ORA-12560: TNS:protocol adapter error

I am receiving below error message when i try to connect to ORACLE through sqlplus.

sqlplus "/nolog"

connect sys as sysdba

ERROR:
ORA-12560: TNS:protocol adapter error


to resolved this i set ORACLE_SID parameter
set ORACLE_SID=EP6

sqlplus "/nolog"
connect sys as sysdba

this time i succeed with login.

Datafile usage in tablespace

select substr(a.file_name,1,30),
substr(a.tablespace_name,1,20),
a.bytes allocated,
nvl(b.free,0) free,
a.bytes-nvl(b.free,0) used,
(nvl((a.bytes-nvl(b.free,0)),0)*100)/a.bytes usage_perc
from dba_data_files a,
( select file_id, sum(bytes) free
from dba_free_space
group by file_id ) b
where a.file_id = b.file_id (+)
AND a.tablespace_name='&tablespace'
/

Mount USB Pen Drive in to Linux.

Before plug in USB pen see /var/log/messages kernel through which you get device name and path. Here I get sdc as device name (or sda0, sda1 like that.).

Now mount it.

Mount for FAT file system
mount –t vfat /dev/sdc /mnt/mounttemp/

Mount for NTFS file system
mount –t ntfs /dev/sdc /mnt/mounttemp/

access your device