rename.c

This is to bulid a sample linux shell.

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

int main(int argc,char *argv[])
{
	if(argc != 3)
	{
		printf("daemon: Insufficient or Extra Arguments.\n ");
		return 0;
	}
	FILE *fp;
	char ch;
	fp=fopen(argv[2],"r");
	if(fp!=NULL)
	{
		printf("daemon: Overwrite %s [y/n]? ",argv[2]);
		scanf("%c",&ch);
		fclose(fp);
		if(ch=='n'||ch=='N')
			return 0;
		unlink(argv[2]);
	}
	if(link(argv[1],argv[2]) == 0)
		return(unlink(argv[1]));
	else
		printf("daemon: %s file not found.\n",argv[1]);
	return -1;
}