I'm reminded what someone told me the first time I got on the U-bahn in Berlin with my bike: "Das hast Du voellig verkehrt getan." I figured out what signs he was pointed at and never made the same mistake. Were it only one and done with perl....

So there's the base directory of the script. I wouldn't want output there. I've now put a module in the lib folder that presumably would be done before release. It is certainly not in such a state now. Given that we need a "hard" output file, would you rather put such a thing on our one and only subdirectory or split input and output into separate directories? Won't that complicate diff'ing?

And they may change over time. For example, I added a module to lib/ which brought the size of the zip file from 1.1 to 3.1 k. Should I go update that on the original post?

For this subthread, I would like to stick to the SSCCE input you offered.

I tend to think that it provides context; where I might describe a situation completely "verkehrt," the computer commands inform the sleuths who can divine what I am actually asking my computer to do. Sometimes I can get too cute. Sometimes, I can't read my own input or output. We have to be somewhat ecumenical about the starts of scripts. Might pre tags work here? I'll put pre tags on the output and invocation line, and leave everything inside code tags be an executable.

$ ./3.rm.pl 
"abcdef", "abcdefg", "abcde", " bcdefgh", " bcd "
"abcdef", "abcdef", "abcde ", " bcdef"
inside first anonymous block
Can't use string ("abcdef") as an ARRAY ref while "strict refs" in use at ./3.rm.pl line 59.
$ cat 3.rm.pl 

#!/usr/bin/perl -w
use 5.011;
use Data::Dump;

my $input = <<'(END INPUT)';
abcdef
abcdefg
abcde
 bcdefgh
 bcd    
(END INPUT)

$input=~ s/\t/ /g;
my @lines = split /\n/, $input;
dd \@lines;
my $out = make_rectangular( \@lines, 4, 6 );
dd $out;

use Test::More;

{
  say "inside first anonymous block";
  my $subset = getsubset( $out, "R1" );
  is_deeply $subset, [ [ 'a' .. 'f' ] ];
  say "exiting first anonymous block";
}


sub make_rectangular {
    my ( $lines, $maxrows, $maxlength ) = @_;
    my @out;
    my $rowcount=1;
    for my $line (@$lines) {
        my $trimmed = substr $line, 0, $maxlength;
        push @out, sprintf "%-*s", $maxlength, $trimmed;
        last if ++$rowcount>$maxrows;
    }
    return \@out;
}

sub rangeparse {
  use Carp;
  local $_ = shift;
  my @o;    # [ row1,col1, row2,col2 ] (-1 = last row/col)
  if ( @o = /\AR([0-9]+|n)C([0-9]+|n):R([0-9]+|n)C([0-9]+|n)\z/ ) { }
  elsif (/\AR([0-9]+|n):R([0-9]+|n)\z/) { @o = ( $1, 1, $2, -1 ) }
  elsif (/\AC([0-9]+|n):C([0-9]+|n)\z/) { @o = ( 1, $1, -1, $2 ) }
  elsif (/\AR([0-9]+|n)C([0-9]+|n)\z/) { @o = ( $1, $2, $1, $2 ) }
  elsif (/\AR([0-9]+|n)\z/) { @o = ( $1, 1, $1, -1 ) }
  elsif (/\AC([0-9]+|n)\z/) { @o = ( 1, $1, -1, $1 ) }
  else                      { croak "failed to parse '$_'" }
  $_ eq 'n' and $_ = -1 for @o;
  return \@o;
}

sub getsubset {
  use Carp;
  my ( $data, $range ) = @_;
  my $cols = @{ $$data[0] };
  @$_ == $cols or croak "data not rectangular" for @$data;
  $range = rangeparse($range) unless ref $range eq 'ARRAY';
  @$range == 4 or croak "bad size of range";
  my @max = ( 0 + @$data, $cols ) x 2;
  for my $i ( 0 .. 3 ) {
    $$range[$i] = $max[$i] if $$range[$i] < 0;
    croak "index $i out of range"
      if $$range[$i] < 1 || $$range[$i] > $max[$i];
  }
  croak "bad rows $$range[0]-$$range[2]" if $$range[0] > $$range[2];
  croak "bad cols $$range[1]-$$range[3]" if $$range[1] > $$range[3];
  my @cis = $$range[1] - 1 .. $$range[3] - 1;
  return [
    map {
      sub { \@_ }
        ->( @{ $$data[$_] }[@cis] )
    } $$range[0] - 1 .. $$range[2] - 1
  ];
}

__END__
[download]

The ultimate two routines are from Selecting Ranges of 2-Dimensional Data, and work fine with other data.