popen()函数详解

popen()函数

 /*============================================
   > Copyright (C) 2014 All rights reserved.
   > FileName：popen.c
   > author：donald
   > date：2014/08/22/ 12:20:53
   > details：
 ==============================================*/
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #define N 512
 int main(int argc, const char *argv[])
 {
     FILE *fp;
     char cmd[N],buf[N];
     memset(cmd,,N);
     memset(buf,,N);
 #if 0
     fgets(cmd,N,stdin);
     fp = popen(cmd,"r");
     while(fgets(buf,N,fp) != NULL)
         printf("%s",buf);
 #endif
 #if 1
     fgets(cmd,N,stdin);
     fp = popen(cmd,"w");
     //这里把用户输入写进了cmd，
     if(fp == NULL)
         printf("error\n");
     fgets(buf,N,fp);
     printf("123%s\n",buf);//测试时使用
 #endif
     pclose(fp);
     return ;
 }

open_mode为“r”

open_mode为“w”

 /*============================================
 > Copyright (C) 2014 All rights reserved.
 > FileName：my_ponen.c
 > author：donald
 > details：
 ==============================================*/
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 int main(int argc, const char *argv[])
 {
 int left,right,sum;
 FILE* fp ;
 char cmd[] = "";
 while(){
 scanf("%d%d",&left,&right);
 sprintf(cmd,"%s %d %d",argv[],left,right);
 fp = popen(cmd,"r");
 fscanf(fp,"%d",&sum);
 printf("result is : %d\n",sum);

 pclose(fp);
 }
 return ;
 }

目标函数

 /*============================================
   > Copyright (C) 2014 All rights reserved.
   > FileName：mystring.c
   > author：donald
   > details：
 ==============================================*/
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #define N 1024
 int main(int argc, const char *argv[])
 {
     int index;
     char buf[N];
     memset(buf,,N);
     for(index = argc - ;index > ;index --){
         strcat(buf,argv[index]);
         strcat(buf," ");
     }
     printf("%s\n",buf);
     return ;
 }