oracle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 ISstatus NUMBER;result VARCHAR2(20);command_code NUMBER;pipe_name VARCHAR2(30);BEGINpipe_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 THENRAISE_APPLICATION_ERROR(-20010,'Execute_system: Error while sending. Status = ' || status);END IF;status := DBMS_PIPE.RECEIVE_MESSAGE(pipe_name, timeout);IF status <> 0 THENRAISE_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' THENRAISE_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) ISstatus NUMBER;BEGINDBMS_PIPE.PACK_MESSAGE('STOP');status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout);IF status <> 0 THENRAISE_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;voidconnect_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);}voidsql_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 EXECUTEBEGIN/*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 EXECUTEBEGINDBMS_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 EXECUTEBEGINDBMS_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 numberSQL> 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.