sed -i 's/utf8mb4_0900_ai_ci/utf8_general_ci/g' YOUR_SQL_FILE_NAME.sql
sed -i 's/CHARSET=utf8mb4/CHARSET=utf8/g' YOUR_SQL_FILE_NAME.sql
Note : After runing above command you are getting similar this sed: 1: "YOUR_SQL_FILE_NAME.sql": invalid command code Y
