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How to use gdb in Ubuntu Terminal

Here's a practical, minimal guide for using GDB in Ubuntu terminal — from launching to setting breakpoints and navigating your code. 🧰 Step 1: Compile with Debug Symbols Use -g and disable optimizations ( -O0 preferred for debugging): bash Copy Edit g++ -g -O0 -o myprog myprog.cpp 🚀 Step 2: Launch GDB bash Copy Edit gdb ./myprog You'll see a (gdb) prompt. 🎯 Step 3: Set Breakpoints You can set breakpoints in three main ways : ✅ a. At a function gdb Copy Edit (gdb) break main ✅ b. At a specific file and line gdb Copy Edit (gdb) break myprog.cpp:42 ✅ c. At a method in a class gdb Copy Edit (gdb) break MyClass::doSomething If the symbol is mangled (C++), GDB usually demangles automatically, especially if compiled with -g . ▶️ Step 4: Run the Program gdb Copy Edit (gdb) run 🧭 Step 5: Navigate Command Meaning next or n Step over current line step or s Step into function call finish Run until current function returns continue or c Continue until...
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Directly collecting payment from upi from ecomm/subscription webiste without involving payment gateway: Discussion with chatGpt

Query:

I hv gst n current ac
I wn something like business upi (gpay, phpay, amzpay, etc) for which I cn do some kind of api programming. And generate dynamic upi qr code in my website/ecomm/etc to for customer bill for bill amt. Customer cn scan that qr code n pay directly in my ca ac.
No middle payment gateway involved, so no need to pay outsider any money.
Is it possible in india upi via any upi api, etc directly?

 

Yes, it is possible in India to integrate UPI-based payment collection using dynamic UPI QR codes without a traditional payment gateway, but there are caveats. Here's a deep dive from both developer and business perspectives.

✅ Your Goal

You want to:

  • Collect UPI payments directly into your Current Account (CA) (linked with GSTIN).

  • Generate dynamic UPI QR codes or UPI payment links (with customer-specific amounts and descriptions).

  • Avoid using Razorpay, Instamojo, Paytm Biz, etc. — no third-party commission.

  • Use APIs (GPay-style functionality) from your own backend/frontend.

✅ Is It Technically Possible in India?

✔ Yes, through the UPI Deep Link / Intent format:

UPI allows you to generate deep links and QR codes which any app (GPay, PhonePe, Paytm, etc.) can scan.

✅ Format (UPI Deep Link):

upi://pay?pa=your-vpa@bank&pn=Your+Business+Name&mc=0000&tid=txn123&tr=orderid123&tn=Invoice+12345&am=199.00&cu=INR

✅ Dynamic QR Code:

Just convert this UPI link to a QR code using any QR library like qrcode (Python), qrcode.js, etc.
✅ Example (for your server-side logic):

import qrcode

upi_id = "yourvpa@icici"  # Your UPI VPA linked to your current account
amount = 250.75
txn_note = "Order #78910"

upi_url = f"upi://pay?pa={upi_id}&pn=Your+Name&am={amount}&cu=INR&tn={txn_note}"
img = qrcode.make(upi_url)
img.save("upi_qr_order_78910.png")

This QR will work with Google Pay, PhonePe, etc. — no API integration needed.
🧩 How to receive payment programmatically?

Here's the real bottleneck:

    UPI does NOT natively provide real-time transaction confirmation via a public API.

You have 2 options:
✅ Option 1: Use Bank’s UPI API (ideal but harder to get)

Some banks (e.g., Axis, ICICI, HDFC) offer merchant UPI APIs to trusted businesses. These APIs:

    Allow you to generate UPI requests (intent/deep link).

    Provide callback/webhook when payment is received.

    No third-party like Razorpay.

➡ But:

    Usually requires you to be an established business with bank approval.

    May involve minimal monthly charges.

    You’ll need to sign an API agreement with the bank.

👉 You can approach your current bank (linked to your CA) and ask about:

    “UPI Collect API or merchant UPI integration for direct UPI payment collection.”

Some banks offering this (2024-25):

    ICICI (InstaBIZ APIs)

    Axis (API Banking via Developer Portal)

    HDFC (Partner APIs)

    Yes Bank (UPI PSP services)

✅ Option 2: Use UPI polling via SMS/email reconciliation

If bank APIs are denied:

    You accept UPI payments via QR code.

    After payment, the customer is shown a “Paid” screen on their app.

    You poll bank SMS/inbox or use webhook from SMS gateway to parse payment info (customer name, UTR, amount).

You match payment details with the order DB.

    Not ideal for automation, but works for small-scale use.

🛠 Some developers use:

    Twilio or Gupshup to parse SMS (from bank).

    OR use IMAP access to email inbox for transaction alert parsing.

⚙️ Realistic Implementation Plan (for You)
Option A: Quick MVP (no API)

    Generate dynamic UPI link + QR using backend code.

    Customer scans via any UPI app and pays.

    You manually or semi-automatically verify payments using bank SMS/email parsing.

    Match transaction UTR with order.

Option B: Long-term (via Bank API)

    Contact your bank manager – request access to UPI Collect API for your GST current account.

    Implement:

        Create UPI request.

        Receive success/failure webhook.

        Auto reconcile in your app.

🧠 Example Use Case for Monetization

Build a white-label e-commerce backend or invoice portal:

    Merchants register (you charge ₹X/month).

    They enter order amount, generate dynamic UPI QR.

    You generate and serve QR via API.

    They match UPI UTR from their bank; your backend helps reconcile.

💰 Revenue model: Charge per month or per active merchant.
🚨 Caution

    Don't use "collect requests" unless via official UPI API. Many apps block unknown handles.

    Avoid scraping third-party apps — not allowed.

🔍 Banks You Can Contact
Bank	API Portal	Note
ICICI	https://developer.icicibank.com	Has full UPI API
Axis	https://developer.axisbank.com	Offers UPI APIs
HDFC	Via corporate relationship	Email required
Yes Bank	PSP for BharatPe, PhonePe, etc.	Strong UPI infra
✅ Summary
Feature	Possible Without Gateway?
UPI QR with amount	✅ Yes
UPI link with amount	✅ Yes
API confirmation of payment	❌ Not public, only via bank APIs
Webhook on payment success	✅ Only via bank API
Fully automated system	✅ With bank API

 

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