my $scan = 'foo';
# here $scan == 'foo';

if ( $something ) {
    my $scan = 'bar';
    # here $scan == 'bar';
}

# now the $scan we defined in the if() {} is out of scope,
# gone, defunct, forgotten, inaccessible so $scan == 'foo'

##</code><code>##

print "
        =======================================
        Here is my really groovy script
        I hope you like it
        Call it with --help to get the synopsis
        =======================================

";

##</code><code>##

print "Oops";
die;

# might as well be
die "Oops";

##</code><code>##

open FILE, $somefile or die "Could not read $somefile, perl says the error is $!\n";

# note if you want to use || rather than or you need to be aware 
# that it binds tighter than the , operator so you need parnes thusly

open (FILE, ">$somefile") || die "Could not write $somefile, $!\n";

##</code><code>##

while ( my $line=<FILE> ) { blah }

##</code><code>##

volume ;my_hacking_script_that_will_now_get_executed.pl

##</code><code>##

system(@stuff)
check_call($custom_message,@stuff);

sub check_call {
    my $custom_message = shift;
    my @call = @_;
    # check for 0 return status
  return unless $?;
    # bugger, we have an error so tell all
    # Work out return code
    my $rc = $? >> 8;
    die qq!

System call failed
Error code $rc
$custom_message
Actual call was
system( "@call" )!;
}

##</code><code>##

use Carp;

one();

sub one { two() }
sub two { three() }
sub three{ confess "It took a while to get here, but I know just how I did!" }

__DATA__
It took a while to get here, but I know just how I did! at script line 7
	main::three() called at script line 6
	main::two() called at script line 5
	main::one() called at script line 3

##</code><code>##

#!/usr/bin/perl -w
use strict;
use Error::Custom;
synopsis() unless @ARGV;
system(@args);
check_call('custom message',@args); # this lives in Error::Custom
system(@args1);
check_call('more custom messages',@args1);
exit;

sub synopsis {
    # note that $0 contains the script name so the name will
    # always be the correct one no matter what you call the script
    print "

    Synopsis $0 SOME_FLAG SOME_ARG
    blah
    blah\n\n";
  exit;
}

##</code><code>##

package Error::Custom;

use strict;
use Exporter;
use Carp;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK );

$VERSION     = 1.00;
@ISA         = qw(Exporter);
@EXPORT      = qw(check_call);
@EXPORT_OK   = qw(check_call);

sub check_call {
    my $custom_message = shift;
    my @call = @_;
    # check for 0 return status
  return unless $?;
    # bugger, we have an error so tell all
    # Work out return code
    my $rc = $? >> 8;
    confess qq!

System call failed
Error code $rc
$custom_message
Actual call was
system( "@call" )
    !;
}

1;