Please show us your perl1.pl script inside <code> and </code> tags so we can see where you are going wrong. As for working on a multi-line file, calculate the offsets, open your file then do something like

while ( <$inputFH> )
{
    foreach my $offset ( reverse @cums[ 1 .. $#cums ] )
    }
        substr $_, $offset, 0, q{-};
    }
    print;
}
[download]

I hope this moves you forward.

Update: Code modified to replace for statement modifier with an explicit loop, thanks choroba.

Now the file looks like this perl1.pl script looks like this (after some modifications I did from reading the replies

 #!/usr/local/bin/perl 
perl -Mstrict -Mwarnings -E 
my $text =
   q{2013020400000000006810083610022013068100200220130688000200494};
my @offs = ( 17, 6, 31, 3, 3 );
my @cums = ( 0 );
push @cums, $_ + $cums[ -1 ] for @offs;
substr $text, $_, 0, q{-} for reverse @cums[ 1 .. $#cums ];
say $text;
[download]

And the reply I get from running the script is:

biancoari@biancoari ~/Desktop $ perl perl1.pl
syntax error at perl1.pl line 2, near "E
my "
Execution of perl1.pl aborted due to compilation errors.

I will add the


open(FILE, "filename.txt") or die "Could not open file: $!"

and modify the text, any idea if I am heading the right direction?

You need to remove the second line alltogether.

perl -Mstrict -Mwarnings -E
[download]

Replace the second line

perl -Mstrict -Mwarnings -E
[download]

which is for the shell with equivalent Perl lines:

use strict;
use warnings;
use feature 'say';
[download]

لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

syntax error at perl1.pl line 8, near "say $text;'"

Note the single-quote just after the ; (semicolon) in "say $text;'". This closes the quoted code that began with an opening single-quote just after the -E on the first line of the command line invocation in johngg's reply. Get rid of that closing single-quote if you are running the code from a file and things will probably work better.