08.linux的编程：进程间通信：管道

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1、8.Linux的编程：进程间通信：管道例1：管道的打开和关闭函数定义#includeintpipe(intfiledes[2]);功能：fildes为两个元素的整形数组，pipe调用产生一个管道，管道的读描述符存入fildes[0]，管道的写描述符存入fildes[1]。一个进程可以向fildes[1]中写入数据，另一个进程可以从fildes[0]中读出数据。Close可以关闭管道源程序/**opipe.c-Openandcloseapipe*/#include#include#include<

2、stdlib.h>intmain(void){intfd[2];/*Arrayforfiledescriptors*/if((pipe(fd))<0){perror("pipe");exit(EXIT_FAILURE);}printf("descriptorsare%d,%d",fd[0],fd[1]);close(fd[0]);close(fd[1]);exit(EXIT_SUCCESS);}例2：读写管道用read,write调用读写管道/**piperw.c-Thecorrectwaytoopenapipeandfork*achildproc

3、ess.*/#include#include#include#include#include#include#include#defineBUFSZPIPE_BUFvoiderr_quit(char*msg);intmain(intargc,char*argv[]){intfd[2];/*Filedescriptorarrayforthepipe*/intfdin;/*Descriptorforinputfi

4、le*/charbuf[BUFSZ];intpid,len;/*Createthepipe*/if((pipe(fd))<0)err_quit("pipe");/*Forkandclosetheappropriatedescriptors*/if((pid=fork())<0)err_quit("fork");if(pid==0){/*Childisreader,closethewritedescriptor*/close(fd[1]);while((len=read(fd[0],buf,BUFSZ))>0)write(STDOUT_FILENO,bu

5、f,len);close(fd[0]);}else{/*Parentiswriter,closethereaddescriptor*/close(fd[0]);if((fdin=open(argv[1],O_RDONLY))<0){perror("open");/*Sendsomethingsincewecouldn'topentheinput*/write(fd[1],"123",4);}else{while((len=read(fdin,buf,BUFSZ))>0)write(fd[1],buf,len);close(fdin);}/*Clos

6、ethewritedescriptor*/close(fd[1]);}/*Reaptheexitstatus*/waitpid(pid,NULL,0);exit(EXIT_SUCCESS);}voiderr_quit(char*msg){perror(msg);exit(EXIT_FAILURE);}执行结果：例3：更简单的父子进程管道通信相关函数#includeFILE*popen(constchar*command,constchar*mode);功能：创建一个管道，再创建一个进程执行command，之后根据mode指定的是读还是

7、写，返回管道的文件句柄intpclose(FILE*stream);功能：关闭stream对应的管道，等待通过stream与自己通信的进程的结束。源程序/**popen.c-Usingpopen()toopenapipe*/#include#include#include#include#include#defineBUFSZPIPE_BUFvoiderr_quit(char*msg);intmain(void){FILE*fp;/*FILEstreamfo

8、rpopen*/char*cmdstring="catpopen.c";charbuf[BUF