shell c 混合编程 system 输出数据到变量

shell c 混合编程 system 输出数据到变量

方法一： （popen）

#include <stdio.h>
#include <stdlib.h>


int main( int argc, char *argv[] )
{

  FILE *fp;
  int status;
  char path[1035];

  /* Open the command for reading. */
  fp = popen("/bin/ls /etc/", "r");
  if (fp == NULL) {
    printf("Failed to run command\n" );
    exit;
  }

  /* Read the output a line at a time - output it. */
  while (fgets(path, sizeof(path)-1, fp) != NULL) {
    printf("%s", path);
  }

  /* close */
  pclose(fp);

  return 0;
}

方法二：

#include <stdio.h>
#include <stdlib.h>



static int my_system(const char* pCmd, char* pResult, int size)
{
    int fd[2];
    int pid;
    int count;
    int left;
    char* p = 0;
    int maxlen = size - 1;
    memset(pResult, 0, size);
    if(pipe(fd))
        {
            printf("pipe error\n");
            return -1;
        }
    if((pid = fork()) == 0)
        {// chile process
            int fd2[2];
            if(pipe(fd2))
                {
                    printf("pipe2 error\n");
                    return -1;
                }
            close(1);
            dup2(fd2[1],1);
            close(fd[0]);
            close(fd2[1]);
            system(pCmd);
            read(fd2[0], pResult, maxlen);
            pResult[strlen(pResult)-1] = 0;
            write(fd[1], pResult, strlen(pResult));
            close(fd2[0]);
            exit(0);
        }
    // parent process
    close(fd[1]);
    p = pResult;
    left = maxlen;
    while((count = read(fd[0], p, left))) {
        p = count;
        left -= count;
        if(left == 0)
            break;
    }
    close(fd[0]);
    return 0;
}
int main(void)
{
    char result[1025];
    my_system("LC_ALL=C ifconfig", result, 1025);
    printf("the result is\n\n%s\n", result);
    return 0;
}

完