实验4

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

#include<fcntl.h>

#include<time.h>

#include<sys/types.h>

#include<unistd.h>

#include<sys/wait.h>

#include<syslog.h>

#include<signal.h> 

#include<sys/param.h> 

#include<sys/stat.h> 

int main()

{
FILE *fp;
pid_t child;
int i,lines,line,move;
char str[20],command[100];
child=fork();
if(child>0)
exit(0);
else if(child<0)
{
perror("创建子进程失败");
exit(1);
}
setsid();                 
chdir("/tmp");             
umask(0);                 
for(i=0;i< NOFILE;++i)   
close(i);
fp=fopen("ip.txt","r");
if(fp<=0)
{
perror("打开文件失败");
exit(1);
}
lines=0;
while(fscanf(fp,"%s",str)!=EOF)
{
lines++;
}
while(1)
{
fseek(fp,0,SEEK_SET);
srand((int)time(0));
line=rand()%lines+1;
move=0;
while(move<line)
{
fscanf(fp,"%s",str);
move++;
}
strcpy(command,"ifconfig eth0 ");
strcat(command,str);
strcat(command," netmask 255.255.255.0");
system(command);
sleep(8*60);
}
fclose(fp);

    return 0;

}