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

danpaluska · #1 (**permalink**) 2 Weeks Ago

i've looked at a bunch of the date comparison threads on these boards but unfortunately not been able to figure this thing out yet. still confused by some of the way conditionals handle variables...

here is what i where i am now...

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?

thanks,
dan

durden_tyler · #2 (**permalink**) 2 Weeks Ago

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
$
$

tyler_durden

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Date comparison with 'string date having slashes and time zone' in Bash only	TariqYousaf	Homework & Coursework Questions	1	10-08-2009 01:27 PM
Plz correct my syntax of shell script	girish.batra	Shell Programming and Scripting	2	06-06-2008 06:36 AM
Check for the correct date format in UNIx	rawatds	Shell Programming and Scripting	1	07-13-2006 06:24 AM
correct syntax for using "grep regex filename" ?	yongho	UNIX for Dummies Questions & Answers	2	06-13-2005 02:44 PM
Correct Syntax For Calling Shell Script in Perl Module	mh53j_fe	Shell Programming and Scripting	4	06-08-2005 10:42 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by