Cardano Cli Plutus Scripts

Datum handling

• Inline datum: Stored on-chain with UTxO
• Datum hash: Only hash on-chain, provide full datum when spending
• No datum: For some V3 scripts

Collateral

• Required for all Plutus script transactions
• Must be ADA-only UTxO
• Forfeit if script fails unexpectedly
• Typically 1-5 ADA sufficient

Workflow templates

Lock funds at script address

# 1. Derive script address
cardano-cli conway address build \
  --payment-script-file script.plutus \
  --testnet-magic 1 \
  --out-file script.addr

# 2. Create datum file
echo '{"constructor": 0, "fields": []}' > datum.json

# 3. Lock with inline datum
cardano-cli conway transaction build \
  --testnet-magic 1 \
  --tx-in <utxo>#<index> \
  --tx-out "$(cat script.addr)+5000000" \
  --tx-out-inline-datum-file datum.json \
  --change-address <payment-addr> \
  --out-file tx.unsigned

# Sign and submit

Spend from script

# 1. Create redeemer
echo '{"constructor": 0, "fields": []}' > redeemer.json

# 2. Build script spend
cardano-cli conway transaction build \
  --testnet-magic 1 \
  --tx-in <script-utxo>#<index> \
  --tx-in-script-file script.plutus \
  --tx-in-inline-datum-present \
  --tx-in-redeemer-file redeemer.json \
  --tx-in-collateral <collateral-utxo>#<index> \
  --tx-out <recipient>+<amount> \
  --change-address <payment-addr> \
  --out-file tx.unsigned

# Sign (with collateral key) and submit

With reference script

# Script already on-chain at reference UTxO
cardano-cli conway transaction build \
  --testnet-magic 1 \
  --tx-in <script-utxo>#<index> \
  --spending-tx-in-reference <ref-script-utxo>#<index> \
  --spending-plutus-script-v2 \
  --spending-reference-tx-in-inline-datum-present \
  --spending-reference-tx-in-redeemer-file redeemer.json \
  --tx-in-collateral <collateral>#<index> \
  --tx-out <recipient>+<amount> \
  --change-address <payment-addr> \
  --out-file tx.unsigned

Examples

Example: Simple validator spend

User request: "Spend from my always-succeeds script"

Response:

# === Spend from Always-Succeeds Script ===

SCRIPT_ADDR=$(cat script.addr)
PAYMENT_ADDR=$(cat base.addr)

# 1. Query script UTxO
cardano-cli conway query utxo \
  --address $SCRIPT_ADDR \
  --testnet-magic 1
# Note the UTxO hash and index

# 2. Query payment UTxOs (for collateral)
cardano-cli conway query utxo \
  --address $PAYMENT_ADDR \
  --testnet-magic 1
# Select ADA-only UTxO for collateral

# 3. Create redeemer (for always-succeeds, can be unit)
echo '{"constructor": 0, "fields": []}' > redeemer.json

# 4. Build transaction
cardano-cli conway transaction build \
  --testnet-magic 1 \
  --tx-in <script-utxo>#0 \
  --tx-in-script-file always-succeeds.plutus \
  --tx-in-inline-datum-present \
  --tx-in-redeemer-file redeemer.json \
  --tx-in-collateral <collateral-utxo>#0 \
  --tx-out "$PAYMENT_ADDR+4500000" \
  --change-address $PAYMENT_ADDR \
  --out-file tx.unsigned

# 5. Sign and submit (use operator skill)

Debugging

Calculate execution costs

cardano-cli conway transaction build \
  ... \
  --calculate-plutus-script-cost costs.json

cat costs.json | jq .

Common failures

• ExUnitsTooBig: Script exceeds execution budget
• CollateralNotFound: Missing or invalid collateral
• DatumMismatch: Provided datum doesn't match hash
• ScriptFailure: Validator returned False

Safety / key handling

• Test scripts on preprod/preview first
• Use minimal collateral
• Datum/redeemer are public—no secrets
• Verify script hash after rebuilds

References

• shared/PRINCIPLES.md
• cardano-cli-plutus-scripts-operator (for execution)
• aiken-smart-contracts (for writing validators)