different ways to connect to sqlplus console from remote server

 sqlplus /  as sysdba  ---------------------> from the host server

sqlplus user/passwd@service_or_sid ---------------------> from remote server

sqlplus user/passwd@host:1521/service_or_sid ---------------------> remote server 

to check database status:- 

sudo -iu oracle----> tnsping servicename ----> thats it as per tnsnames.ora entries 

to check server status :-

ping server as per /etc/hosts entries

from shell script 

export OH

export OS

export PATH

export LD_LIBRARY_PATH

sqlplus \/nolog <<< !! > output.txt

conn $constring;

$query;

exit;

!!