How can I remove an element from a Perl array after processing it?

Question

I read the postfix mail log file into an array and then iterate over it to extract the messages. On the first pass, I check the match on the string "to =" and grab the message id. After building the MSGID array, I go back through the array to retrieve information about the lines from =, from = and client =.

What I would like to do is remove the row from the array as soon as I extract the data from it to make the processing a little faster (i.e., another row to check).

Any suggestions? This is in Perl.

---

Edit: gbacon's answer below was enough to get me a ride with a solid solution. Here are his guts:

my %msg;
while (<>) {
    my $line = $_;
    if (s!^.*postfix/\w+\[.+?\]: (\w+):\s*!!) {
            my $key = $1;
            push @{ $msg{$key}{$1} } => $2
                    while /\b(to|from|client|size|nrcpt)=<?(.+?)(?:>|,|\[|$)/g;
    }
    if ($line =~ s!^(\w+ \d+ \d+:\d+:\d+)\s(\w+.*)\s+postfix/\w+\[.+?\]: (\w+):\s*removed!!) {
            my $key = $3;
            push @{ $msg{$key}{date} } => $1;
            push @{ $msg{$key}{server} } => $2;
    }
}

use Data::Dumper;
$Data::Dumper::Indent = 1;
print Dumper \%msg;

, regexp , , . , .

, .

Answer 1

:

#! /usr/bin/perl

use warnings;
use strict;

# for demo only
*ARGV = *DATA;

my %msg;
while (<>) {
  if (s!^.*postfix/\w+\[.+?\]: (\w+):\s*!!) {
    my $key = $1;
    push @{ $msg{$key}{$1} } => $2
      while /\b(to|from|client)=(.+?)(?:,|$)/g;
  }
}

use Data::Dumper;
$Data::Dumper::Indent = 1;
print Dumper \%msg;
__DATA__
Apr  8 14:22:02 MailSecure03 postfix/smtpd[32388]: BA1CE38965: client=mail.example.com[x.x.x.x]
Apr  8 14:22:03 MailSecure03 postfix/cleanup[32070]: BA1CE38965: message-id=<[e-mail]>
Apr  8 14:22:03 MailSecure03 postfix/qmgr[19685]: BA1CE38965: from=<[e-mail]>, size=1087, nrcpt=2 (queue active)
Apr  8 14:22:04 MailSecure03 postfix/smtp[32608]: BA1CE38965: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10025, delay=1.7, delays=1/0/0/0.68, dsn=2.0.0, status=sent (250 OK, sent 49DC509B_360_15637_162D8438973)
Apr  8 14:22:04 MailSecure03 postfix/smtp[32608]: BA1CE38965: to=<[e-mail]>, relay=127.0.0.1[127.0.0.1]:10025, delay=1.7, delays=1/0/0/0.68, dsn=2.0.0, status=sent (250 OK, sent 49DC509B_360_15637_162D8438973)
Apr  8 14:22:04 MailSecure03 postfix/qmgr[19685]: BA1CE38965: removed
Apr  8 14:22:04 MailSecure03 postfix/smtpd[32589]: 62D8438973: client=localhost.localdomain[127.0.0.1]
Apr  8 14:22:04 MailSecure03 postfix/cleanup[32080]: 62D8438973: message-id=<[e-mail]>
Apr  8 14:22:04 MailSecure03 postfix/qmgr[19685]: 62D8438973: from=<[e-mail]>, size=1636, nrcpt=2 (queue active)
Apr  8 14:22:04 MailSecure03 postfix/smtp[32417]: 62D8438973: to=<[e-mail]>, relay=y.y.y.y[y.y.y.y]:25, delay=0.19, delays=0.04/0/0.04/0.1, dsn=2.6.0, status=sent (250 2.6.0  <[e-mail]> Queued mail for delivery)
Apr  8 14:22:04 MailSecure03 postfix/smtp[32417]: 62D8438973: to=<[e-mail]>, relay=y.y.y.y[y.y.y.y]:25, delay=0.19, delays=0.04/0/0.04/0.1, dsn=2.6.0, status=sent (250 2.6.0  <[e-mail]> Queued mail for delivery)
Apr  8 14:22:04 MailSecure03 postfix/qmgr[19685]: 62D8438973: removed

, (, BA1CE38965 62D8438973 ), $key.

( /g), to=<...>, client=mail.example.com .. - .

,

• \b - ( xxxto=<...>)
• (to|from|client) - to from client
• (.+?) -
• (?:,|$) - $3

(.+?) , , .

to=<[e-mail]>, other=123

<[e-mail]>, other=123 !

push ( , , ), , . :

$VAR1 = {
  '62D8438973' => {
    'client' => [
      'localhost.localdomain[127.0.0.1]'
    ],
    'to' => [
      '<[e-mail]>',
      '<[e-mail]>'
    ],
    'from' => [
      '<[e-mail]>'
    ]
  },
  'BA1CE38965' => {
    'client' => [
      'mail.example.com[x.x.x.x]'
    ],
    'to' => [
      '<[e-mail]>',
      '<[e-mail]>'
    ],
    'from' => [
      '<[e-mail]>'
    ]
  }
};

, , BA1CE38965:

my $queueid = "BA1CE38965";
foreach my $recip (@{ $msg{$queueid}{to} }) {
  print $recip, "\n":
}

, , :

print scalar @{ $msg{$queueid}{to} }, "\n";

, ,

print $msg{$queueid}{client}[0], "\n";

Answer 2

, .

:

• , (, ) ,

Answer 3

:

my @extracted = map  extract_data($_), 
                grep msg_rcpt_to( $rcpt, $_ ), @log_data;

, , .

Answer 4

perl splice() .

, .

Answer 5

, , splice:

splice(@array, $indextoremove, 1)

. .

Answer 6

:

# start over with this list for each example:
my @list = qw(a b c d);

:

splice @list, 2, 1, qw(e);
# @list now contains: qw(a b e d)

pop and unshift :

pop @list;
# @list now contains: qw(a b c)

unshift @list;
# @list now contains: qw(b c d)

map

@list = map { $_ eq 'b' ? () : $_ } @list;
# list now contains: qw(a c d);

array fragments :

@list[3..4] = qw(e f);
# list now contais: qw(a b c e f);

for and foreach :

foreach (@list)
{
    # $_ is aliased to each element of the list in turn;
    # assignments will be propogated back to the original structure
    $_ = uc if m/[a-c]/;
}
# list now contains: qw(A B C d);

Read about all these functions in perldoc perlfunc , fragments in perldoc perldata , and for loops in perldoc perlsyn .