#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#define SZBUF 256

int main(int argc, char const *argv[])
{
	char buffer[SZBUF];
	int f0,f1,n,m;
	if (argc<3)
	{
		fprintf(stderr, "Usage: %s <SRC_FILE> <DEST_FILE>\n", argv[0]);
		exit(1);
	}
	fs = open(argv[1],O_RDONLY);
	if(fs==-1)
	{
		perror("Opening source file fails");
		exit(2);
	}
	fd=open(argv[2],O_WRONLY|O_TRONC|O_CREATE,0600);
	if(fd==-1)
	{
		perror("Opening destination file fails");
		exit(3);
	}
	while(n=read(fs,buffer,SZBUF))
	{
		m = write(fd,buffer,n)
		if(n==-1)
		{
			perror("writing in file fails");
			exit(4);
		}
	}
	close(fs);
	close(fd);
	exit(0);
}