Shell Programming and Scripting

I have some files in a directory with two different extensions which get created everyday. Can you please help me out in getting the average file size for both these extensions and checking it with the last two file sizes of the same file extension ?

To be more clear..
Lets say I have 10 files of which 5 are with .log and other 5 with .txt extensions.
I need to find average size of all .log files and compare it with the latest created .log file size and report if its size is less

Many thanks in advance

---------- Post updated at 02:13 AM ---------- Previous update was at 01:21 AM ----------

I tried to build up a script and came up with the following snippet:

Code:

AFS= $(ls -l *.log| awk '{sum += $5; n++;} END {sum/n;}')
FS=$(ls -ltr *.log| tail -1 | awk '{print$5}')
for file in $(ls -rt  *.log | tail -1)
do
    if [ ! -s $file ]
    then
echo "$file size is 0"
elif [[ "$FS" -lt "$AFS" ]]
then
echo "$file size is less than average"
fi
done

When I run it, it returns empty.

Code:

elif [[ "$FS" -lt "$AFS" ]]

wondering if this the correct way to compare two values ?

This needs to be corrected
wrong
AFS= $(ls -l *.log| awk '{sum += $5; n++;} END {sum/n;}')
correct
AFS=$(ls -l *.log|awk '{sum+=$5; n++} END {print sum/n}')
Remove space around =