create a directory with multiple files in it
mkdir this_dir
touch this_dir/one.txt
touch this_dir/one.csv
Now we can find all files in that directory called one (no matter file extension)
for filename in this_dir/one.*; do
echo $filename
done
The above should print:
this_dir/one.csv
this_dir/one.txt
Great, but wait! There are bugs lurking....
What if the directory is empty?
rm this_dir/*
Now the above code would break oddly:
for filename in this_dir/one.*; do
echo $filename
done
Now returns, when the directory is empty, this:
this_dir/one.*
Ack!. WTF bash! Instead of the search pattern being printed a more logical thing would be for the for loop to never run since no items are found.
We can fix the behavior by doing:
shopt -s nullglob
Now the loop will only find files if they exist.
Great, but wait! There is another gocha lurking...
DO NOT quote the search search. You need to use for filename in this_dir/one.*; do and not for filename in "this_dir/one.*"; do
Let's add back the files so we can test again:
touch this_dir/one.txt
touch this_dir/one.csv
If you unknowning quoted the search string the result would be:
this_dir/one.csv this_dir/one.txt
Which is problematic since that is one string with both filenames included. Not what we want.