invokehello.ts

import {
  clusterApiUrl,
  Connection,
  Keypair,
  LAMPORTS_PER_SOL,
  PublicKey,
  sendAndConfirmTransaction,
  Transaction,
  TransactionInstruction,
  TransactionSignature,
} from "@solana/web3.js";
import base58 from "bs58";
import Dotenv from "dotenv";
Dotenv.config();

let programId = new PublicKey("<YOUR_PROGRAM_ID>");

const connection = new Connection(clusterApiUrl("devnet"), "confirmed");

async function main() {
  const secret = process.env.PRIVATE_KEY || "";
  const secretKey = base58.decode(secret);
  const payer = Keypair.fromSecretKey(secretKey);

  await connection.requestAirdrop(payer.publicKey, LAMPORTS_PER_SOL * 1);

  const transactionSignature = await sayHello(payer);

  console.log(
    `Transaction: https://explorer.solana.com/tx/${transactionSignature}?cluster=devnet`
  );
}

main()
  .then(() => {
    console.log("Finished successfully");
  })
  .catch((error) => {
    console.error(error);
  });

export async function sayHello(payer: Keypair): Promise<TransactionSignature> {
  const transaction = new Transaction();

  const instruction = new TransactionInstruction({
    keys: [],
    programId,
  });

  transaction.add(instruction);

  const transactionSignature = await sendAndConfirmTransaction(
    connection,
    transaction,
    [payer]
  );

  return transactionSignature;
}