Shell Programming and Scripting

Date_1: 25/04/2013
Date_2: 20/07/2012

if Date_1 is greater than Date_2 then
do...
else 
do..
fi

#! /bin/sh
olddate=`21/07/2013`
newdate=`22/07/2013`
if [ $olddate -gt $newdate ];then
echo "olddate"
else
echo "newdate"
fi

#! /bin/sh

olddate="21/07/2013"
newdate="22/07/2013"

# Change date string to yyyymmdd format...
olddate=`echo $olddate | awk -F"/" '{printf "%0.4d%0.2d%0.2d\n",$3,$2,$1}'`
newdate=`echo $newdate | awk -F"/" '{printf "%0.4d%0.2d%0.2d\n",$3,$2,$1}'`

if [ `date -d $olddate '+%s'` -gt `date -d $newdate '+%s'` ];then
  echo "olddate"
else
  echo "newdate"
fi

if [ "$olddate" -gt "$newdate" ]; then

#!/bin/sh
#

# define usage if we don't receive the correct
# number of arguments
if [ $# -ne 2 ]
then
    echo "Usage: ${0##*/} <date_1> <date_2>"
    exit 1
fi

# store initial date format
date1=$1
date2=$2

# convert the date format so that we can feed it
# to the date command by swapping the placement
# of the month and day
date_1=$(echo $1 | awk -F/ '{print $2"/"$1"/"$3}')
date_2=$(echo $2 | awk -F/ '{print $2"/"$1"/"$3}')

# convert the dates to seconds since epoch
date_1_seconds=$(date --date="$date_1" +%s)
date_2_seconds=$(date --date="$date_2" +%s)

# now compare the dates
if [ $date_1_seconds -gt $date_2_seconds ]
then
    echo "$date1 is greater than $date2"
else
    echo "$date2 is greater than $date1"
fi

# done
exit 0

./compDate.sh

Usage: compDate.sh <date_1> <date_2>

./compDate.sh 25/04/2013 20/07/2012

25/04/2013 is greater than 20/07/2012