Got it...................
db2 -x "select 'db2 restore db TESTDB from /home/db2server01/backup/ taken at', (SELECT START_TIME FROM TABLE(SYSPROC.ADMIN_LIST_HIST()) AS backup_time where OPERATION='B' Order by START_TIME desc fetch first 1 rows only), 'replace existing;' FROM SYSIBM.SYSDUMMY1"