unspent

#!/bin/bash
# UTXO checker for Bitcoin mainnet
api=https://blockstream.info/api

function usage()
{
  cat <<-EOF
  usage: $(basename $0) tx_id index
EOF
}

commands='jq curl'
for c in $commands; do
  hash $c || { echo "install $c"; exit 255; }
done

tx=$1
index=$2

[ -n "$tx" ] || { usage; exit 255; }
[ -n "$index" ] || { usage; exit 255; }

result=$(curl -s "${api}/tx/$tx/outspends" | jq ".[${index}].spent")

[ "$result" = "null" ] && { echo 'invalid'; exit 255; }

value=$(curl -s "${api}/tx/$tx" | jq ".vout[${index}].value")

[ "$result" = "false" ] && { echo "$value unspent"; exit 0; }
[ "$result" = "true" ] && { echo "$value spent"; exit 1; }