How to connect to oracle 12c from sqlplus without password in command line

This may seem as weird question:

If i have user called demo with password Pass1234

When connecting to oracle 11g I can run sqlplus like this with password in command line:
on DB host:

C:\> sqlplus demo/Pass1234

Or remote machine

C:\> sqlplus demo/Pass1234@:1521/orcl

I can do so without give the password in command line and expose it like this:

C:\> sqlplus demo

Then I get:

SQL*Plus: Release 11.1.0.7.0 bla bla bla
Copyright (c) bla bla bla
Enter password:

Then I can enter the password manually.

When connecting to Oracle 12c I can connect like this from any machine (with password):

C:\> sqlplus demo/Pass1234@:1521/pdborcl

My question is: How to connect to Oracle 12c without tnsnames.ora edit and without write the password in the command line?

I also havn't figured out yet if it is possible to connect to Oracle 12c from sqlplus on the DB host machine without give the IP or localhost, and without editing the tnsnames.ora, like I can do in Oracle 11g?

And more thing, can I do so from a remote machine (even to Oracle 11g) without using a full connect?

(means to give user and db connection in command line and password manually, not like use /NOLOG in command and then: SQL> connect demo/Pass1234@:1521/pdborcl)

Thanks!

This answer based on a1ex07 comment:

given the folowing detailes:

user name: demo
password: Pass1234
ip: 1.2.3.4
listener port: 1521
oracle SID: orcl
pdb service name: pdborcl

connect to core db from db host as sysdba:

• without need of password: sqlplus / as sysdba

• password manually: sqlplus sys as sysdba

• password in command: sqlplus sys/Pass1234 as sysdba

connect to core db from db host or remote as sysdba:

• password manually: sqlplus sys@\"1.2.3.4:1521/orcl\" as sysdba

• password in command: sqlplus sys/Pass1234@1.2.3.4:1521/orcl as sysdba

connect to pdb from db host or remote as sysdba:

• password manually: sqlplus sys@\"1.2.3.4:1521/pdborcl\" as sysdba

• password in command: sqlplus sys/Pass1234@1.2.3.4:1521/pdborcl as sysdba

connect to pdb from db host or remote as demo (regular user):

• password manually: sqlplus demo@\"1.2.3.4:1521/pdborcl\"

• password in command: sqlplus demo/Pass1234@1.2.3.4:1521/pdborcl

StackExchange Database Administrators Q#140032, answer score: 12