#include <stdio.h>
#include <stdlib.h>  /* for atoi() */
#include <pwd.h>

int main(int argc, char **argv)
{
    if (argc < 2) {
	fprintf(stderr, "usage: %s uid ...\n", argv[0]);
	return(1);
    }

    for (argc--, argv++; argc > 0; argc--, argv++) {
	int uid = atoi(*argv);
	struct passwd *p = getpwuid(uid);
	if (p)
	    printf("uid %d is logname %s\n", uid, p->pw_name);
	else
	    printf("There is no entry in /etc/passwd for uid %d\n", uid);
    }

    return(0);
}