[pipe] pipe streams to or from a process

Use pipe stream to process a file, then output the result.

Code

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

int main()
{
    FILE *read_fp;
    char buffer[BUFSIZ + 1];
    char macaddr_interface[18]={0};
    int chars_read;
    memset(buffer, '\0', sizeof(buffer));
    read_fp = popen("cat /home/happy/test/test100/Interface0.txt  | awk 'NR >1  {print $1;}'", "r");

    if (read_fp != NULL) {
        while (fscanf(read_fp, "%s", macaddr_interface) != EOF)
        {
            printf("macaddr_interface = %s \n",macaddr_interface);
        }

        pclose(read_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}

Test File

This file was called Interface0.txt

00:12:34:55:59:e7 192.168.0.2 0 Desktop
00:22:15:4f:40:4b 192.168.0.3 0 laptop
08:00:27:6d:d4:1a 192.168.0.4 0 good-00dbf1bd22
5c:ff:35:74:4c:5b 192.168.0.5 0 android-a6436da774239157
00:0c:29:3b:94:a4 192.168.0.6 0 PC1

Result

macaddr_interface = 00:22:15:4f:40:4b 
macaddr_interface = 08:00:27:6d:d4:1a 
macaddr_interface = 5c:ff:35:74:4c:5b 
macaddr_interface = 00:0c:29:3b:94:a4