ipquery.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ndb.h>
#include <ip.h>

/*
 *  search the database for matches
 */

void
usage(void)
{
	fprint(2, "usage: ipquery attr value rattribute\n");
	exits("usage");
}

void
search(Ndb *db, char *attr, char *val, char **rattr, int nrattr)
{
	Ndbtuple *t, *tt;

	tt = ndbipinfo(db, attr, val, rattr, nrattr);
	for(t = tt; t; t = t->entry)
		print("%s=%s ", t->attr, t->val);
	print("\n");
	ndbfree(tt);
}

void
main(int argc, char **argv)
{
	Ndb *db;
	char *dbfile = 0;

	ARGBEGIN{
	case 'f':
		dbfile = ARGF();
		break;
	}ARGEND;

	if(argc < 3)
		usage();

	db = ndbopen(dbfile);
	if(db == 0){
		fprint(2, "no db files\n");
		exits("no db");
	}
	search(db, argv[0], argv[1], argv+2, argc-2);
	ndbclose(db);

	exits(0);
}