Perhaps version. Also see the -k and other sorting options in the unix sort options.

If neither of those solve your issue, then perhaps this sort routine:

# Assume: version strings have same numbers of parts.  Adjust if not.
# Note: This is not efficient, but may help explain what needs to happ
+en.
sort {
    my @a_fn_parts  = split( qr([_]), $a );
    my @a_ver_parts = split( qr([.]), @a_fn_parts[1] );

    my @b_fn_parts  = split( qr([_]), $b );
    my @b_ver_parts = split( qr([.]), @b_fn_parts[1] );

    my $i = 0;
    while ( $i < @a_ver_parts ) {
        return $a_ver_parts[ $i ] <=> $b_ver_parts[ $i ]
            if ( $a_ver_parts[ $i ] != $b_ver_parts[ $i ] );
        $i++;
    }
    return 0;
}
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