import java.io.*;
import java.util.*;

public class CommandExection {

public static void Command(String commandline) {

try {

String line;

Process p = Runtime.getRuntime().exec(commandline);

BufferedReader input =

new BufferedReader

(new InputStreamReader(p.getInputStream()));

while ((line = input.readLine()) != null) {

System.out.println(line);

}

input.close();

}

catch (Exception err) {

err.printStackTrace();

}
}

Here is the basic code:

create or replace and compile Java Source named "OSCommand" as
-- java:        OS COMMAND
-- descr:       Executes an Operating System Command using the JAVA RTS
--
-- IN parameter:        os command to execute (including fully qualified path names)
-- OUT parameter:       returncode [\nstring]
--                      where string a max of 32000 chars of the output of the command
--                      (note that \n is used as separators in the string)
--
--                      returncode=-1   Java RTS error occurred (e.g. command does not exist)
--                      returncode=255  o/s command failed (e.g. invalid command params)
--
--
import java.io.*;
import java.lang.*;
public class OSCommand{


        public static String Run(String Command){

                Runtime rt = Runtime.getRuntime();
                int     rc = -1;

                try{

                        Process p = rt.exec( Command );
                        int bufSize = 32000;
                        int len = 0;
                        byte buffer[] = new byte[bufSize];
                        String s = null;

                        BufferedInputStream bis = new BufferedInputStream( p.getInputStream(), bufSize );
                        len = bis.read( buffer, 0, bufSize );

                        rc = p.waitFor();

                        if ( len != -1 ){
                                s = new String( buffer, 0, len );
                                return( s );
                        }

                        return( rc+"" );
                }

                catch (Exception e){
                        e.printStackTrace();
                        return(  "-1\ncommand[" + Command + "]\n" + e.getMessage() );
                }

        }
}
/
show errors

create or replace function OSexec( cCommand IN string ) return varchar2 is
-- function:    OS EXEC
-- descr:       PL/SQL wrapper for the Java OSCOMMAND stored proc
--
language        JAVA
name            'OSCommand.Run(java.lang.String) return java.lang.String';
/
show errors


-- Punching a hole into the Java VM sandbox. The following must be run as 
-- sysdba. Substitute SCOTT with the applicable schema that owns the OSEXEC
-- and OSCOMMAND stored procs.
declare
        SCHEMA  varchar2(30) := 'SCOTT';
begin
        dbms_java.grant_permission(
                SCHEMA,
                'SYS:java.io.FilePermission',
                '<<ALL FILES>>',
                'execute'
        );

        dbms_java.grant_permission(
                SCHEMA,
                'SYS:java.lang.RuntimePermission',
                'writeFileDescriptor',
                '*'
        );

        dbms_java.grant_permission(
                SCHEMA,
                'SYS:java.lang.RuntimePermission',
                'readFileDescriptor',
                '*'
        );

commit;
end;
/

-- example: running the Unix/Linux date command to get the current date and time
SQL> select OSexec('/usr/bin/date') as STDOUT from dual;

STDOUT
----------------------------------------------------
Fri Sep  1 08:09:34 SAST 2006

1 row selected.

SQL>