifies the output file name. Without this option, output will go to craff.out. A hyphen (-) means standard output, and implies -q. Writing to standard output is only possible in raw format (-d) or when writing a content map (-l).

-d, --decompress

Causes the output to be an ordinary (raw) file. The default is to output in the craff format. When this option is given, any holes in the output are filled with zero bytes.

-l, --content-map

Writes a human-readable map of the input files to the output. Blocks are marked D where data is present, and . (dot) where not.

-D, --diff

Instead of merging the input files, output the difference between the input files as a craff file. There must be exactly two input files. The output is the file that, when merged with the first file, would result in the second file. The input files may be in craff or raw format.

-z, --zero-fill-gaps

Fills gaps with zero bytes and marks them as present. Without this option, a gap in all input files will remain a gap in the output file.

-Z, --omit-zero-blocks

Treats blocks that consist entirely of zero bytes as empty in the output (i.e., they will be output as holes).

-b, --block-size=SIZE

Specifies the output block size in bytes. The size must be a power of 2, and may be specified in kilobytes using 'k' as a suffix. Without this option, the block size will be the smallest of the input files' block sizes.

This is the smallest unit of storage in a craff file. Larger values compress better, but will waste more space if only part of the block is present. A block size of at least 4k is recommended.

-s, --sub-block-size=SIZE

Specifies the output sub-block size in bytes. The size must be a power of 2, and may be specified in kilobytes using 'k' as a suffix. Without this option, the block size will be the smallest of the input files' sub-block sizes.

This is the smallest unit of granularity in a craff file. Smaller values allow more fine-grained control of what data is present, but uses more space. For disk dumps, the sector size is useful (often 512 bytes); for memory dumps, use the page size (such as 4k or 8k).

-i, --dir-entries=N

Specifies the number of entries in each directory node. Must be a power of 2.

-c, --compression=COMPRESSION

Specifies the compression type: none, zlib, or bz2. No compression is fastest, bz2 is smallest but slow, and zlib is a good compromise. The default is zlib. (In practice, zlib is often better than bz2 unless the block size is large.)

-e, --extract=START

Extracts a block to the output file. The extracted block starts at file offset START and the size is given by --extract-block-size. The output is in raw format.

-w, --extract-block-size=SIZE

Size of block to extract with --extract.

-n, --info

Displays file information for each of the input files to the standard output.

-q, --quiet

Suppresses the progress indicator.

-v, --version

Displays version information of the craff utility itself.

-h, --help

Displays a summary of the command-line options.

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