How should I work with CLOB or NCLOB datatype in oracle?

I read these datatypes are for storing long String, so I decided to use NCLOB for storing comments and Bio.I just wanted to try, I created a table :

create table cmd(content NCLOB);

and tried to insert a long string in the table but just three line is inserted. something like this picture :

Did I use NCLOB in wrong way?What is the correct way?

Your data has been inserted correctly, before selecting from your table in sqlplus use the following:

set long 9000
select * from cmd;

Here is a link to the documentation: https://docs.oracle.com/database/121/SQPUG/ch_twelve040.htm#SQPUG088

Cheers