check wheter a string contains a substring bash script code example

Example 1: checking if a substring exists in a string bash

string='Haystack';

if [[ $string =~ "Needle" ]]
then
   echo "It's there!"
fi

Example 2: bash if substring

string='Hi substring' #To check if string has "Mylong" substring do
if [[ $string == *"substring"* ]]; then
  echo "String has substring"
fi