how to check variable equals to a string bash code example

Example 1: test string equality bash

strval1="Ubuntu"
strval2="Windows"

#Check equality two string variables

if [ $strval1 == $strval2 ]; then
  echo "Strings are equal"
else
  echo "Strings are not equal"
fi

#Check equality of a variable with a string value

if [ $strval1 == "Ubuntu" ]; then
  echo "Linux operating system"
else
  echo "Windows operating system"
fi

Example 2: bash compare two strings

if [ "$s1" == "$s2" ]
then
	stuff
fi