src/date.c

   1 /* date - print or set the system date and time
   2    Copyright (C) 1989, 1991 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 2, or (at your option)
   7    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, write to the Free Software
  16    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  17
  18 /* Options:
  19    -d DATESTR   Display the date DATESTR.
  20    -s DATESTR   Set the date to DATESTR.
  21    -u           Display or set the date in universal instead of local time.
  22    +FORMAT      Specify custom date output format, described below.
  23    MMDDhhmm[[CC]YY][.ss]        Set the date in the format described below.
  24
  25    If one non-option argument is given, it is used as the date to which
  26    to set the system clock, and must have the format:
  27    MM   month (01..12)
  28    DD   day in month (01..31)
  29    hh   hour (00..23)
  30    mm   minute (00..59)
  31    CC   first 2 digits of year (optional, defaults to current) (00..99)
  32    YY   last 2 digits of year (optional, defaults to current) (00..99)
  33    ss   second (00..61)
  34
  35    If a non-option argument that starts with a `+' is specified, it
  36    is used to control the format in which the date is printed; it
  37    can contain any of the `%' substitutions allowed by the strftime
  38    function.  A newline is always added at the end of the output.
  39
  40    David MacKenzie <djm@gnu.ai.mit.edu> */
  41
  42 #ifdef HAVE_CONFIG_H
  43 #if defined (CONFIG_BROKETS)
  44 /* We use <config.h> instead of "config.h" so that a compilation
  45    using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
  46    (which it would do because it found this file in $srcdir).  */
  47 #include <config.h>
  48 #else
  49 #include "config.h"
  50 #endif
  51 #endif
  52
  53 #include <stdio.h>
  54 #include <getopt.h>
  55 #include <sys/types.h>
  56
  57 #include "version.h"
  58 #include "system.h"
  59
  60 #ifdef TM_IN_SYS_TIME
  61 #include <sys/time.h>
  62 #else
  63 #include <time.h>
  64 #endif
  65
  66 #ifndef STDC_HEADERS
  67 time_t mktime ();
  68 size_t strftime ();
  69 time_t time ();
  70 #endif
  71
  72 int putenv ();
  73 int stime ();
  74
  75 char *xrealloc ();
  76 time_t get_date ();
  77 time_t posixtime ();
  78 void error ();
  79
  80 static void show_date ();
  81 static void usage ();
  82
  83 /* putenv string to use Universal Coordinated Time.
  84    POSIX.2 says it should be "TZ=UCT0" or "TZ=GMT0". */
  85 #ifndef TZ_UCT
  86 #if defined(hpux) || defined(__hpux__) || defined(ultrix) || defined(__ultrix__) || defined(USG)
  87 #define TZ_UCT "TZ=GMT0"
  88 #else
  89 #define TZ_UCT "TZ="
  90 #endif
  91 #endif
  92
  93 /* The name this program was run with, for error messages. */
  94 char *program_name;
  95
  96 /* If non-zero, display usage information and exit.  */
  97 static int show_help;
  98
  99 /* If non-zero, print the version on standard output and exit.  */
 100 static int show_version;
 101
 102 static struct option const long_options[] =
 103 {
 104   {"date", required_argument, NULL, 'd'},
 105   {"help", no_argument, &show_help, 1},
 106   {"set", required_argument, NULL, 's'},
 107   {"uct", no_argument, NULL, 'u'},
 108   {"universal", no_argument, NULL, 'u'},
 109   {"version", no_argument, &show_version, 1},
 110   {NULL, 0, NULL, 0}
 111 };
 112
 113 void
 114 main (argc, argv)
 115      int argc;
 116      char **argv;
 117 {
 118   int optc;
 119   char *datestr = NULL;
 120   time_t when;
 121   int set_date = 0;
 122   int universal_time = 0;
 123
 124   program_name = argv[0];
 125
 126   while ((optc = getopt_long (argc, argv, "d:s:u", long_options, (int *) 0))
 127          != EOF)
 128     switch (optc)
 129       {
 130       case 0:
 131         break;
 132       case 'd':
 133         datestr = optarg;
 134         break;
 135       case 's':
 136         datestr = optarg;
 137         set_date = 1;
 138         break;
 139       case 'u':
 140         universal_time = 1;
 141         break;
 142       default:
 143         usage ();
 144       }
 145
 146   if (show_version)
 147     {
 148       printf ("%s\n", version_string);
 149       exit (0);
 150     }
 151
 152   if (show_help)
 153     usage ();
 154
 155   if (argc - optind > 1)
 156     usage ();
 157
 158   if (universal_time && putenv (TZ_UCT) != 0)
 159     error (1, 0, "virtual memory exhausted");
 160
 161   time (&when);
 162
 163   if (datestr)
 164     when = get_date (datestr, NULL);
 165
 166   if (argc - optind == 1 && argv[optind][0] != '+')
 167     {
 168       when = posixtime (argv[optind]);
 169       set_date = 1;
 170     }
 171
 172   if (when == -1)
 173     error (1, 0, "invalid date");
 174
 175   if (set_date && stime (&when) == -1)
 176     error (0, errno, "cannot set date");
 177
 178   if (argc - optind == 1 && argv[optind][0] == '+')
 179     show_date (argv[optind] + 1, when);
 180   else
 181     show_date ((char *) NULL, when);
 182
 183   exit (0);
 184 }
 185
 186 /* Display the date and/or time in WHEN according to the format specified
 187    in FORMAT, followed by a newline.  If FORMAT is NULL, use the
 188    standard output format (ctime style but with a timezone inserted). */
 189
 190 static void
 191 show_date (format, when)
 192      char *format;
 193      time_t when;
 194 {
 195   struct tm *tm;
 196   char *out = NULL;
 197   size_t out_length = 0;
 198
 199   tm = localtime (&when);
 200
 201   if (format == NULL)
 202     /* Print the date in the default format.  Vanilla ANSI C strftime
 203        doesn't support %e, but POSIX requires it.  If you don't use
 204        a GNU strftime, make sure yours supports %e.  */
 205     format = "%a %b %e %H:%M:%S %Z %Y";
 206   else if (*format == '\0')
 207     {
 208       printf ("\n");
 209       return;
 210     }
 211
 212   do
 213     {
 214       out_length += 200;
 215       out = (char *) xrealloc (out, out_length);
 216     }
 217   while (strftime (out, out_length, format, tm) == 0);
 218
 219   printf ("%s\n", out);
 220   free (out);
 221 }
 222
 223 static void
 224 usage ()
 225 {
 226   fprintf (stderr, "\
 227 Usage: %s [{--help,--version}] [-u] [-d datestr] [-s datestr]\n\
 228        [--date datestr] [--set datestr] [--uct] [--universal]\n\
 229        [+FORMAT] [MMDDhhmm[[CC]YY][.ss]]\n",
 230            program_name);
 231   exit (1);
 232 }