[Help-bash] Getting rid of white space with % and %%

[Bill Gradwohl]

I noticed it's apparently legit to say the following:

string='hello this  is   a    test     '
echo "'${string}'" original

echo "'${string%[[:space:]]}'"
echo "'${string%[[:space:]]*}'"
echo "'${string%%[[:space:]]*}'"

Produces:
address@hidden ycc# ./tst
'hello this  is   a    test     ' original
'hello this  is   a    test    '
'hello this  is   a    test    '
'hello'

I tried it with a tab character at the end of the string and that also works.

Is there any syntactically correct way to provide an * or + multiplier on to this to get rid of all the white space at the end of a line?

-- 
Bill Gradwohl