How can I remove the leading “Modeline” text with sed?

Your `MODENAME` variable contains only the text inside the quotes, such as `1440x800_60.00`. It no longer contains `Modeline`, so there is nothing for the sed command to remove. If you want the mode name, your existing awk extraction is enough:

`MODENAME=$(awk -F'"' '{print $2}' <<< "$LINE")`

If you want to strip `Modeline` from the full gtf output, apply sed to `LINE` instead.

There are two separate issues. First, standard sed uses basic regular expressions, where `+` is normally a literal plus sign. Use `.*` or enable extended regular expressions with `sed -E`:

`sed -E 's/^[[:space:]]*Modeline.+$//'`

But this expression removes the entire matching line, not just the word `Modeline`. To remove the prefix and keep the rest, use:

`sed -E 's/^[[:space:]]*Modeline[[:space:]]*//'`

Also, `s` is not portable in sed; use `[[:space:]]` instead.

A compact approach is to extract the quoted mode name directly from gtf output:

`MODENAME=$(gtf "$WIDTH" "$HEIGHT" "$RATE" | sed -nE 's/^[[:space:]]*Modeline[[:space:]]+"([^"]+)".*$/1/p')`

This matches the Modeline line and prints only the value inside the quotes. Also quote variables when expanding them, and prefer `printf` over `echo` when predictable output matters.