Shell Programming and Scripting

I have a large file where some lines have been split into two lines; some of them even with white spaces before the second line. e.g in the following text I want to merge only specific lines ( say UNIX is cool), also removing white spaces only between them, others shall remain same on the output. Any idea?

e.g

UNIX is coo
l
LINUX is also coo
l
UNIX is coo
l
abcdefgh
UNIX is coo
l
ijklmono qrstuv
l
UNIX is cool
LINUX is coo
l

Note, there may be white spaces after the first line and before the second line also for the specific lines ( say UNIX is coo \n l). any idea

Try :

Code:

awk ' { if ($0 ~ /^UNIX/ ) { print $0;getline;x=$0;print; } }' file  |sed '$!N;s/\n//'

It doesn't work. 2 issues
1. The output doesn't have any lines other than the one with UNIX
2. On the merged lines, The original whitespaces before the second lines are not removed

Any idea

Code:

while read -r line
do
    case $line in
        "UNIX is cool") echo $line;;
        "UNIX is coo") 
            read nextline
            echo "$line$nextline"
            ;;
        * ) echo $line;;
    esac 
done < file