... I would like to sort these filenames based on the number after the last underscore ...

This implies the OPer wants a numeric comparison of an extracted set of digits, so the  <=> (also in Equality Operators; see perlop) numeric comparator would be appropriate here.

In reply to Re^2: Sorting filenames with custom function by AnomalousMonk
in thread Sorting filenames with custom function by Anonymous Monk

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