sqlplus removes extra whitespace

It isn't SQL*Plus doing that, it's the shell. You need to enclose your variable in quotes:

To preserve whitespace within a string or in a variable, use quoting.

So instead of

echo ${sql_out}

do either of these:

echo "${sql_out}"printf "%s\n" "${sql_out}"

and the output will then be:

aaaa  vvvv   cccc

CodeHunter