strange behavior of assignment

[Francky Leyn]

Hello,

consider the following snippet:

EXTENSION=png
INPUT_FILES=*.$EXTENSION

If there are for example 3 input files, an echo delivers:

echo $INPUT_FILES --> '01.png 02.png 03.png'

No we change the EXTENSION:

EXTENSION=jpg

Now, in a dir without jpg files the following happens:

INPUT_FILES=*.$EXTENSION
echo $INPUT_FILES  --> '*.jpg' instead of the empty string.

Is there any way I can optain an empty string?
I would like to test on the zeroness of INPUT_FILES.


Best regards,

Francky Leyn