In bash you test like this for problems that can be caused by non-printable characters since if you don't know how to identify it because it basically breaks your script.

echo "url=$url" should print something like this normally if you have properly formatted input/text:

url=::http://someaddress.com::

But if you have some weird hidden characters (not visible in a text editor of any sort you'll get something like this
::l=::http://someaddress.com

How come it doesn't print as expected?
There are hidden/non-printable characters, usually ASCII code I believe that cause unexpected behavior like above and wreaks havoc on many scripts/programs who didn't realize this since there are non-printable characters.

There is a program in Linux that takes care of it called "tr"
If I read data line by line using cat, I now use "tr" to filter all the non-printable characters (I use it line by line and not the entire file since this would remove things like linebreaks and then you have a text file that becomes a single line).

Here is how you'd fix a bad variable (one with non-printable/special characters):

url=`echo "$url"|tr -dc ‘[:print:]‘

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