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

my $infile = 'bogus_name';

open IN, '<', $infile or warn "$!";

# No such file or directory at C:\TEMP\demoOpenMessage.pl line 6.

open IN, '<', $infile or 
     warn "cannot open $infile for reading";
     
#cannot open bogus_name for reading 
# at C:\TEMP\demoOpenMessage.pl line 6.
         
open IN, '<', $infile or  
     warn "cannot open $infile for read-> $!";

#cannot open bogus_name for read-> No such file 
#   or directory at C:\TEMP\demoOpenMessage.pl line 12.

open IN, '<', $infile or  
     warn "cannot open $infile for read-> $!\n";
     
#cannot open bogus_name for read-> No such file or directory