ASM Default Disk String location .... 

Operating System           Default Search String

===============                  ===================

Solaris (32/64 bit)       /dev/rdsk/*
Windows NT/XP             \\.\orcldisk*
Linux (32/64 bit)         /dev/raw/*
HP-UX                     /dev/rdsk/*
HP-UX(Tru 64)             /dev/rdisk/*
AIX                       /dev/rhdisk/*

connect sqlplus without tnsname.ora file .... 

sqlplus user/pass@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.85.132)(Port=1521))(CONNECT_DATA=(SID=MYSID)))

sqlplus "user/pass@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.85.132)(Port=1521))(CONNECT_DATA=(SID=MYSID)))"

sqlplus 'user/pass@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.85.132)(Port=1521))(CONNECT_DATA=(SID=MYSID)))'


sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.85.132)(Port=1521))(CONNECT_DATA=(SID=vihaan))) as sysdba'

ww
 sqlplus 'sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=xxxx)(Port=1521))(CONNECT_DATA=(SID=rac2))) as sysdba'


 sqlplus /nolog


idle sqlplus> connect sys@'(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xxxx)(PORT=1521)) (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=RAC)))' as sysdba
Enter password:
Connected.

connect sys with password .... 

  sqlplus 'sys/sys@prim as sysdba'

sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.85.132)(Port=1521))(CONNECT_DATA=(SID=vihaan))) as sysdba'

to connect pluggable database as sys 
[oracle@cloud-ora ~]$ sqlplus 'sys/vih**n123@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=119.18.114.253)(Port=1521))(CONNECT_DATA=(SERVICE_NAME=anuj))) as sysdba'

SQL*Plus: Release 12.2.0.1.0 Production on Thu Jul 5 15:01:06 2018

Copyright (c) 1982, 2016, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

===

sqlplus sys/"test1cdTE*"@anujz as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Wed Jul 3 02:25:15 2024

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Last Successful login time: Tue Jul 02 2024 05:10:46 -04:00

Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

primary:sys@vihcdbd8-vihcdbd8 sqlplus>

ww
sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.0.70)(Port=1521))(CONNECT_DATA=(SID=FREE))) as sysdba'

ww
sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.0.70)(Port=1521))(CONNECT_DATA=(SID=FREE) (SERVICE_NAME= FREEPDB1))) as sysdba'

sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.0.70)(Port=1521))(CONNECT_DATA=(SID=FREE))) as sysdba'

SQL*Plus: Release 23.0.0.0.0 - Production on Sat Nov 11 12:40:28 2023

Version 23.3.0.23.09

Copyright (c) 1982, 2023, Oracle.  All rights reserved.

Connected to:

Oracle Database 23c Free Release 23.0.0.0.0 - Develop, Learn, and Run for Free

Version 23.3.0.23.09

SQL> Disconnected from Oracle Database 23c Free Release 23.0.0.0.0 - Develop, Learn, and Run for Free

Version 23.3.0.23.09

[oracle@localhost ~]$

[oracle@localhost ~]$ sqlplus 'sys/sys@(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(Host=192.168.0.70)(Port=1521))(CONNECT_DATA=(SID=FREE) (SERVICE_NAME= FREEPDB1))) as sysdba'

SQL*Plus: Release 23.0.0.0.0 - Production on Sat Nov 11 12:41:25 2023

Version 23.3.0.23.09

Copyright (c) 1982, 2023, Oracle.  All rights reserved.

Connected to:

Oracle Database 23c Free Release 23.0.0.0.0 - Develop, Learn, and Run for Free

Version 23.3.0.23.09

-===

sqlplus 'sys/sys@stdy as sysdba'
sqlplus sys/sys@stdy as sysdba
sqlplus sys/sys@'stdy as sysdba'
sqlplus sys/sys@'stdy' as sysdba


====
rman

run {
allocate channel d0_1 device type disk maxopenfiles 32 connect 'sys/sys@//192.168.0.28:1521/orcl' ;
DELETE EXPIRED ARCHIVELOG ALL;

release channel d0_1;
}
list backup summary;


=

unset TWO_TASK
conn hr/hr@//localhost:1521/freepdb1
Connected.


or with ip 

 sqlplus hr/hr@//192.168.0.70:1521/freepdb1



export ORACLE_PDB_SID=FREEPDB1

[oracle@localhost ~]$ sqlplus / as sysdba