Shell Programming and Scripting

Hello,

I am getting an infinite loop from a script in Linux.
Here is the last version of the script in question. As you can see I tried to define everything properly:

Code:

#!/bin/ksh

# Script to loop over a series of dates 

set -ex

typeset -i start_date=20090701
typeset -i end_date=20090720

typeset -i current_date=${start_date}

### *PROBLEMATIC LINE BELOW * Remove to test without !!!

# (We increment the starting day by one so that the conditional loop
#  below will be an "=="
end_date=$(date --date="$end_date 1 day" +%Y%m%d)

until [ $current_date == $end_date ]
do
  
  echo "current date = $current_date "
  ### Calculations ####
  
  # Increase the date by one day 
  current_date=$(date --date="$current_date 1 day" +%Y%m%d)

done

The problem is simple: I want to loop over a series of dates: start_date and end_date.
I wanted to make it "nice" and intuitive and include the end_date in the calculations. If we remove the line:

Code:

 
end_date=$(date --date="$end_date 1 day" +%Y%m%d)

then the scripts works fine - it just obviously stops at a date before the end_date.

Problem is:
If I remove the line that increments the end_date then all is well and the script loops till end_date MINUS one day (obviously). By leaving the line there the scripts loops infinitely ! The current_date does increase but the loop's condition is never executed.

I sense that since the variable values do not affect the condition ( == ), then it probably has something to do with the variable type ???

I also tested with the variables not defined as integers but as strings.

IMPORTANT: The script works and I am not asking for an alternative way (would be nice to see a different approach but it's not necessary).
So, if you have any suggestions I want to understand what i am doing wrong with the *current* script and not a different way of doing this!

Thanks!

PS: I am a newbie but the fact that there are a few ways to define the same things in Korn , Bourne etc, begins to annoy me. I want to learn the proper syntax but it's difficult looking at other peoples code at work and on the net. Script synax and various shells seem to be permissive which makes me pick-up "bad habits" ...

---------- Post updated at 11:53 AM ---------- Previous update was at 10:57 AM ----------

Never mind !... I feel embarrassed.

I simplified the listeing here but in real life I had a second fixed nested llop. Inside that loop i was incrementing the date so it would basically "skip" an increement and the == would never apply.

Thanks anyways and my apologies!....

-S

I would have used -lt instead of ==, so that if it somehow skipped past it would still break the loop.

Absolutely ! Among a whole bunch of other improvements. But the point was for me to understand. Well I did ..... I found a silly logical bug.

Thanks again!