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[unix-history] / usr / src / usr.bin / users / users.c

/*
* Copyright (c) 1980, 1987 Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*/

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1980, 1987 Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)users.c     5.12 (Berkeley) %G%";
#endif /* not lint */

#include <sys/types.h>
#include <utmp.h>
#include <stdio.h>

#define MAXUSERS        200

main(argc, argv)
       int argc;
       char **argv;
{
       extern int optind;
       register int cnt, ncnt;
       struct utmp utmp;
       char names[MAXUSERS][UT_NAMESIZE];
       int ch, scmp();

       while ((ch = getopt(argc, argv, "")) != EOF)
               switch(ch) {
               case '?':
               default:
                       (void)fprintf(stderr, "usage: users\n");
                       exit(1);
               }
       argc -= optind;
       argv += optind;

       if (!freopen(_PATH_UTMP, "r", stdin)) {
               (void)fprintf(stderr, "users: can't open %s.\n", _PATH_UTMP);
               exit(1);
       }
       for (ncnt = 0;
           fread((char *)&utmp, sizeof(utmp), 1, stdin) == 1;)
               if (*utmp.ut_name) {
                       if (ncnt == MAXUSERS) {
                               (void)fprintf(stderr,
                                   "users: too many users.\n");
                               break;
                       }
                       (void)strncpy(names[ncnt], utmp.ut_name, UT_NAMESIZE);
                       ++ncnt;
               }

       if (ncnt) {
               qsort(names, ncnt, UT_NAMESIZE, scmp);
               (void)printf("%.*s", UT_NAMESIZE, names[0]);
               for (cnt = 1; cnt < ncnt; ++cnt)
                       if (strncmp(names[cnt], names[cnt - 1], UT_NAMESIZE))
                               (void)printf(" %.*s", UT_NAMESIZE, names[cnt]);
               (void)printf("\n");
       }
       exit(0);
}

scmp(p, q)
       char *p, *q;
{
       return(strncmp(p, q, UT_NAMESIZE));
}