regex - Bash: loop through files that DO NOT match extension

Question

I'm writing a bash script that needs to loop files inside a directory that do not match a specific extension. So far, I've found that the following code loops all files that matches the given extension:

for f in *.txt ; do
    echo $f;
done

How could insthead loop through files that do not match the specified extension?

Answer 1

You can pattern-match with the == operator.

for f in *; do
    [[ $f == *.txt ]] && continue
    # [[ $f != *.txt ]] || continue
    ...
done

If this might run in an empty directory, either use shopt -s nullglob prior to the loop, or put [ -e "$f" ] || continue in side the loop. (The former is preferable, as it avoids constantly checking if a file exists.)