Shell Programming and Scripting

I dont know if there was a misunderstanding, but I am trying to get the script to buffer the last n lines that were parsed through it... n is a command-line argument

The biggest problem is file size... if I run the while loop that runs the sed, that ends up being n-squared time... which for a ~1GB log file = disaster

I wish I could use the solution posted here: Extracting Data From Large Logs but unfortunately I dont have a simple search... instead, I have to first search for a discrepancy and then print out n+/-x lines

This is what I have working so far (no buffer implemented):

Code:

egrep -n '^[0-9]' $file | \
while IFS="[.|:]" read number datetime min sec milli rest; do
    milliseconds=$(date -d "$datetime:$min:$sec" +%s)$milli
    line="$number:$datetime:$min:$sec.$milli|$rest"
    if [[ $previous -ne 0 ]] ; then
        (( difference = milliseconds - previous ))
    else
        difference=0
    fi
    if [[ $difference -gt $maxTime ]] ; then
        echo $line
    fi
    previous=$milliseconds
done