Trying to replicate example 4 in "Larry's filename fixer" (Perl Cookbook, 9.9), I've tried several variants of his expr: 
  'print "$_: "; s/foo/bar/ if <STDIN> =~ /^y/i'

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and get,for example, the following error: 
  The system cannot find the file specified.

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Running ActivePerl-5.24 on W10, here's the code: 
#!/usr/bin/perl -w

use strict;
use warnings;
use 5.010;

# Larry's filename fixer [Cookbook 9.9, mod crt for ActiveState/W10]

my $op = shift or die 
  "Usage: perl rename expr [files]\n";

chomp(@ARGV = <STDIN>) unless @ARGV;
@ARGV = map glob, @ARGV;

for (@ARGV) {
  my $was = $_;
  eval $op;
  die $@ if $@; 
  rename ($was, $_) unless $was = $_;
}

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Where have I gone astray?

In reply to eval NoOp on cmd.exe line expr by Anonymous Monk

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