Sorry, I meant to answer Scrutinizer first suggestion.
I use Ubuntu Linux (14.04.0x) and I am using bash.
The problem is this:
I am using a script to download files that all have the same name "-.txt" (without the quotes) and I am trying to write a script that once it downloads the first file (-.txt) it will rename it to "1.txt" (again, without quotes) and so the second downloaded file ( also named -.txt) will be renamed 2.txt.
Since these files are large they do take some time to be downloaded (each files is ~ 120 MB)

Thank you all again

---------- Post updated at 05:55 PM ---------- Previous update was at 05:23 PM ----------

OK, problem solved. It was a bug in the downloading python script.
The script was made to download "ALL" files once launched, and therefore, it will download all files (all with name "-.txt") before the loop moves to the second command which is to rename the files.
I am to fix the bug, and then run the script.

How did I figure it out?
Out of frustration, I wrote this script:

Code:

for i in {1..5}
do
touch ./-.txt
mv ./-txt $i.txt
done

The result was, as I expected (and hoped) 1.txt, ..., 5.txt
so I directed my attention to understand how the python script works (I did not go through the script, though) and watched it, trying to figure out why does it pass the mv command?
I then added a couple of sleep 10 commands after the downloading command and the mv command to make sure how does each step run... and this is how I figured it out.

Thank you all again for your help and suggestions....
Happy Holidays