I've a linux RedHat which contains oracle database. I setted all environnement variables,but when I running sqlplus command I've this error : SP2-0667: Message file sp1<lang>.msb not found

Here are my variables ans my sqlplus commands :

[oracle@as ~]$ echo $ORACLE_HOME /oracle/product/12.1.0/dbhome_1 [oracle@as ~]$ echo $ORA_NLS33 /oracle/product/12.1.0/dbhome_1/nls/data [oracle@as ~]$ echo $LD_LIBRARY_PATH /oracle/product/12.1.0/dbhome_1/lib [oracle@as ~]$ sqlplus Error 6 initializing sql*Plus SP2-0667: Message file sp1<lang>.msb not found SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory[oracle@as ~]$ echo $ORACLE_HOME /oracle/product/12.1.0/dbhome_1 [oracle@as ~]$ echo $ORA_NLS33 /oracle/product/12.1.0/dbhome_1/nls/data [oracle@as ~]$ echo $LD_LIBRARY_PATH /oracle/product/12.1.0/dbhome_1/lib [oracle@as ~]$ sqlplus Error 6 initializing sql*Plus SP2-0667: Message file sp1<lang>.msb not found SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory

Note that I'm currently running as oracle user,which seems to be the owner of the /oracle folder with read and excecute permission. I also seen that a file named sp1us.msb exists in the following folder :

[oracle@as ~]$ find $ORACLE_HOME | grep sp1 /oracle/product/12.1.0/dbhome_1/sqlplus/mesg/sp1us.msb /oracle/product/12.1.0/dbhome_1/sqlplus/mesg/sp1us.msg[oracle@as ~]$ find $ORACLE_HOME | grep sp1 /oracle/product/12.1.0/dbhome_1/sqlplus/mesg/sp1us.msb /oracle/product/12.1.0/dbhome_1/sqlplus/mesg/sp1us.msg