copybook-cli

CLI for working with COBOL copybooks and mainframe record data.

copybook supports parsing, inspection, decode/encode, verification, and support-matrix checks.

What it does

• Parse copybooks into machine-readable layout JSON.
• Decode fixed-length and RDW binaries to JSONL with codepage and type controls.
• Encode JSONL back to COBOL binary layout.
• Verify input data and enforce policy/quality checks.
• Inspect feature support and validate compatibility flags.

Commands

Quick start

copybook parse fixtures/copybooks/simple.cpy --output schema.json
copybook decode fixtures/copybooks/simple.cpy fixtures/data/simple.bin \
  --output demo.jsonl --format fixed --codepage cp037
copybook encode fixtures/copybooks/simple.cpy demo.jsonl \
  --output demo.bin --format fixed --codepage cp037
copybook verify fixtures/copybooks/simple.cpy demo.bin \
  --format fixed --codepage cp037

Feature checks

copybook support
copybook support --json
copybook support --check level-88

Field projection

# Decode only selected fields
copybook decode schema.cpy data.bin --output selected.jsonl \
  --format fixed --codepage cp037 --select "CUSTOMER-ID,BALANCE"

Dialect lever

# IBM Enterprise COBOL (zero-tolerant ODO)
copybook decode schema.cpy data.bin --output data.jsonl \
  --format fixed --codepage cp037 --dialect 0

# Micro Focus COBOL (one-tolerant ODO)
copybook parse schema.cpy --dialect 1

Determinism validation

# Verify round-trip determinism
copybook determinism round-trip --format fixed --codepage cp037 schema.cpy data.bin

# JSON output for CI integration
copybook determinism decode --output json --format fixed --codepage cp037 schema.cpy data.bin

Installation

cargo install --path . -p copybook-cli
# Or build locally:
cargo build -p copybook-cli --release

License

Licensed under AGPL-3.0-or-later. See LICENSE.