As you Asking for the Procedure to Linking the Adhar Card to the HDFC Bank the procedure is as follow

you may link your Adhar Card to the HDFC Bank With Following Ways

Offline Mode

Prior to linking your Aadhaar Card to your HDFC Bank account via the offline route, you will have to keep certain documents ready such as your bank passbook, your E-Aadhaar or Aadhaar Card, and the Application Form for linking your Aadhaar Card to your HDFC Bank account.
. Once you have duly filled in the form, you will have to visit a branch of HDFC Bank and submit the application form as well as photocopy of your Aadhaar Card to a representative of the bank.

Your original Aadhaar Card will also have to be furnished in case the officials request the same.

The bank will retain the application form along with a photocopy of the Aadhaar Card to carry out further verification checks.

Once the bank has verified all of your information, your Aadhaar Card will be successfully linked to your HDFC Bank account

Online Mode :

All you need to link your Aadhaar Card to your HDFC Bank account via the online mode is a working HDFC Internet Banking account.

The first step in the process is to login to your HDFC Internet Banking account, then click on 'Link Aadhaar Card Details ', after which you will be directed to the online form where you will have to enter the required information and complete the linking process.

For Any Queries you may Contact on the Following Number

HDFC Bank
Customer Care Number
1800 22 1006 or (022) 6160 6161