I've added in 'my' in the 2 if statements. 
#!/bin/perl
use v5.12;
use warnings;

       my $in = $ARGV[0];
       if (! defined $in) {
          die "Usage: $0 filename";
       }


       my $out = $in;
       $out =~ s/(\.\w+)?$/out/;

       if (! open my $in_fh, '<', $in ) {
          die "Can't open '$in': $!";
          }

       if (! open my  $out_fh, '>', $out) {
          die "Can't write '$out': $!";

[download]

Now I see this message: 

Usage: ./exer_9_2 filename at ./exer_9_2 line 7.

[download]

I understand from all of the input, (many thanks to unknown friends), that once the if statement is completed then the message handle closes on its' own. I don't want to go a wider scope just yet as I want to get the basics down as far as opening & closing files. What is this current error telling me? Thanks, Catfish

In reply to Re: First attempt at bringing in file for input/output by catfish1116
in thread First attempt at bringing in file for input/output by catfish1116

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.