Which shell is used for programming langauge ?

Bash shell (bash), Bourne shell(sh), C shell(csh), Bourne Again Shell (bsh), Korn shell(ksh) etc

Most commonly we use Kshell and bashell for programming languages. Shell scripting based the operating system being installed.

There are different types of shell are available in unix.most commonly we use Kshell and bashell for programming languages.

it's up to you to choose , the most common environment to your shell script ( programming under Unix or Linux as you called ) are bash (#!/bin/bash) in Linux OS and  Korn in Unix (#!/bin/ksh) , however you have others like sh, csh and zsh ... , the most important this is to know how modify , customize and write your script in your shell.

If I've understood it correctly, you want to write code in Unix. For that you can use any shell like bash or ksh.

bash shell, korn shell interfaces are used for programming languages.

The shell gives us an interface to the Unix system and there are different types of shells - Bourne shell(sh), C shell(csh), Bourne Again Shell (bsh), Korn shell(ksh) etc all of which are used for programming language.

CLI command line interface is used for most programming languages.