在Oracle运行操作系统命令

在Oracle 8i中,往往会出现要在存储过程中运行操作系统命令的情况.一般来说,利用Oracle Enterprise Manager设定作业时可以达到这个目的.但是由于OEM在设定作业缺乏灵活性,设定的作业的参数是固定的.在实际应用当中往往需要在SQL语句当中运行需要随时运行操作系统命令.Oracle 8i没有直接运行OS命令的语句,我们可以利用DBMS_PIPE程序包实现这一要求.

DBMS_PIPE通过创建管道,可以让至少两个进程进行通信.Oracle的管道与操作系统的管道在概念上有相同的地方,但是在实现机制不同.

下面介绍实现具体步骤:

1 创建一个程序包,姑且起名叫DAEMON,SQL语句如下:

/*创建daemon程序包*/

CREATE OR REPLACE PACKAGE BODY daemon AS

/*execute_system是实现运行os命令的函数*/

FUNCTION execute_system(command VARCHAR2,

timeout NUMBER DEFAULT 10)

RETURN NUMBER IS

status NUMBER;

result VARCHAR2(20);

command_code NUMBER;

pipe_name VARCHAR2(30);

BEGIN

pipe_name := DBMS_PIPE.UNIQUE_SESSION_NAME;

DBMS_PIPE.PACK_MESSAGE('SYSTEM');

DBMS_PIPE.PACK_MESSAGE(pipe_name);

DBMS_PIPE.PACK_MESSAGE(command);

/*向daemon管道发送表示命令的字符*/

status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout);

IF status <> 0 THEN

RAISE_APPLICATION_ERROR(-20010,

'Execute_system: Error while sending. Status = ' || status);

END IF;

status := DBMS_PIPE.RECEIVE_MESSAGE(pipe_name, timeout);

IF status <> 0 THEN

RAISE_APPLICATION_ERROR(-20011,

'Execute_system: Error while receiving.

Status = ' || status);

END IF;

/*获取返回结果*/

DBMS_PIPE.UNPACK_MESSAGE(result);

IF result <> 'done' THEN

RAISE_APPLICATION_ERROR(-20012,

'Execute_system: Done not received.');

END IF;

DBMS_PIPE.UNPACK_MESSAGE(command_code);

DBMS_OUTPUT.PUT_LINE('System command executed. result = ' ||

command_code);

RETURN command_code;

END execute_system;

/*stop是让daemon停止*/

PROCEDURE stop(timeout NUMBER DEFAULT 10) IS

status NUMBER;

BEGIN

DBMS_PIPE.PACK_MESSAGE('STOP');

status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout);

IF status <> 0 THEN

RAISE_APPLICATION_ERROR(-20030,

'stop: error while sending. status = ' || status);

END IF;

END stop;

END daemon;

通过Sql*Plus运行以上语句,将为当前用户创建daemon程序包.

2 创建在OS上运行的守护进程,监听由上面的daemon程序包发来的要求执行os命令的语句.以下Pro*C的代码,必须由pro*c先进行预编译.

#include

#include

EXEC SQL INCLUDE SQLCA;

EXEC SQL BEGIN DECLARE SECTION;

char *uid = "scott/tiger";/*在这个地方改为你自己访问的用户,密码,服务名*/

int status;

VARCHAR command[20];

VARCHAR value[2000];

VARCHAR return_name[30];

EXEC SQL END DECLARE SECTION;

void

connect_error()

{

char msg_buffer[512];

int msg_length;

int buffer_size = 512;

EXEC SQL WHENEVER SQLERROR CONTINUE;

sqlglm(msg_buffer, &buffer_size, &msg_length);

printf("Daemon error while connecting:/n");

printf("%.*s/n", msg_length, msg_buffer);

printf("Daemon quitting./n");

exit(1);

}

void

sql_error()

{

char msg_buffer[512];

int msg_length;

int buffer_size = 512;

EXEC SQL WHENEVER SQLERROR CONTINUE;

sqlglm(msg_buffer, &buffer_size, &msg_length);

printf("Daemon error while executing:/n");

printf("%.*s/n", msg_length, msg_buffer);

printf("Daemon continuing./n");

}

main()

{

EXEC SQL WHENEVER SQLERROR DO connect_error();

EXEC SQL CONNECT :uid;

printf("Daemon connected./n");

EXEC SQL WHENEVER SQLERROR DO sql_error();

printf("Daemon waiting.../n");

while (1) {

EXEC SQL EXECUTE

BEGIN

/*接收deamon发来的字符*/

:status := DBMS_PIPE.RECEIVE_MESSAGE('daemon');

IF :status = 0 THEN

/*取出字符*/

DBMS_PIPE.UNPACK_MESSAGE(:command);

END IF;

END;

END-EXEC;

IF (status == 0)

{

command.arr[command.len] = '/0';

/*如果是stop,该进程就退出*/

IF (!strcmp((char *) command.arr, "STOP"))

{

printf("Daemon exiting./n");

break;

}

ELSE IF (!strcmp((char *) command.arr, "SYSTEM"))

{

EXEC SQL EXECUTE

BEGIN

DBMS_PIPE.UNPACK_MESSAGE(:return_name);

DBMS_PIPE.UNPACK_MESSAGE(:value);

END;

END-EXEC;

value.arr[value.len] = '/0';

printf("Will execute system command '%s'/n", value.arr);

/*运行os命令*/

status = system(value.arr);

EXEC SQL EXECUTE

BEGIN

DBMS_PIPE.PACK_MESSAGE('done');

DBMS_PIPE.PACK_MESSAGE(:status);

:status := DBMS_PIPE.SEND_MESSAGE(:return_name);

END;

END-EXEC;

IF (status)

{

printf

("Daemon error while responding to system command.");

printf(" status: %d/n", status);

}

}

ELSE

{

printf

("Daemon error: invalid command '%s' received./n",

command.arr);

}

}

ELSE

{

printf("Daemon error while waiting for signal.");

printf(" status = %d/n", status);

}

}

EXEC SQL COMMIT WORK RELEASE;

exit(0);

}

以上代码起名为daemon.pc,用proc预编译:

proc iname=daemon.pc userid=用户名/密码@服务名 sqlcheck=semantics

得到daemon.c,在用c进行编译,注意在NT上要把orasql8.lib加上,否则编译通过,连接没法通过.

3 在服务器上运行daemon.exe

4 在sqlplus运行测试语句:

SQL> variable rv number

SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('ls -la');

PL/SQL 过程已成功完成。

SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('dir');

PL/SQL 过程已成功完成。

SQL>

DBMS_PIPE的用法见oracle的文档.