src/who.c

   1 /* GNU's who.
   2    Copyright (C) 1992-2023 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by jla; revised by djm; revised again by mstone */
  18
  19 /* Output format:
  20    name [state] line time [activity] [pid] [comment] [exit]
  21    state: -T
  22    name, line, time: not -q
  23    idle: -u
  24 */
  25
  26 #include <config.h>
  27 #include <getopt.h>
  28 #include <stdckdint.h>
  29 #include <stdio.h>
  30
  31 #include <sys/types.h>
  32 #include "system.h"
  33
  34 #include "c-ctype.h"
  35 #include "canon-host.h"
  36 #include "readutmp.h"
  37 #include "hard-locale.h"
  38 #include "quote.h"
  39
  40 #ifdef TTY_GROUP_NAME
  41 # include <grp.h>
  42 #endif
  43
  44 /* The official name of this program (e.g., no 'g' prefix).  */
  45 #define PROGRAM_NAME "who"
  46
  47 #define AUTHORS \
  48   proper_name ("Joseph Arceneaux"), \
  49   proper_name ("David MacKenzie"), \
  50   proper_name ("Michael Stone")
  51
  52 #ifdef RUN_LVL
  53 # define UT_TYPE_RUN_LVL(U) UT_TYPE_EQ (U, RUN_LVL)
  54 #else
  55 # define UT_TYPE_RUN_LVL(U) false
  56 #endif
  57
  58 #ifdef INIT_PROCESS
  59 # define UT_TYPE_INIT_PROCESS(U) UT_TYPE_EQ (U, INIT_PROCESS)
  60 #else
  61 # define UT_TYPE_INIT_PROCESS(U) false
  62 #endif
  63
  64 #ifdef LOGIN_PROCESS
  65 # define UT_TYPE_LOGIN_PROCESS(U) UT_TYPE_EQ (U, LOGIN_PROCESS)
  66 #else
  67 # define UT_TYPE_LOGIN_PROCESS(U) false
  68 #endif
  69
  70 #ifdef DEAD_PROCESS
  71 # define UT_TYPE_DEAD_PROCESS(U) UT_TYPE_EQ (U, DEAD_PROCESS)
  72 #else
  73 # define UT_TYPE_DEAD_PROCESS(U) false
  74 #endif
  75
  76 #ifdef NEW_TIME
  77 # define UT_TYPE_NEW_TIME(U) UT_TYPE_EQ (U, NEW_TIME)
  78 #else
  79 # define UT_TYPE_NEW_TIME(U) false
  80 #endif
  81
  82 #define IDLESTR_LEN 6
  83
  84 #if HAVE_STRUCT_XTMP_UT_PID
  85 # define PIDSTR_DECL_AND_INIT(Var, Utmp_ent) \
  86   char Var[INT_STRLEN_BOUND (Utmp_ent->ut_pid) + 1]; \
  87   sprintf (Var, "%ld", (long int) (Utmp_ent->ut_pid))
  88 #else
  89 # define PIDSTR_DECL_AND_INIT(Var, Utmp_ent) \
  90   char const *Var = ""
  91 #endif
  92
  93 #if HAVE_STRUCT_XTMP_UT_ID
  94 # define UT_ID(U) ((U)->ut_id)
  95 #else
  96 # define UT_ID(U) "??"
  97 #endif
  98
  99 /* If true, attempt to canonicalize hostnames via a DNS lookup. */
 100 static bool do_lookup;
 101
 102 /* If true, display only a list of usernames and count of
 103    the users logged on.
 104    Ignored for 'who am i'.  */
 105 static bool short_list;
 106
 107 /* If true, display only name, line, and time fields.  */
 108 static bool short_output;
 109
 110 /* If true, display the hours:minutes since each user has touched
 111    the keyboard, or "." if within the last minute, or "old" if
 112    not within the last day.  */
 113 static bool include_idle;
 114
 115 /* If true, display a line at the top describing each field.  */
 116 static bool include_heading;
 117
 118 /* If true, display a '+' for each user if mesg y, a '-' if mesg n,
 119    or a '?' if their tty cannot be statted. */
 120 static bool include_mesg;
 121
 122 /* If true, display process termination & exit status.  */
 123 static bool include_exit;
 124
 125 /* If true, display the last boot time.  */
 126 static bool need_boottime;
 127
 128 /* If true, display dead processes.  */
 129 static bool need_deadprocs;
 130
 131 /* If true, display processes waiting for user login.  */
 132 static bool need_login;
 133
 134 /* If true, display processes started by init.  */
 135 static bool need_initspawn;
 136
 137 /* If true, display the last clock change.  */
 138 static bool need_clockchange;
 139
 140 /* If true, display the current runlevel.  */
 141 static bool need_runlevel;
 142
 143 /* If true, display user processes.  */
 144 static bool need_users;
 145
 146 /* If true, display info only for the controlling tty.  */
 147 static bool my_line_only;
 148
 149 /* The strftime format to use for login times, and its expected
 150    output width.  */
 151 static char const *time_format;
 152 static int time_format_width;
 153
 154 /* for long options with no corresponding short option, use enum */
 155 enum
 156 {
 157   LOOKUP_OPTION = CHAR_MAX + 1
 158 };
 159
 160 static struct option const longopts[] =
 161 {
 162   {"all", no_argument, nullptr, 'a'},
 163   {"boot", no_argument, nullptr, 'b'},
 164   {"count", no_argument, nullptr, 'q'},
 165   {"dead", no_argument, nullptr, 'd'},
 166   {"heading", no_argument, nullptr, 'H'},
 167   {"login", no_argument, nullptr, 'l'},
 168   {"lookup", no_argument, nullptr, LOOKUP_OPTION},
 169   {"message", no_argument, nullptr, 'T'},
 170   {"mesg", no_argument, nullptr, 'T'},
 171   {"process", no_argument, nullptr, 'p'},
 172   {"runlevel", no_argument, nullptr, 'r'},
 173   {"short", no_argument, nullptr, 's'},
 174   {"time", no_argument, nullptr, 't'},
 175   {"users", no_argument, nullptr, 'u'},
 176   {"writable", no_argument, nullptr, 'T'},
 177   {GETOPT_HELP_OPTION_DECL},
 178   {GETOPT_VERSION_OPTION_DECL},
 179   {nullptr, 0, nullptr, 0}
 180 };
 181
 182 /* Return a string representing the time between WHEN and now.
 183    BOOTTIME is the time of last reboot.
 184    FIXME: locale? */
 185 static char const *
 186 idle_string (time_t when, time_t boottime)
 187 {
 188   static time_t now = TYPE_MINIMUM (time_t);
 189
 190   if (now == TYPE_MINIMUM (time_t))
 191     time (&now);
 192
 193   int seconds_idle;
 194   if (boottime < when && when <= now
 195       && ! ckd_sub (&seconds_idle, now, when)
 196       && seconds_idle < 24 * 60 * 60)
 197     {
 198       if (seconds_idle < 60)
 199         return "  .  ";
 200       else
 201         {
 202           static char idle_hhmm[IDLESTR_LEN];
 203           sprintf (idle_hhmm, "%02d:%02d",
 204                    seconds_idle / (60 * 60),
 205                    (seconds_idle % (60 * 60)) / 60);
 206           return idle_hhmm;
 207         }
 208     }
 209
 210   return _(" old ");
 211 }
 212
 213 /* Return a time string.  */
 214 static char const *
 215 time_string (const STRUCT_UTMP *utmp_ent)
 216 {
 217   static char buf[INT_STRLEN_BOUND (intmax_t) + sizeof "-%m-%d %H:%M"];
 218
 219   /* Don't take the address of UT_TIME_MEMBER directly.
 220      Ulrich Drepper wrote:
 221      "... GNU libc (and perhaps other libcs as well) have extended
 222      utmp file formats which do not use a simple time_t ut_time field.
 223      In glibc, ut_time is a macro which selects for backward compatibility
 224      the tv_sec member of a struct timeval value."  */
 225   time_t t = UT_TIME_MEMBER (utmp_ent);
 226   struct tm *tmp = localtime (&t);
 227
 228   if (tmp)
 229     {
 230       strftime (buf, sizeof buf, time_format, tmp);
 231       return buf;
 232     }
 233   else
 234     return timetostr (t, buf);
 235 }
 236
 237 /* Print formatted output line. Uses mostly arbitrary field sizes, probably
 238    will need tweaking if any of the localization stuff is done, or for 64 bit
 239    pids, etc. */
 240 static void
 241 print_line (int userlen, char const *user, const char state,
 242             int linelen, char const *line,
 243             char const *time_str, char const *idle, char const *pid,
 244             char const *comment, char const *exitstr)
 245 {
 246   static char mesg[3] = { ' ', 'x', '\0' };
 247   char *buf;
 248   char x_idle[1 + IDLESTR_LEN + 1];
 249   char x_pid[1 + INT_STRLEN_BOUND (pid_t) + 1];
 250   char *x_exitstr;
 251   int err;
 252
 253   mesg[1] = state;
 254
 255   if (include_idle && !short_output && strlen (idle) < sizeof x_idle - 1)
 256     sprintf (x_idle, " %-6s", idle);
 257   else
 258     *x_idle = '\0';
 259
 260   if (!short_output && strlen (pid) < sizeof x_pid - 1)
 261     sprintf (x_pid, " %10s", pid);
 262   else
 263     *x_pid = '\0';
 264
 265   x_exitstr = xmalloc (include_exit ? 1 + MAX (12, strlen (exitstr)) + 1 : 1);
 266   if (include_exit)
 267     sprintf (x_exitstr, " %-12s", exitstr);
 268   else
 269     *x_exitstr = '\0';
 270
 271   err = asprintf (&buf,
 272                   "%-8.*s"
 273                   "%s"
 274                   " %-12.*s"
 275                   " %-*s"
 276                   "%s"
 277                   "%s"
 278                   " %-8s"
 279                   "%s"
 280                   ,
 281                   userlen, user ? user : "   .",
 282                   include_mesg ? mesg : "",
 283                   linelen, line,
 284                   time_format_width,
 285                   time_str,
 286                   x_idle,
 287                   x_pid,
 288                   /* FIXME: it's not really clear whether the following
 289                      field should be in the short_output.  A strict reading
 290                      of SUSv2 would suggest not, but I haven't seen any
 291                      implementations that actually work that way... */
 292                   comment,
 293                   x_exitstr
 294                   );
 295   if (err == -1)
 296     xalloc_die ();
 297
 298   {
 299     /* Remove any trailing spaces.  */
 300     char *p = buf + strlen (buf);
 301     while (*--p == ' ')
 302       /* empty */;
 303     *(p + 1) = '\0';
 304   }
 305
 306   puts (buf);
 307   free (buf);
 308   free (x_exitstr);
 309 }
 310
 311 /* Return true if a terminal device given as PSTAT allows other users
 312    to send messages to; false otherwise */
 313 static bool
 314 is_tty_writable (struct stat const *pstat)
 315 {
 316 #ifdef TTY_GROUP_NAME
 317   /* Ensure the group of the TTY device matches TTY_GROUP_NAME, more info at
 318      https://bugzilla.redhat.com/454261 */
 319   struct group *ttygr = getgrnam (TTY_GROUP_NAME);
 320   if (!ttygr || (pstat->st_gid != ttygr->gr_gid))
 321     return false;
 322 #endif
 323
 324   return pstat->st_mode & S_IWGRP;
 325 }
 326
 327 /* Send properly parsed USER_PROCESS info to print_line.  The most
 328    recent boot time is BOOTTIME. */
 329 static void
 330 print_user (const STRUCT_UTMP *utmp_ent, time_t boottime)
 331 {
 332   struct stat stats;
 333   time_t last_change;
 334   char mesg;
 335   char idlestr[IDLESTR_LEN + 1];
 336   static char *hoststr;
 337 #if HAVE_UT_HOST
 338   static size_t hostlen;
 339 #endif
 340
 341 #define DEV_DIR_WITH_TRAILING_SLASH "/dev/"
 342 #define DEV_DIR_LEN (sizeof (DEV_DIR_WITH_TRAILING_SLASH) - 1)
 343
 344   char line[sizeof (utmp_ent->ut_line) + DEV_DIR_LEN + 1];
 345   char *p = line;
 346   PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);
 347
 348   /* Copy ut_line into LINE, prepending '/dev/' if ut_line is not
 349      already an absolute file name.  Some systems may put the full,
 350      absolute file name in ut_line.  */
 351   if ( ! IS_ABSOLUTE_FILE_NAME (utmp_ent->ut_line))
 352     p = stpcpy (p, DEV_DIR_WITH_TRAILING_SLASH);
 353   stzncpy (p, utmp_ent->ut_line, sizeof (utmp_ent->ut_line));
 354
 355   if (stat (line, &stats) == 0)
 356     {
 357       mesg = is_tty_writable (&stats) ? '+' : '-';
 358       last_change = stats.st_atime;
 359     }
 360   else
 361     {
 362       mesg = '?';
 363       last_change = 0;
 364     }
 365
 366   if (last_change)
 367     sprintf (idlestr, "%.*s", IDLESTR_LEN, idle_string (last_change, boottime));
 368   else
 369     sprintf (idlestr, "  ?");
 370
 371 #if HAVE_UT_HOST
 372   if (utmp_ent->ut_host[0])
 373     {
 374       char ut_host[sizeof (utmp_ent->ut_host) + 1];
 375       char *host = nullptr;
 376       char *display = nullptr;
 377
 378       /* Copy the host name into UT_HOST, and ensure it's nul terminated. */
 379       stzncpy (ut_host, utmp_ent->ut_host, sizeof (utmp_ent->ut_host));
 380
 381       /* Look for an X display.  */
 382       display = strchr (ut_host, ':');
 383       if (display)
 384         *display++ = '\0';
 385
 386       if (*ut_host && do_lookup)
 387         {
 388           /* See if we can canonicalize it.  */
 389           host = canon_host (ut_host);
 390         }
 391
 392       if (! host)
 393         host = ut_host;
 394
 395       if (display)
 396         {
 397           if (hostlen < strlen (host) + strlen (display) + 4)
 398             {
 399               hostlen = strlen (host) + strlen (display) + 4;
 400               free (hoststr);
 401               hoststr = xmalloc (hostlen);
 402             }
 403           sprintf (hoststr, "(%s:%s)", host, display);
 404         }
 405       else
 406         {
 407           if (hostlen < strlen (host) + 3)
 408             {
 409               hostlen = strlen (host) + 3;
 410               free (hoststr);
 411               hoststr = xmalloc (hostlen);
 412             }
 413           sprintf (hoststr, "(%s)", host);
 414         }
 415
 416       if (host != ut_host)
 417         free (host);
 418     }
 419   else
 420     {
 421       if (hostlen < 1)
 422         {
 423           hostlen = 1;
 424           free (hoststr);
 425           hoststr = xmalloc (hostlen);
 426         }
 427       *hoststr = '\0';
 428     }
 429 #endif
 430
 431   print_line (sizeof UT_USER (utmp_ent), UT_USER (utmp_ent), mesg,
 432               sizeof utmp_ent->ut_line, utmp_ent->ut_line,
 433               time_string (utmp_ent), idlestr, pidstr,
 434               hoststr ? hoststr : "", "");
 435 }
 436
 437 static void
 438 print_boottime (const STRUCT_UTMP *utmp_ent)
 439 {
 440   print_line (-1, "", ' ', -1, _("system boot"),
 441               time_string (utmp_ent), "", "", "", "");
 442 }
 443
 444 static char *
 445 make_id_equals_comment (STRUCT_UTMP const *utmp_ent)
 446 {
 447   size_t utmpsize = sizeof UT_ID (utmp_ent);
 448   char *comment = xmalloc (strlen (_("id=")) + utmpsize + 1);
 449
 450   char *p = stpcpy (comment, _("id="));
 451   stzncpy (p, UT_ID (utmp_ent), utmpsize);
 452   return comment;
 453 }
 454
 455 static void
 456 print_deadprocs (const STRUCT_UTMP *utmp_ent)
 457 {
 458   static char *exitstr;
 459   char *comment = make_id_equals_comment (utmp_ent);
 460   PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);
 461
 462   if (!exitstr)
 463     exitstr = xmalloc (strlen (_("term="))
 464                        + INT_STRLEN_BOUND (UT_EXIT_E_TERMINATION (utmp_ent)) + 1
 465                        + strlen (_("exit="))
 466                        + INT_STRLEN_BOUND (UT_EXIT_E_EXIT (utmp_ent))
 467                        + 1);
 468   sprintf (exitstr, "%s%d %s%d", _("term="), UT_EXIT_E_TERMINATION (utmp_ent),
 469            _("exit="), UT_EXIT_E_EXIT (utmp_ent));
 470
 471   /* FIXME: add idle time? */
 472
 473   print_line (-1, "", ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
 474               time_string (utmp_ent), "", pidstr, comment, exitstr);
 475   free (comment);
 476 }
 477
 478 static void
 479 print_login (const STRUCT_UTMP *utmp_ent)
 480 {
 481   char *comment = make_id_equals_comment (utmp_ent);
 482   PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);
 483
 484   /* FIXME: add idle time? */
 485
 486   print_line (-1, _("LOGIN"), ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
 487               time_string (utmp_ent), "", pidstr, comment, "");
 488   free (comment);
 489 }
 490
 491 static void
 492 print_initspawn (const STRUCT_UTMP *utmp_ent)
 493 {
 494   char *comment = make_id_equals_comment (utmp_ent);
 495   PIDSTR_DECL_AND_INIT (pidstr, utmp_ent);
 496
 497   print_line (-1, "", ' ', sizeof utmp_ent->ut_line, utmp_ent->ut_line,
 498               time_string (utmp_ent), "", pidstr, comment, "");
 499   free (comment);
 500 }
 501
 502 static void
 503 print_clockchange (const STRUCT_UTMP *utmp_ent)
 504 {
 505   /* FIXME: handle NEW_TIME & OLD_TIME both */
 506   print_line (-1, "", ' ', -1, _("clock change"),
 507               time_string (utmp_ent), "", "", "", "");
 508 }
 509
 510 static void
 511 print_runlevel (const STRUCT_UTMP *utmp_ent)
 512 {
 513   static char *runlevline, *comment;
 514   unsigned char last = UT_PID (utmp_ent) / 256;
 515   unsigned char curr = UT_PID (utmp_ent) % 256;
 516
 517   if (!runlevline)
 518     runlevline = xmalloc (strlen (_("run-level")) + 3);
 519   sprintf (runlevline, "%s %c", _("run-level"), curr);
 520
 521   if (!comment)
 522     comment = xmalloc (strlen (_("last=")) + 2);
 523   sprintf (comment, "%s%c", _("last="), (last == 'N') ? 'S' : last);
 524
 525   print_line (-1, "", ' ', -1, runlevline, time_string (utmp_ent),
 526               "", "", c_isprint (last) ? comment : "", "");
 527
 528   return;
 529 }
 530
 531 /* Print the username of each valid entry and the number of valid entries
 532    in UTMP_BUF, which should have N elements. */
 533 static void
 534 list_entries_who (size_t n, const STRUCT_UTMP *utmp_buf)
 535 {
 536   unsigned long int entries = 0;
 537   char const *separator = "";
 538
 539   while (n--)
 540     {
 541       if (IS_USER_PROCESS (utmp_buf))
 542         {
 543           char *trimmed_name;
 544
 545           trimmed_name = extract_trimmed_name (utmp_buf);
 546
 547           printf ("%s%s", separator, trimmed_name);
 548           free (trimmed_name);
 549           separator = " ";
 550           entries++;
 551         }
 552       utmp_buf++;
 553     }
 554   printf (_("\n# users=%lu\n"), entries);
 555 }
 556
 557 static void
 558 print_heading (void)
 559 {
 560   print_line (-1, _("NAME"), ' ', -1, _("LINE"), _("TIME"), _("IDLE"),
 561               _("PID"), _("COMMENT"), _("EXIT"));
 562 }
 563
 564 /* Display UTMP_BUF, which should have N entries. */
 565 static void
 566 scan_entries (size_t n, const STRUCT_UTMP *utmp_buf)
 567 {
 568   char *ttyname_b IF_LINT ( = nullptr);
 569   time_t boottime = TYPE_MINIMUM (time_t);
 570
 571   if (include_heading)
 572     print_heading ();
 573
 574   if (my_line_only)
 575     {
 576       ttyname_b = ttyname (STDIN_FILENO);
 577       if (!ttyname_b)
 578         return;
 579       if (STRNCMP_LIT (ttyname_b, DEV_DIR_WITH_TRAILING_SLASH) == 0)
 580         ttyname_b += DEV_DIR_LEN;       /* Discard /dev/ prefix.  */
 581     }
 582
 583   while (n--)
 584     {
 585       if (!my_line_only
 586           || STREQ_LEN (ttyname_b, utmp_buf->ut_line,
 587                         sizeof (utmp_buf->ut_line)))
 588         {
 589           if (need_users && IS_USER_PROCESS (utmp_buf))
 590             print_user (utmp_buf, boottime);
 591           else if (need_runlevel && UT_TYPE_RUN_LVL (utmp_buf))
 592             print_runlevel (utmp_buf);
 593           else if (need_boottime && UT_TYPE_BOOT_TIME (utmp_buf))
 594             print_boottime (utmp_buf);
 595           /* I've never seen one of these, so I don't know what it should
 596              look like :^)
 597              FIXME: handle OLD_TIME also, perhaps show the delta? */
 598           else if (need_clockchange && UT_TYPE_NEW_TIME (utmp_buf))
 599             print_clockchange (utmp_buf);
 600           else if (need_initspawn && UT_TYPE_INIT_PROCESS (utmp_buf))
 601             print_initspawn (utmp_buf);
 602           else if (need_login && UT_TYPE_LOGIN_PROCESS (utmp_buf))
 603             print_login (utmp_buf);
 604           else if (need_deadprocs && UT_TYPE_DEAD_PROCESS (utmp_buf))
 605             print_deadprocs (utmp_buf);
 606         }
 607
 608       if (UT_TYPE_BOOT_TIME (utmp_buf))
 609         boottime = UT_TIME_MEMBER (utmp_buf);
 610
 611       utmp_buf++;
 612     }
 613 }
 614
 615 /* Display a list of who is on the system, according to utmp file FILENAME.
 616    Use read_utmp OPTIONS to read the file.  */
 617 static void
 618 who (char const *filename, int options)
 619 {
 620   size_t n_users;
 621   STRUCT_UTMP *utmp_buf;
 622
 623   if (read_utmp (filename, &n_users, &utmp_buf, options) != 0)
 624     error (EXIT_FAILURE, errno, "%s", quotef (filename));
 625
 626   if (short_list)
 627     list_entries_who (n_users, utmp_buf);
 628   else
 629     scan_entries (n_users, utmp_buf);
 630
 631   free (utmp_buf);
 632 }
 633
 634 void
 635 usage (int status)
 636 {
 637   if (status != EXIT_SUCCESS)
 638     emit_try_help ();
 639   else
 640     {
 641       printf (_("Usage: %s [OPTION]... [ FILE | ARG1 ARG2 ]\n"), program_name);
 642       fputs (_("\
 643 Print information about users who are currently logged in.\n\
 644 "), stdout);
 645       fputs (_("\
 646 \n\
 647   -a, --all         same as -b -d --login -p -r -t -T -u\n\
 648   -b, --boot        time of last system boot\n\
 649   -d, --dead        print dead processes\n\
 650   -H, --heading     print line of column headings\n\
 651 "), stdout);
 652       fputs (_("\
 653   -l, --login       print system login processes\n\
 654 "), stdout);
 655       fputs (_("\
 656       --lookup      attempt to canonicalize hostnames via DNS\n\
 657   -m                only hostname and user associated with stdin\n\
 658   -p, --process     print active processes spawned by init\n\
 659 "), stdout);
 660       fputs (_("\
 661   -q, --count       all login names and number of users logged on\n\
 662   -r, --runlevel    print current runlevel\n\
 663   -s, --short       print only name, line, and time (default)\n\
 664   -t, --time        print last system clock change\n\
 665 "), stdout);
 666       fputs (_("\
 667   -T, -w, --mesg    add user's message status as +, - or ?\n\
 668   -u, --users       list users logged in\n\
 669       --message     same as -T\n\
 670       --writable    same as -T\n\
 671 "), stdout);
 672       fputs (HELP_OPTION_DESCRIPTION, stdout);
 673       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 674       printf (_("\
 675 \n\
 676 If FILE is not specified, use %s.  %s as FILE is common.\n\
 677 If ARG1 ARG2 given, -m presumed: 'am i' or 'mom likes' are usual.\n\
 678 "), UTMP_FILE, WTMP_FILE);
 679       emit_ancillary_info (PROGRAM_NAME);
 680     }
 681   exit (status);
 682 }
 683
 684 int
 685 main (int argc, char **argv)
 686 {
 687   int optc;
 688   bool assumptions = true;
 689
 690   initialize_main (&argc, &argv);
 691   set_program_name (argv[0]);
 692   setlocale (LC_ALL, "");
 693   bindtextdomain (PACKAGE, LOCALEDIR);
 694   textdomain (PACKAGE);
 695
 696   atexit (close_stdout);
 697
 698   while ((optc = getopt_long (argc, argv, "abdlmpqrstuwHT", longopts, nullptr))
 699          != -1)
 700     {
 701       switch (optc)
 702         {
 703         case 'a':
 704           need_boottime = true;
 705           need_deadprocs = true;
 706           need_login = true;
 707           need_initspawn = true;
 708           need_runlevel = true;
 709           need_clockchange = true;
 710           need_users = true;
 711           include_mesg = true;
 712           include_idle = true;
 713           include_exit = true;
 714           assumptions = false;
 715           break;
 716
 717         case 'b':
 718           need_boottime = true;
 719           assumptions = false;
 720           break;
 721
 722         case 'd':
 723           need_deadprocs = true;
 724           include_idle = true;
 725           include_exit = true;
 726           assumptions = false;
 727           break;
 728
 729         case 'H':
 730           include_heading = true;
 731           break;
 732
 733         case 'l':
 734           need_login = true;
 735           include_idle = true;
 736           assumptions = false;
 737           break;
 738
 739         case 'm':
 740           my_line_only = true;
 741           break;
 742
 743         case 'p':
 744           need_initspawn = true;
 745           assumptions = false;
 746           break;
 747
 748         case 'q':
 749           short_list = true;
 750           break;
 751
 752         case 'r':
 753           need_runlevel = true;
 754           include_idle = true;
 755           assumptions = false;
 756           break;
 757
 758         case 's':
 759           short_output = true;
 760           break;
 761
 762         case 't':
 763           need_clockchange = true;
 764           assumptions = false;
 765           break;
 766
 767         case 'T':
 768         case 'w':
 769           include_mesg = true;
 770           break;
 771
 772         case 'u':
 773           need_users = true;
 774           include_idle = true;
 775           assumptions = false;
 776           break;
 777
 778         case LOOKUP_OPTION:
 779           do_lookup = true;
 780           break;
 781
 782         case_GETOPT_HELP_CHAR;
 783
 784         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
 785
 786         default:
 787           usage (EXIT_FAILURE);
 788         }
 789     }
 790
 791   if (assumptions)
 792     {
 793       need_users = true;
 794       short_output = true;
 795     }
 796
 797   if (include_exit)
 798     {
 799       short_output = false;
 800     }
 801
 802   if (hard_locale (LC_TIME))
 803     {
 804       time_format = "%Y-%m-%d %H:%M";
 805       time_format_width = 4 + 1 + 2 + 1 + 2 + 1 + 2 + 1 + 2;
 806     }
 807   else
 808     {
 809       time_format = "%b %e %H:%M";
 810       time_format_width = 3 + 1 + 2 + 1 + 2 + 1 + 2;
 811     }
 812
 813   switch (argc - optind)
 814     {
 815     case 2:                     /* who <blurf> <glop> */
 816       my_line_only = true;
 817       FALLTHROUGH;
 818     case -1:
 819     case 0:                     /* who */
 820       who (UTMP_FILE, READ_UTMP_CHECK_PIDS);
 821       break;
 822
 823     case 1:                     /* who <utmp file> */
 824       who (argv[optind], 0);
 825       break;
 826
 827     default:                    /* lose */
 828       error (0, 0, _("extra operand %s"), quote (argv[optind + 2]));
 829       usage (EXIT_FAILURE);
 830     }
 831
 832   return EXIT_SUCCESS;
 833 }