Oracle job of type EXECUTABLE failed with exit code: Permission denied

Created schedule job

BEGIN
DBMS_SCHEDULER.create_job
(job_name => 'DF_Partitions',
repeat_interval => 'FREQ=HOURLY;INTERVAL=2',
job_type => 'EXECUTABLE',
job_action => '/home/osadmin/bin/df.sh',
enabled => TRUE,
comments => 'Check Partitions on System'
);
END;

set permission on file
#chown oracle:dba /home/osadmin/bin/df.sh
#chmod 750 /home/osadmin/bin/df.sh

But I found "ORA-27369: job of type EXECUTABLE failed with exit code: Permission denied " in schedule log.

So, I resolve that i changed permission on $ORACLE_HOME/bin/extjob file.
#chown oracle:dba $ORACLE_HOME/bin/extjob