Shell Programming and Scripting

Hello all,

I am new to scripting and here is what I want to get done.
I need to run some processing on many files. I have a whole bunch of files among which there are a few that I am interested in. What I need to do is to write a script which reads the file paths from a text file. line by line in a loop and passes that path to the next command in my script which runs the selection criteria as to whether this is a file I want or not. How do I do this? i.e.

1) read the path from the text file in a loop and
2) pass the value read to the next command in my script?

Pls help.. Thanks in advance

Code:

while read FILENAME
do
        do_something_to "$FILENAME"
done < filenames.txt