$ cat foo
abcd line1
defg line2

$ cat foo | { while IFS= read line; do printf "$line\n"; done; }
abcd line1
defg line2

# ok, this fail. I keep just for reference
#IFS= read var << EOF

read var << EOF
$(printf "1a\n2b\n")
EOF

set -- $var
printf "%s" $var

# another working example: 
#(note: 1 each line for only one number)
#       2 cat won't finish until key in Ctrl+d
--
sum=0
for num in `cat`; do
   sum=$((sum+num))
done

printf "sum=%s\n" $sum


# other way
--
cat "$@" |
while read -r line
do
    echo "$line"
done

# this work too
while read -r line
do
    echo "$line"
done < /dev/stdin