Shell Programming and Scripting

I have output from a file like this:

Code:

15,01,11,14:06
235

I would like to change this to:

Code:

15,01,11,14:06,235

Removing newline and change to ","
I now this can be done with tr
cat OUT | tr '\n' ',''

My problem is that tr is not implemented in this shell. sed is, show it should be possible using sed, but how?

---------- Post updated at 03:09 PM ---------- Previous update was at 02:27 PM ----------

After some more investigating, I did find this:

Code:

cat OUT | sed -n -e 'H;${x;s/\n/,/g;s/^,//;p;}'

It gives me desire result, but have no clue what it does