Logical AND in shell script while loop

Question

I am trying to compare dates in the while loop of a shell script. The shell script will be controlled by 2 conditions, like the following:

while [ $currentDate -le $currentDateMonthEnd -a $currentDate -le $toDate ]; do
...
done

The above is my current code, which complains of "integer expression expected". I have also tried using && and AND, which also do not work and complains of mismatching braces.

Could someone please provide the syntax to make the above comparison?

One of the variables is not set, or is not a number. You should test the code using something like set -x — Anya Shenanigans
– Anya Shenanigans, Commented Jun 10, 2013 at 14:38
If you are trying to compare full dates as it is, this will not work - as @Petesh notes, a date is not a number. You have to subtract your dates and check the delta/compare the individual days/months/years. — Adrian Frühwirth
– Adrian Frühwirth, Commented Jun 10, 2013 at 14:45
You might want to consider replacing shell scripting, in this application, with a real programming language that has date math functions; you'll probably find that it makes your life much easier to do so. — Aaron Miller
– Aaron Miller, Commented Jun 10, 2013 at 14:46
If you make your date format look like 20130610 for 2013-06-10 (10th June 2013), then you can compare numerically into date order. Pretty much any other date format is not as conventient. — Jonathan Leffler
– Jonathan Leffler, Commented Jun 10, 2013 at 17:03
@Pretesh, you were right. If you could put that as answer, I will accept. — czchlong
– czchlong, Commented Jun 10, 2013 at 18:18

Zombo · Accepted Answer · 2013-06-11 01:02:50Z

1

dc ()
{
  [ $(date +%s -d "$1") $2 $(date +%s -d "$3") ]
}

while dc "$currentDate" -le "$currentDateMonthEnd" && dc "$currentDate" -le "$toDate"
do
  # ...
done

edited Jun 11, 2013 at 1:02

answered Jun 10, 2013 at 15:10

Zombo

1

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Comments

user3367314 · Accepted Answer · 2014-03-29 06:48:20Z

0

following code works for me,

#! /bin/bash

toDate=`echo 2014/03/30 | tr -d "/"`
currentDate=`date +"%Y/%m/%d" | tr -d "/"`
currentDateMonthEnd=`date +%Y/%m/%d -d "-$(date +%d) days +1 month" | tr -d "/"` 

while [[ $currentDate -le $currentDateMonthEnd ]] && [[ $currentDate -le $toDate ]]   
do   
...  
done


#! /bin/sh 

while [ $currentDate -le $currentDateMonthEnd ] && [ $currentDate -le $toDate ] 
do   
...  
done

answered Mar 29, 2014 at 6:48

user3367314

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