date.c

此程序为LINUX 日期控制程序,希望对需要的朋友有所帮助

/* date - print or set the system date and time
   Copyright (C) 1989-2002 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   David MacKenzie <[e-mail]> */

#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
#if HAVE_LANGINFO_CODESET
# include <langinfo.h>
#endif

#include "system.h"
#include "argmatch.h"
#include "closeout.h"
#include "error.h"
#include "getdate.h"
#include "getline.h"
#include "posixtm.h"
#include "posixver.h"
#include "timespec.h"

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "date"

#define AUTHORS "David MacKenzie"

int putenv ();

size_t nstrftime PARAMS ((char *, size_t, char const *,
			  struct tm const *, int, int));

static void show_date PARAMS ((const char *format, struct timespec when));

enum Time_spec
{
  /* display only the date: 1999-03-25 */
  TIME_SPEC_DATE=1,
  /* display date and hour: 1999-03-25T03-0500 */
  TIME_SPEC_HOURS,
  /* display date, hours, and minutes: 1999-03-25T03:23-0500 */
  TIME_SPEC_MINUTES,
  /* display date, hours, minutes, and seconds: 1999-03-25T03:23:14-0500 */
  TIME_SPEC_SECONDS
};

static char const *const time_spec_string[] =
{
  "date", "hours", "minutes", "seconds", 0
};

static enum Time_spec const time_spec[] =
{
  TIME_SPEC_DATE, TIME_SPEC_HOURS, TIME_SPEC_MINUTES, TIME_SPEC_SECONDS
};

/* The name this program was run with, for error messages. */
char *program_name;

/* If nonzero, display an ISO 8601 format date/time string */
static int iso_8601_format = 0;

/* If non-zero, display time in RFC-(2)822 format for mail or news. */
static int rfc_format = 0;

#define COMMON_SHORT_OPTIONS "Rd:f:r:s:u"

static struct option const long_options[] =
{
  {"date", required_argument, NULL, 'd'},
  {"file", required_argument, NULL, 'f'},
  {"iso-8601", optional_argument, NULL, 'I'},
  {"reference", required_argument, NULL, 'r'},
  {"rfc-822", no_argument, NULL, 'R'},
  {"set", required_argument, NULL, 's'},
  {"uct", no_argument, NULL, 'u'},
  {"utc", no_argument, NULL, 'u'},
  {"universal", no_argument, NULL, 'u'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

#if LOCALTIME_CACHE
# define TZSET tzset ()
#else
# define TZSET /* empty */
#endif

#ifdef _DATE_FMT
# define DATE_FMT_LANGINFO() nl_langinfo (_DATE_FMT)
#else
# define DATE_FMT_LANGINFO() ""
#endif

void
usage (int status)
{
  if (status != 0)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("\
Usage: %s [OPTION]... [+FORMAT]\n\
  or:  %s [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]\n\
"),
	      program_name, program_name);
      fputs (_("\
Display the current time in the given FORMAT, or set the system date.\n\
\n\
  -d, --date=STRING         display time described by STRING, not `now'\n\
  -f, --file=DATEFILE       like --date once for each line of DATEFILE\n\
  -ITIMESPEC, --iso-8601[=TIMESPEC]  output date/time in ISO 8601 format.\n\
                            TIMESPEC=`date' for date only,\n\
                            `hours', `minutes', or `seconds' for date and\n\
                            time to the indicated precision.\n\
                            --iso-8601 without TIMESPEC defaults to `date'.\n\
"), stdout);
      fputs (_("\
  -r, --reference=FILE      display the last modification time of FILE\n\
  -R, --rfc-822             output RFC-822 compliant date string\n\
  -s, --set=STRING          set time described by STRING\n\
  -u, --utc, --universal    print or set Coordinated Universal Time\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
FORMAT controls the output.  The only valid option for the second form\n\
specifies Coordinated Universal Time.  Interpreted sequences are:\n\
\n\
  %%   a literal %\n\
  %a   locale's abbreviated weekday name (Sun..Sat)\n\
"), stdout);
      fputs (_("\
  %A   locale's full weekday name, variable length (Sunday..Saturday)\n\
  %b   locale's abbreviated month name (Jan..Dec)\n\
  %B   locale's full month name, variable length (January..December)\n\
  %c   locale's date and time (Sat Nov 04 12:02:33 EST 1989)\n\
"), stdout);
      fputs (_("\
  %C   century (year divided by 100 and truncated to an integer) [00-99]\n\
  %d   day of month (01..31)\n\
  %D   date (mm/dd/yy)\n\
  %e   day of month, blank padded ( 1..31)\n\
"), stdout);
      fputs (_("\
  %F   same as %Y-%m-%d\n\
  %g   the 2-digit year corresponding to the %V week number\n\
  %G   the 4-digit year corresponding to the %V week number\n\
"), stdout);
      fputs (_("\
  %h   same as %b\n\
  %H   hour (00..23)\n\
  %I   hour (01..12)\n\
  %j   day of year (001..366)\n\
"), stdout);
      fputs (_("\
  %k   hour ( 0..23)\n\
  %l   hour ( 1..12)\n\
  %m   month (01..12)\n\
  %M   minute (00..59)\n\
"), stdout);
      fputs (_("\
  %n   a newline\n\
  %N   nanoseconds (000000000..999999999)\n\
  %p   locale's upper case AM or PM indicator (blank in many locales)\n\
  %P   locale's lower case am or pm indicator (blank in many locales)\n\
  %r   time, 12-hour (hh:mm:ss [AP]M)\n\
  %R   time, 24-hour (hh:mm)\n\
  %s   seconds since `00:00:00 1970-01-01 UTC' (a GNU extension)\n\
"), stdout);
      fputs (_("\
  %S   second (00..60); the 60 is necessary to accommodate a leap second\n\
  %t   a horizontal tab\n\
  %T   time, 24-hour (hh:mm:ss)\n\
  %u   day of week (1..7);  1 represents Monday\n\
"), stdout);
      fputs (_("\
  %U   week number of year with Sunday as first day of week (00..53)\n\
  %V   week number of year with Monday as first day of week (01..53)\n\
  %w   day of week (0..6);  0 represents Sunday\n\
  %W   week number of year with Monday as first day of week (00..53)\n\
"), stdout);
      fputs (_("\
  %x   locale's date representation (mm/dd/yy)\n\
  %X   locale's time representation (%H:%M:%S)\n\
  %y   last two digits of year (00..99)\n\
  %Y   year (1970...)\n\
"), stdout);
      fputs (_("\
  %z   RFC-822 style numeric timezone (-0500) (a nonstandard extension)\n\
  %Z   time zone (e.g., EDT), or nothing if no time zone is determinable\n\
\n\
By default, date pads numeric fields with zeroes.  GNU date recognizes\n\
the following modifiers between `%' and a numeric directive.\n\
\n\
  `-' (hyphen) do not pad the field\n\
  `_' (underscore) pad the field with spaces\n\
"), stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  exit (status);
}

/* Parse each line in INPUT_FILENAME as with --date and display each
   resulting time and date.  If the file cannot be opened, tell why
   then exit.  Issue a diagnostic for any lines that cannot be parsed.
   If any line cannot be parsed, return nonzero;  otherwise return zero.  */

static int
batch_convert (const char *input_filename, const char *format)
{
  int status;
  FILE *in_stream;
  char *line;
  int line_length;
  size_t buflen;
  struct timespec when;

  if (strcmp (input_filename, "-") == 0)
    {
      input_filename = _("standard input");
      in_stream = stdin;
    }
  else
    {
      in_stream = fopen (input_filename, "r");
      if (in_stream == NULL)
	{
	  error (EXIT_FAILURE, errno, "`%s'", input_filename);
	}
    }

  line = NULL;
  buflen = 0;
  status = 0;
  while (1)
    {
      line_length = getline (&line, &buflen, in_stream);
      if (line_length < 0)
	{
	  /* FIXME: detect/handle error here.  */
	  break;
	}

      when.tv_sec = get_date (line, NULL);
      when.tv_nsec = 0; /* FIXME: get_date should set this.  */

      if (when.tv_sec == -1)
	{
	  if (line[line_length - 1] == '\n')
	    line[line_length - 1] = '\0';
	  error (0, 0, _("invalid date `%s'"), line);
	  status = 1;
	}
      else
	{
	  show_date (format, when);