Why does unix while read not read last line? [duplicate]

Answer 1

This is an extensive reading for the question why?

If you don't want to put a new line at the end, you can do this:

while IFS=: read -r a b c d || [ -n "$a" ]; 
do     
echo $a,$b,$c,$d; 
done < file

Or using grep:

while IFS=: read -r a b c d; 
do     
echo $a,$b,$c,$d; 
done < <(grep "" filee)

Note:

1. There's no need to use cat with while loop.
2. You should almost always use the -r option with read.