#!/bin/bash
#
#

# check command-line for correct usage
if [ $# -ne 1 ]
then
    echo "Usage: ${0##*/} <filename>"
    exit 1
fi

# store the filename
dataFile=$1

# prompt for search date string
read -p "Enter Search Date [i.e. August 09 17:15 2013]: " dateString

# confirm something was entered
if [ ! "$dateString" ]
then
    echo "Must Enter A Value."
    exit 1
fi

# lets grep to see if the string is in the file
statString=$(grep -c "$dateString" "$dataFile")

# if it's there, then that was easy, if not,
# then let's begin substracting 1 minute from the time
# until we find a match
if [ $statString -eq 1 ]
then
    awk "/$dateString/,0" "$dataFile"
else
    while :
    do
        newdateString=$(date '+%B %d %H:%M %Y' --date "$dateString EDT -1 min")
        unset statString
        statString=$(grep -c "$newdateString" "$dataFile")
        if [ $statString -eq 1 ]
        then
            awk "/$newdateString/,0" "$dataFile"
            exit 0
        fi
    done
fi

# done
exit 0

./srchDate.sh data.txt
Enter Search Date [i.e. August 09 17:15 2013]: August 09 17:22 2013
August 09 17:22 2013
August 09 17:23 2013
August 09 17:24 2013

./srchDate.sh data.txt
Enter Search Date [i.e. August 09 17:15 2013]: August 09 17:18 2013
August 09 17:17 2013
August 09 17:19 2013
August 09 17:20 2013
August 09 17:21 2013
August 09 17:22 2013
August 09 17:23 2013
August 09 17:24 2013