For anyone looking for a GUI tool I like to use krename.

Tested this with perl-rename and it seems to work fine:

perl-rename -n 's/.* (\d{1,2}).* (\d{1,2})/sprintf "S%02dE%02d",$1,$2/e' *

. represents any single character

‘*’ matches the previous character 1 or more times

'.* ’ matches any series of characters before a space

() encloses something you want to keep

\ is the escape character

d represents any number

{1,2} means the number will be 1 or 2 digits

In the sprintf, %02d is to format each number with 2 digits.

$1 and $2 pass the first and second values enclosed in parentheses from the first argument into the 2 d’s in the “S%02dE%02d” of the second argument.

This link has a better explanation of the /e modifier than I could give you xD

https://www.geeksforgeeks.org/perl/perl-e-modifier-in-regular-expression/

I think you want something like this:

$ ls
'Star Trek Next Generation Season 01 Episode 22 - Bob.mkv'
'Star Trek Next Generation Season 1 Episode 1 - Encounter at Farpoint.mkv'
$ file-rename 's/.*Season (\d+) Episode (\d+)/sprintf("S%02dE%02d", $1, $2)/ie' *.mkv
$ ls
'S01E01 - Encounter at Farpoint.mkv'  'S01E22 - Bob.mkv'

If you are getting an angle bracket, it’s probably because you didn’t add *.mkv at the end.

This is the kinda small script I use Claude for. So yeh, it’s LLM generated. Downvote away.
But I am terrible at writing bash scripts!

#!/usr/bin/env bash
# rename-episodes.sh — run inside the folder, or pass a directory as $1

shopt -s nullglob
cd "${1:-.}" || exit 1

for f in *.mkv; do
    # Match: ... Season N ... Episode N - Title.mkv
    if [[ $f =~ Season\ ([0-9]+)\ Episode\ ([0-9]+)\ -\ (.+)\.mkv$ ]]; then
        season="${BASH_REMATCH[1]}"
        episode="${BASH_REMATCH[2]}"
        title="${BASH_REMATCH[3]}"

        # Zero-pad to two digits
        new=$(printf "S%02dE%02d - %s.mkv" "$season" "$episode" "$title")

        if [[ "$f" != "$new" ]]; then
            echo "mv: $f  ->  $new"
            # uncomment the next line to actually move the file
            # mv -n -- "$f" "$new"
        fi
    else
        echo "skip (no match): $f"
    fi
done

I’ve commented out the mv command so you can test/fiddle/play around with it without clobbering your files.

Some notes from Claude:

Two practical notes:
If your files aren’t all .mkv, change the glob (*.mkv) and the regex anchor accordingly, or loop over *.{mkv,mp4,avi}.
This assumes the literal words “Season” and “Episode” appear. If your real filenames vary (e.g. “S1”, “1x01”, “Ep 1”), the regex needs adjusting

Edit: I just realised that specifically file-rename is mentioned, and looks like you are getting appropriate help in other threads.

I recommend using a tool designed just for this: https://www.tweaking4all.com/home-theatre/rename-my-tv-series-v2/

Share the rename commands you’ve tried

I’ll look into it. I’m going to be running a media server eventually, so thinking learning the command line arguments would be a good investment.

In this case, I’m moving these onto DVD and the truncated file names will all look the same on the DVD player, so I need to shorten 24*7 files.

Re-phrased the title. It’s a plain language question.

what’s the outcome you’re trying to achieve? you’ve got a folder full of mkv files and you just want to rename them?

why not keep it simple and use a for loop with mv and awk to perform the rename?

To me, your problem feels like the command you’re trying to execute isn’t complete syntax-wise. It may be useful if you’d quote the actual command you’re trying to execute.

This doesn’t answer your question at all, so my apologies up front.

I’m not at all intending to advertise here, and I’m not at all affiliated with them, but in the past, I’ve sidestepped having to write scripts by using FileBot. It’s always just worked for me.

mv “Star Trek Next Generation Season 1 Episode 1 - Encounter at Farpoint.mkv” “S01E01 - Encounter at Far Point.mkv”  

Or am I missing something about what you’re trying to do?

mv