Bash: check if string contains substring

• method 1:

  if [[ $str == *"AAA"* ]]; then
      echo "yes"
  else
  	echo "no"
  fi
  	

• method 2:

  if [[ $str =~ "AAA" ]]; then
      echo "yes"
  else
  	echo "no"
  fi
  	

see also

• How to check if a string contains a substring in Bash