세션 ID : dthcuv1ied57uk44qm1augv8hf
session1 :
Warning: Undefined array key "session1" in /users/2018/i1858006/public_html/2019/webprog/ch10/exam10-06.php on line 16

session2 :
Warning: Undefined array key "session2" in /users/2018/i1858006/public_html/2019/webprog/ch10/exam10-06.php on line 17

session3 :
Warning: Undefined array key "session3" in /users/2018/i1858006/public_html/2019/webprog/ch10/exam10-06.php on line 18

세션 설정
세션 확인
모든 세션 변수 삭제
세션 삭제