C語言：popen函數(shù)的使用

C語?：popen函數(shù)的使?C語?：popen函數(shù)的使??、利?system函數(shù)調(diào)?shell命令，只能獲取到shell命令的返回值，?不能獲取shell命令的輸出結果，那如果想獲取輸出結果怎么辦呢？?popen函數(shù)可以實現(xiàn)。?、定義函數(shù)：FILE*popen(constchar*command,constchar*type);函數(shù)說明：popen()會調(diào)?fork()產(chǎn)??進程，然后從?進程中調(diào)?/bin/sh-c來執(zhí)?參數(shù)command的指令。參數(shù)type可使?"r"代表讀取，"w"代表寫?。依照此type值，popen()會建?管道連到?進程的標準輸出設備或標準輸?設備，然后返回?個?件指針。隨后進程便可利?此?件指針來讀取?進程的輸出設備或是寫?到?進程的標準輸?設備中。此外，所有使??件指針(FILE*)操作的函數(shù)也都可以使?，除了fclose()以外。返回值：若成功則返回?件指針,否則返回NULL,錯誤原因存于errno中.三、實例測試1、popen.c#include"stdio.h"#include"stdlib.h"intpopen_system(constchar*cmd,char*pRetMsg,intmsg_len){printf("\n\n________%s%dcmd=%s\n",__func__,__LINE__,cmd);FILE*fp;char*p=NULL;intres=-1;if(cmd==NULL||pRetMsg==NULL||msg_len<0){printf("ParamError!\n");return-1;}if((fp=popen(cmd,"r"))==NULL){printf("PopenError!\n");return-2;}else{memset(pRetMsg,0,msg_len);//getlastestresultwhile(fgets(pRetMsg,msg_len,fp)!=NULL){printf("Msg:%s",pRetMsg);//printallinfo}if((res=pclose(fp))==-1){printf("closepopenerror!\n");return-3;}//pRetMsg[strlen(pRetMsg)-1]='\0';pRetMsg[strlen(pRetMsg)]='\0';return0;}}}voidpopen_read(constchar*cmd){printf("\n\n________%s%dcmd=%s\n",__func__,__LINE__,cmd);FILE*fp;charbuf[200]={0};if((fp=popen(cmd,"r"))==NULL){perror("Failtopopen\n");exit(1);}while(fgets(buf,200,fp)!=NULL){printf("%s",buf);}pclose(fp);}voidpopen_write(constchar*cmd){printf("\n\n________%s%dcmd=%s\n",__func__,__LINE__,cmd);FILE*fp;charbuf[200]={0};if((fp=popen(cmd,"w"))==NULL){perror("Failtopopen\n");exit(1);}fwrite("Readpipesuccessfully!",1,sizeof("Readpipesuccessfully!"),fp);pclose(fp);}intmain(){char*cmd="who";chara8Result[128]={0};intret=0;inti=0;memset(a8Result,0,strlen(a8Result));ret=popen_system(cmd,a8Result,sizeof(a8Result));printf("ret=%da8Result=%slength=%d\n",ret,a8Result,strlen(a8Result));popen_read("./r