Question

linux怎么绕开文件系统缓存?

Answer 1

无法绕开的。
文件系统缓存是内核自动控制的。
其他的方法没有试过了，你可以自己百度看看

Answer 2

#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<stdio.h>
#include<errno.h>
#include<stdlib.h>

#define BUFFER_SIZE 1024

int main(int argc,char *argv[])
{
int from_fd,to_fd;
int bytes_read,bytes_write;
char buffer[BUFFER_SIZE];
char *ptr;

if(argc!= 3)
{
fprintf(stderr,"Usage:%s fromfile tofile/n/a",argv[0]);
exit(1);
}

if((from_fd = open(argv[1],O_RDONLY))==-1)
{
fprintf(stderr,"Open %s ERROR:%s/n",argv[1],strerror(errno));
exit(1);
}

if((to_fd = open(argv[2],O_WRONLY|O_CREAT,755))==-1)
{
fprintf(stderr,"Open %s Error:%s/n",argv[2],strerror(errno));
exit(1);
}

while(bytes_read = read(from_fd,buffer,BUFFER_SIZE))
{
if((bytes_read == -1)&&(errno!=EINTR)) break;
else if(bytes_read >0)
{
ptr = buffer;
while(bytes_write = write(to_fd,ptr,bytes_read))
{
if((bytes_write==-1)&&(errno!=EINTR))break;

else if(bytes_write == bytes_read) break;

else if(bytes_write > 0)
{
ptr+=bytes_write;
bytes_read-=bytes_write;
}
}

if(bytes_write == -1)break;
}
}

close(from_fd);
close(to_fd);
exit(0);
}