Simple High-speed ARChiver
sharc is a very fast file archiver, using the density compression library. It is ideal when speed is paramount, followed by compression ratio - although excellent ratios can be achieved with certain settings on low entropy data.
sharc uses parallel processing to achieve maximum encode/decode performance, and is thus particularly efficient with large files. Data integrity is verified using the fast, non-cryptographic seahash hashing algorithm.
sharc can be built on rust-compatible platforms. First use rustup to install rust.
a) get the source code:
git clone https://github.com/g1mv/sharc.git
cd sharcb) build and print help:
RUSTFLAGS="-C target-cpu=native" cargo build --release
target/release/sharc -hThe .sharc file format consists of a header, followed by a sequence of blocks. The header has the following structure:
| Header | Algorithm used | Block size MB |
|---|---|---|
| 5 bytes | 1 byte | 2 bytes |
The sequence of blocks has the following structure:
| Encoded block size (ebs) | Encoded block | Block hash |
|---|---|---|
| 8 bytes | {ebs} bytes | 8 bytes |
To compress a file named 'test.file' into 'test.file.sharc' using the default algorithm (density cheetah):
sharc test.file
To decompress 'test.file.sharc',
unsharc test.file.sharc
Compression algorithm can be selected with the -a option.
| Algorithm | Speed rank | Ratio rank |
|---|---|---|
| chameleon | 1st | 3rd |
| cheetah | 2nd | 2nd |
| lion | 3rd | 1st |
For example, to use the fastest available algorithm (density chameleon):
sharc -a chameleon test.file
For further information on all other options:
sharc -h