Rodrick Brown wrote:
> On Sun, Jun 8, 2008 at 10:37 AM, Gunnar Hjalmarsson <[EMAIL PROTECTED]>
> wrote:
>
>> Rodrick Brown wrote:
>>
>>> #!/usr/bin/perl -w
>>>
>> The -w switch is redundant, since you have "use warnings;".
>>
>> use strict;
>>> use warnings;
>>> use Data::Dumper;
>>> my $file = '/etc/passwd';
>>> my $hash;
>>> my ($user, $homeDir);
>>> my $count=0;
>>>
>> Why did you declare that variable?
>>
>> open(my $fh, "<", $file) or die("Fatal error unable to read $file: $!");
>>> while(<$fh>) {
>>> next if /^#/;
>>> ($user, $homeDir) = (split /:/,$_)[0,5];
>>> $hash->{$homeDir} = $user;
>>>
>> You probably want:
>>
>> push @{ $hash->{$homeDir} }, $user;
>>
>> }
>>> print Dumper($hash);
>>
> Yes please explain how exactly that line works? I know @{} dereferences an
> array so it looks like your pushing each user into an anonymous array.
Exactly. The value of a hash element can only be a scalar, and so must represent
a list of items using a reference to an anonymous hash. The syntax
push @{ $hash->{$homeDir} }, $user;
is concise because of 'autovivifaction', which will initialise the hash element
with an implied
$hash->{$homeDir} = [];
if it doesn't already exist.
You should take a look at
perldoc perlref
and
perldoc perllol
to understand further.
HTH,
Rob
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