RE: date format in ksh

From: Jacques Kilchoer <Jacques.Kilchoer_at_quest.com>
Date: Fri, 26 Oct 2001 19:16:37 -0700
Message-ID: <F001.003B64E6.20011026192017@fatcity.com>

> -----Original Message-----
> From: Suhen Pather [mailto:Suhen.Pather_at_strandbags.com.au]
>
> Thanks for the reply.
> I am passing a hardcoded date.
> I am not getting a date from the
> "date" command in ksh.
>
> What my ksh does is retrieves $1 and must check if the date format
> is in DD-MON-YY eg. 02-FEB-01.
> It uses the hardcoded date (passed in as argument 1) in the script.
> If the date is in another format other than above then it must exit.

I dusted off my old C programming skills (Sorry Mr. Still I still don't know PERL that well). Why not write a "check_date" program that returns 0 for a valid date and 1 for an invalid date?

The date verification function is case-sensitive and only checks for the one format. It also assumes that two-digit years will be prefixed with "20". Modifying it to be more user-friendly is left as an exercise to the alert reader.

/*
 *  verify that date passed to function is a correct date
 *  parameter passed to function must be in the same format
 *   as shell command <<date +"%d-%b-%y">>
 *  example:  check_date 26-Jan-01
 *            echo $?
 *            check_date 32-Jan-01
 *            echo $?
 *
 *  program assumes that %b date format will return a string with 3 characters
 */
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>

#include <string.h>
#include <time.h>

#define B_DTFMT_LEN 3
#define DT_LEN 6 + B_DTFMT_LEN
#define HIGH_MM 11
#define CBASE_YEAR 1900
#define BASE_YEAR 2000

extern int main (int argc, char **argv)
{

   short int mm ;
   struct tm tmi ;
   time_t t ;
   char month[B_DTFMT_LEN + 1] = { '\0' },
        day[3] = { '\0' },
        compmonth[B_DTFMT_LEN + 1] = { '\0' },
        compdate[DT_LEN + 1] = { '\0' } ;


   if (argc != 2)
   {
      puts ("Usage - check_date \"date\" (date in %d-%b-%y format)") ;

      return EXIT_SUCCESS ;
   }

   if (strlen (argv[1]) != DT_LEN || argv[1][2] != '-'
       || argv[1][3 + B_DTFMT_LEN] != '-'
       || ! isdigit (argv[1][0]) || ! isdigit (argv[1][1])
       || ! isdigit (argv[1][4 + B_DTFMT_LEN])
       || ! isdigit (argv[1][5 + B_DTFMT_LEN]) )
      return EXIT_FAILURE ;

   strncpy (month, argv[1] + 3, B_DTFMT_LEN) ;

   memset (&tmi, '\0', sizeof tmi) ;
   mm = -1 ;
   while (strncmp (month, compmonth, B_DTFMT_LEN) && ++mm <= HIGH_MM)
   {
      tmi.tm_mday = 1 ;
      tmi.tm_mon = mm ;
      tmi.tm_year = 2001 ;
      strftime (compmonth, B_DTFMT_LEN + 1, "%b", &tmi) ;
   }
   if (mm > HIGH_MM)
      return EXIT_FAILURE ;


   strncpy (day, argv[1], 2) ;
   tmi.tm_mday = atoi (day) ;
   tmi.tm_mon = mm ;
   tmi.tm_year = BASE_YEAR + atoi (argv[1] + 4 + B_DTFMT_LEN) - CBASE_YEAR ;

   if ((t = mktime (&tmi)) == (time_t) -1)       return EXIT_FAILURE ;

   tmi = *localtime (&t) ;
   strftime (compdate, DT_LEN + 1, "%d-%b-%y", &tmi) ;
   if (strcmp (argv[1], compdate))
      return EXIT_FAILURE ;

   return EXIT_SUCCESS ;
} Received on Fri Oct 26 2001 - 21:16:37 CDT