Comparing two string variables in an if statement in Bash

Question

So, I'm trying to compare 2 string variables using if statement and trying to get it to work in Bash.

#!/bin/bash

s1="hi"
s2="hi"

if ["$s1" == "$s2"]
then
  echo match
fi

I've tried many things, using [["$s1" == "$s2"]], with and without quotes, using =, == and -eq, but I still get the following error:

[hi: command not found

Answer 1

1. For string comparison, use:

if [ "$s1" == "$s2" ]

For the a contains b, use:

2. if [[ $s1 == *"$s2"* ]]