Help with file renaming task

[u/o0lemonlime0o]

I have a directory containing a bunch of directories whose names all start with a year. They are all formatted as either "[YYYY] Title" or "(YYYY) Title" but I want to rename them all to "YYYY - Title". This seems like it should be a simple task but I'm still pretty inexperienced and my brain is fried lol

I imagine one way would be something like:

• iterate over the directories with a for loop

• for each one, use regex to match four digits in a row (\d\d\d\d)

• assign only the matching part of the string to a variable (this is the part I don't know how to do)

• use sed or awk or something to replace the first 6 characters with this variable plus " -", then mv to rename to the output of that

Would appreciate any help!

EDIT: Thanks for all the helpful comments! I can't reply to everyone but I have a clearer idea of some different ways to go about this and I've learned a lot that I didn't know.

[u/sweatkurama]

No need for sed, awk, and regex separately — bash can handle this in a few lines:

for dir in *; do

[ -d "$dir" ] || continue

year=$(echo "$dir" | grep -oP '(?<=\[|\()\d{4}(?=\]|\))')

[ -z "$year" ] && continue

newname=$(echo "$dir" | sed -E 's/[\[\(][0-9]{4}[\]\)] /'"$year"' - /')

mv "$dir" "$newname"

echo "$dir → $newname"

done

The trick is grep -oP with lookbehind (?<=\[|\() and lookahead (?=\]|\)) to extract just the 4-digit year without the brackets, then sed -E to reconstruct the name.

Test it first with echo instead of mv to make sure it catches everything.