进程
1.进程的命令
查看CPU：top
查看所有的进程：ps -A
查看当前的进程：ps
关闭进程：kill -9 进程id
int main(int argc, char *argv[])
{
char caFile[64] = {'\\0'};
strncpy(caFile, argv[1], sizeof(caFile));
int ret = -1;
strcat(caFile, ".old");
ret = rename(argv[1], caFile);
if (-1 == ret)
{
printf("rename error:%s\\n", strerror(errno));
return -1;
}
int fdNew = -1;
fdNew = open(argv[1], O_WRONLY | O_CREAT
, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (-1 == fdNew)
{
printf("open error:%s\\n", strerror(errno));
return -1;
}
int fdOld = -1;
fdOld = open(caFile, O_RDONLY);
if (-1 == fdOld)
{
printf("open error:%s\\n", strerror(errno));
return -1;
}
off_t offset = 0;
printf("please input position:");
scanf("%ld", &offset);
char caBuf[PER_IO_BYTES] = {'\\0'};
int iLeft = offset;
//将指定位置之前的数据拷贝到新文件中
while (iLeft)
{
if (iLeft >= PER_IO_BYTES)
{
ret = read(fdOld, caBuf, PER_IO_BYTES);
}
else
{
ret = read(fdOld, caBuf, iLeft);
}
if (-1 == ret)
{
printf("read error:%s\\n", strerror(errno));
break;
}
iLeft -= ret;
ret = write(fdNew, caBuf, ret);
if (-1 == ret)
{
printf("write error:%s\\n", strerror(errno));
break;
}
}
//在指定的位置写入数据
char *pData = "$$$qwertyuiopasdfghjklzxcvbnm$$$";
ret = write(fdNew, pData, strlen(pData));
if (-1 == ret)
{
printf("write error:%s\\n", strerror(errno));
return;
}
//将指定位置之后的数据写入新文件中
while (1)
{
ret = read(fdOld, caBuf, PER_IO_BYTES);
if (-1 == ret)
{
printf("read error:%s\\n", strerror(errno));
break;
}
else if (0 == ret)
{
break;
}
ret = write(fdNew, caBuf, ret);
if (-1 == ret)
{
printf("write error:%s\\n", strerror(errno));
break;
}
}
close(fdNew);
close(fdOld);
ret = remove(caFile);
if (-1 == ret)
{
printf("remove error:%s\\n", strerror(errno));
return -1;
}
return 0;
}
