if [ $NOWDATE -gt $STARTDATE ] , date comparison correct syntax? Post: 302369356

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Top Forums Shell Programming and Scripting if [ $NOWDATE -gt $STARTDATE ] , date comparison correct syntax? Post 302369356 by durden_tyler on Saturday 7th of November 2009 05:24:01 PM

11-07-2009

Registered User

Quote:

Originally Posted by danpaluska

...

Code:

# a bunch of initializition steps are here ...
STARTDATE=`date +%Y%m%d`
 
while [ 1 ] # loop running all the time. 
do

NOWDATE=`date +%Y%m%d`

# if day changes then i want to reinitialize
if [ $NOWDATE -gt $STARTDATE ] 
then
# do all that initiallization again 
fi

# ... a bunch of other code in here

done

but that if statement doesn't work. any tips?
...

Did you wait long enough ?

The value of NOWDATE will change when the day changes. So if you start your script and keep it running till midnight (when the day changes), the "if" condition will return true thereafter.

Code:

$
$ cat -n t1.sh
     1  #!/bin/bash
     2
     3  # a bunch of initializition steps are here ...
     4  STARTDATE=`date +%Y%m%d`
     5  echo "STARTDATE = $STARTDATE"
     6
     7  NOWDATE=`date +%Y%m%d`
     8  if [ $NOWDATE -gt $STARTDATE ]; then
     9    echo "in if (-gt)  : NOWDATE = $NOWDATE"
    10  else
    11    echo "in else (-le): NOWDATE = $NOWDATE"
    12  fi
    13
    14  NOWDATE="20091108"
    15  if [ $NOWDATE -gt $STARTDATE ]; then
    16    echo "in if (-gt)  : NOWDATE = $NOWDATE"
    17  else
    18    echo "in else (-le): NOWDATE = $NOWDATE"
    19  fi
    20
$
$ . t1.sh
STARTDATE = 20091107
in else (-le): NOWDATE = 20091107
in if (-gt)  : NOWDATE = 20091108
$
$

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LEARN ABOUT MINIX

date

DATE(1) 						      General Commands Manual							   DATE(1)

NAME

       date - print or set the date and time

SYNOPSIS

       date [-qsu] [[MMDDYY]hhmm[ss]] [+format]

OPTIONS

       -q     Read the date from stdin

       -s     Set the time (implicit for -q or a date string)

       -u     Print the date as GMT

       -t     Use this number of seconds instead of current time

EXAMPLES

       date		   # Print the date and time

       date 0221921610	   # Set date to Feb 21, 1992 at 4:10 p.m.

DESCRIPTION

       With  the  -q flag or a numeric argument, date sets the GMT time and date.  MMDDYY refers to the month, day, and year; hhmmss refers to the
       hour, minute and second.  Each of the six fields must be exactly two digits, no more and no less.  date always display the date	and  time,
       with  the  default format for the system.  The -u flag request GMT time instead of local time.  A format may be specified with a + followed
       by a printf-like string with the following options:

	 %%  % character
	 %A  Name of the day
	 %B  Name of the month
	 %D  mm/dd/yy
	 %H  Decimal hour on 2 digits
	 %I  Decimal hour modulo 12 on 2 digits
	 %M  Decimal minute on 2 digits
	 %S  Decimal seconds on 2 digits
	 %T  HH:MM:SS
	 %U  Decimal week number, Sunday being first day of week
	 %W  Decimal week number, Monday being first day of week
	 %X  Same as %T
	 %Y  Decimal year on 4 digits
	 %Z  Time Zone (if any)
	 %a  Abbreviated name of the day
	 %b  Abbreviated name of the month
	 %c  Appropriate date & time (default format)
	 %d  Decimal day of the month on 2 digits
	 %e  Same as %d, but a space replaces leading 0
	 %h  Same as %b
	 %j  Decimal dey of the year on 3 digits
	 %m  Decimal month on 2 digits
	 %n  Newline character
	 %p  AM or PM
	 %r  12-hour clock time with AM/PM
	 %s  Number of seconds since the epoch
	 %t  Tab character
	 %w  Decimal day of the week (0=Sunday)
	 %x  Same as %D
	 %y  Decimal year on 2 digits

SEE ALSO

       time(2), ctime(3), readclock(8).

																	   DATE(1)