lz4c

A pure-Go CLI for go-compressions/lz4 — the LZ4 block format on the command line, as a single CGO-free static binary. Repository →

Usage

lz4c [-d] [-i input] [-o output] [-v]

• Compresses by default; -d / --decompress decompresses.

• -i / --input defaults to stdin.

• -o / --output defaults to stdout.

• -v / --verbose prints a summary line to stderr with byte counts, compression ratio (compress only), and elapsed time:

  compressed 65536 → 12345 bytes (18.8%) in 4.231ms
  decompressed 12345 → 65536 bytes in 1.872ms

  Without -v, lz4c stays silent so the binary output on stdout is safe to pipe.

Examples

# Compress a file to disk.
lz4c -i big.bin -o big.bin.lz4

# Round-trip through a pipe.
cat big.bin | lz4c | lz4c -d > restored.bin

# Show timing + ratio.
lz4c -v -i big.bin -o big.bin.lz4

Container format

The lz4 library exposes the LZ4 block codec only, which does not record the decompressed length. lz4c frames each block with a fixed 12-byte header so a stream is self-describing:

magic   [4]byte  // "LZ4C"
rawLen  uint64   // little-endian length of the original data
...block...      // a standard LZ4 block, byte-for-byte

The payload after the header is an unmodified, standard LZ4 block and stays wire-compatible with pierrec/lz4: strip the 12-byte header and any LZ4 block decoder consumes the remainder.

Build

go build ./cmd/lz4c        # or: task build

Coverage

task test reports 100% statement coverage across all three packages:

The package ships a Taskfile (task lint|build|test|ci) used by both local development and CI; Renovate auto-merges patch/minor gomod updates.

License

BSD-3-Clause.