my $file = '/some/secret/path/to.file';
 open(my $fh, "<$file") or die "Error opening $file: $!";
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... Oh... the many ways of "death"

In many cases (like file open), the $! sequence doesn't matter because it expands to the generic "No such file or directory" message shown below. This adds no value to the error message.

Adding a "\n" to the die message suppresses the source code line where the error occurred.

For a failed open(), I often just put: die "unable to open $file"; .. What would adding $! to that message offer? In realistic terms, wrong name, wrong path, wrong permissions and the "hunt" starts there.

When the "die error message" is written, it it up to coder to decide what information to divulge (or not!).

#!/usr/bin/perl -w
use strict;

my $file = '/some/secret/path/to.file';
# open(my $fh, "<$file") or die "Error opening $file: $!";
#   error prints: Error opening /some/secret/path/to.file: 
#      No such file or directory at C:\TEMP\junk3.pl line 6.
  
my $file1 = '/some/secret/path/to.file';
# open(my $fh, "<$file1") or die "Error opening $file1\n";
#   error prints: Error opening /some/secret/path/to.file
 
my $file2 = '/some/secret/path/to.file';
#open(my $fh, "<$file2") or die "$!";
#   error prints: No such file or directory at C:\TEMP\junk3.pl line 1
+5.
  
my $file3 = '/some/secret/path/to.file';
#open(my $fh, "<$file3") or die "$!\n";
#   error prints: No such file or directory

my $file4 = '/some/secret/path1/to.file';
#open(my $fh, "<$file4") or die "";
#   error prints: Died at C:\TEMP\junk3.pl line 31.

my $file5 = '/some/secret/path4/to.file';
open(my $fh, "<$file5") or die "\n";
#   error prints: NOTHING!
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