By setting $/ to '', it enables 'paragraph mode' whereby each read will terminate when two (or more) consecutive newlines are encountered. That allows you to read each multiline record in your output in two chunks. The header line and then the rest:

#! perl -slw
use strict;

$/ = ''; ## Paragraph mode 

while( <DATA> ) {
    m[^(\S+)] or die "Bad input format";
    my $volName = $1;
    $_ = <DATA>;
    m[Serial\sNumber\.+([^\n]+)] or die "Bad input format";
    printf "%8s  %s\n", $volName, $1;
}
__DATA__
...
[download]

use strict;
use warnings;

my $data;
{
    local $/;
    $data = <DATA>;
}

my %drives = ();
while ($data =~ /^(\w+)\s*.*?Serial Number\.*(\w*)\s/smg) {
    $drives{$1} = $2;
}

while ( my ($key, $value) = each %drives) {
    print "$key  $value\n";
}

__DATA__
hdisk0   P1/Z1-Aa     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0009E05B
        Part Number.................09P4436

hdisk1  P1/Z1-Ab     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0004A0D2
        Part Number.................09P4436
[download]

1. ^(\w+) - Find a line that starts with alphanumeric characters
2. \s*.*? - Advance past the smallest amount of arbitrary text until:
3. Serial Number - I encounter the phrase 'Serial Number'
4. \.* - Advance past an arbitrary number of '.' characters
5. (\w*)\s - Find a series of alphanumerics followed by whitespace

Another approach would be to join the lines of the result and match against that. For example:


#!/usr/bin/perl
use strict;
use warnings;

# Slurp!
my @results = <DATA>;
my $results_string = join '', @results;

# Note: Direct assignment to hash works due
# to exactly two matches. Error checking would
# not be a bad idea, either (what happens if the
# match fails?)
my %matches = $results_string =~ /(hdisk\d+).+?Serial Number\.+(\w+)/g
+s;

for my $device (keys %matches) {
    print "$device  $matches{$device}\n";
}
__DATA__
hdisk0   P1/Z1-Aa     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0009E05B
        Part Number.................09P4436

hdisk1  P1/Z1-Ab     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0004A0D2
        Part Number.................09P4436
[download]

Output:


hdisk1  0004A0D2
hdisk0  0009E05B
[download]

#!/usr/bin/perl
use strict;
use warnings;

open(my $cfg, '-|', 'lscfg -vl hdisk*') or die "Unable to open pipe to
+ lscfg: $!";
{
    local $/ = "\nhdisk";
    while (<$fh>) {
        chomp;
        $_ = $/ . $_ if $. != 1;
        my ($disk) = $_ =~ /^(hdisk\w+)/;
        my ($serial) = $_ =~ /Serial Number\.+(\w+)/;
        if ($disk && $serial) {
            print "$disk\t$serial\n";
        }
        else {
            # enhance parser to handle follow situation
            die $_;
        }
    }
}
[download]

That'll screw up on the last record because there is no "\nhdisk" delimiter following it.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

BrowserUk,
Can you explain how it will screw up?

I have subsequently tested it and it works as I expect it to. I did find that on my AIX, the output of the command isn't exactly the same as described by the OP - specifically there are two spaces before hdisk## but after accounting for that, it works as intended. Update: The modifications I made that may make the difference (as I said, it worked as expected) were as follows:

local $/ = "\n  hdisk";
my ($disk) = $_ =~ /\s+(hdisk\w+)/;
[download]

Cheers - L~R

TIMTOWTDI:

#!/usr/bin/perl
use strict;
use warnings;

# pl_test/752902.pl


for (<DATA>) {
    chomp;
    my $data = $_;

    if ( $data =~ m/^(hdisk.)/ ) {
        print "$1 \t";
    }

    if ( $data =~ m/\s+(Serial Number)\.+([\d,A-Z]+)/) {   # alt char 
+class:  [0-9,A-Z] and possibly /i
           print "$1\t$2\n";
    }
}

__DATA__
hdisk0   P1/Z1-Aa     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0009E05B
        Part Number.................09P4436

hdisk1  P1/Z1-Ab     16 Bit LVD SCSI Disk Drive (18200 MB)

        Manufacturer................IBM
        Machine Type and Model......ST318305LC
        FRU Number..................09P4437
        Serial Number...............0004A0D2
        Part Number.................09P4436
[download]

output

hdisk0  Serial Number   0009E05B
hdisk1  Serial Number   0004A0D2
[download]

lscfg -vl hdisk*|perl -MList::Pairwise=mapp -00e'print mapp{$a=~/^(hdi
+sk\d+)/&&"$1 ",$b=~/Serial Number[.]+(\w+)/m&&"$1\n"}<>'
[download]

For completeness, let the record show that you can also choose not to use Perl at all, but rather awk.

awk is a more special-purpose tool, not intended to be a general-purpose programming language. But its “purpose” is very much what you are looking for here. (awk is one of the original “inspirations” for Perl and you'll see that its syntax is quite similar.)

An awk program generally consists of one or more declarations that look like this:

/pattern to look for/
{ block of code to execute anytime the pattern is found }

Notice that:   awk itself is the “main program.” It does all the work of opening the file, reading the records, separating them into “fields,” and searching for a matching pattern or patterns, which it does from top to bottom in their order of occurrence.

In addition to regular-expression patterns, certain keywords can be used. Any BEGIN block will be executed at the start of the file (for instance to establish the value of RS or record-separator). At the end of the file, the END block, if any, is run.

Within this general framework, any sort of text-file processing task can be very-simply handled, and you may (or, may not...) find it more expedient to do so than with Perl.

If you anticipate that the task might grow beyond what awk is designed to do, then you should probably select Perl from the outset. But for other tasks, IMHO, awk is “just the ticket.” In any case, I find it useful to know about this tool in addition to the Perl approaches given here, and I say you should definitely include it in your toolkit.