how to variables in bash code example

Example 1: assign a variable in bash

#!/bin/bash
# Naked variables

echo

# When is a variable "naked", i.e., lacking the '$' in front?
# When it is being assigned, rather than referenced.

# Assignment
a=879
echo "The value of \"a\" is $a."

# Assignment using 'let'
let a=16+5
echo "The value of \"a\" is now $a."

echo

# In a 'for' loop (really, a type of disguised assignment):
echo -n "Values of \"a\" in the loop are: "
for a in 7 8 9 11
do
  echo -n "$a "
done

echo
echo

# In a 'read' statement (also a type of assignment):
echo -n "Enter \"a\" "
read a
echo "The value of \"a\" is now $a."

echo

exit 0

Example 2: print variable in bash

#!/bin/bash  
echo  
echo "When single quote is used with string:"  
invitation='Welcome to javatpoint'  
echo $invitation  
echo  
echo "When double quote is used with string:"  
invitation="Welcome to javatpoint"  
echo $invitation  
echo  
echo "When variable is used with double quote:"  
Remark="Hello User!, $invitation"  
echo $Remark  
echo  
echo "When variable is used with single quote:"  
Remark='Hello User!, $invitation'  
echo $Remark  
echo