Try (Updated:simplified code):

#! perl -sw
use strict;

while( <DATA> ) {
    chomp;
    print "$_ ";
    unless( $. % 3 ) {
        print "\n";
    }
}

__DATA__
array A
physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK
physicaldrive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
array B
physicaldrive 2C:1:3 port 2C:box 1:bay 3 SAS 1 TB OK
physicaldrive 2C:1:4 port 2C:box 1:bay 4 SAS 1 TB OK
array C
physicaldrive 3C:1:5 port 3C:box 1:bay 5 SAS 1 TB OK
physicaldrive 3C:1:6 port 3C:box 1:bay 6 SAS 1 TB OK
array D
physicaldrive 3C:1:7 port 3C:box 1:bay 7 SAS 1 TB OK
physicaldrive 3C:1:8 port 3C:box 1:bay 8 SAS 1 TB OK
[download]

Ouput:

C:\test>junk
 array A physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK physical
+drive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
 array B physicaldrive 2C:1:3 port 2C:box 1:bay 3 SAS 1 TB OK physical
+drive 2C:1:4 port 2C:box 1:bay 4 SAS 1 TB OK
 array C physicaldrive 3C:1:5 port 3C:box 1:bay 5 SAS 1 TB OK physical
+drive 3C:1:6 port 3C:box 1:bay 6 SAS 1 TB OK
[download]

Thanks for the reply . It seems we are combining every 3 lines in to a single line , If I am not wrong . The O/P could even stretch to more than 3 lines after matching array and until it hits the next array string .

The O/P could even stretch to more than 3 lines after matching array and until it hits the next array string

Then it is a good idea to present sample data that shows that.

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use strict;
use warnings;

local $/="\narray ";
while (<DATA>){
    s/\n(?!unassigned)(:?array)?/ /g;
    print  my $row=(m/^array/?"":"array "). "$_\n";
}
__DATA__
array A
physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK
physicaldrive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
array B
... etc ...
unassigned
physicaldrive 7C:3:7 port 7C:box 3:bay 7 SAS 1 TB OK
...
[download]

array A physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK physicald
+rive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK  
array B physicaldrive 2C:1:3 port 2C:box 1:bay 3 SAS 1 TB OK physicald
+rive 2C:1:4 port 2C:box 1:bay 4 SAS 1 TB OK  
... 
array J physicaldrive 6C:3:3 port 6C:box 3:bay 3 SAS 1 TB OK physicald
+rive 6C:3:4 port 6C:box 3:bay 4 SAS 1 TB OK  
array K physicaldrive 7C:3:5 port 7C:box 3:bay 5 SAS 1 TB OK physicald
+rive 7C:3:6 port 7C:box 3:bay 6 SAS 1 TB OK
unassigned physicaldrive 7C:3:7 port 7C:box 3:bay 7 SAS 1 TB OK physic
+aldrive 7C:3:8 port 7C:box 3:bay 8 SAS 1 TB OK
[download]

Hi, Here is the O/P that I needed. I probably skipped few lines in my code during my first post .

use strict;
use warnings;
use Data::Dumper;
my %unitMap;
my $skipNext;
my $count = 0;
my $cmd  = "somecommand";;
open my $fd, "$cmd|" or return \%unitMap;
while (my $row = <$fd>) {
        $row =~ /^$/ and next;
        $row =~  s/[,|)|(]//g;
        chomp $row;
        next if  $row =~ /^Smart/g;
        $row =~ s/^\s+//;
        if( $row =~ /^unassigned/ ){
        $skipNext = 2;
        next;
        }
        if( $skipNext ){
        $skipNext--;
        next;
        }
        print "$ow\n";
[download]

Below is my Data exactly .

 data
array A
physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK
physicaldrive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
array B
physicaldrive 2C:1:3 port 2C:box 1:bay 3 SAS 1 TB OK
physicaldrive 2C:1:4 port 2C:box 1:bay 4 SAS 1 TB OK
array C
physicaldrive 3C:1:5 port 3C:box 1:bay 5 SAS 1 TB OK
physicaldrive 3C:1:6 port 3C:box 1:bay 6 SAS 1 TB OK
array D
physicaldrive 3C:1:7 port 3C:box 1:bay 7 SAS 1 TB OK
physicaldrive 3C:1:8 port 3C:box 1:bay 8 SAS 1 TB OK
array E
physicaldrive 4C:2:1 port 4C:box 2:bay 1 SAS 1 TB OK
physicaldrive 4C:2:2 port 4C:box 2:bay 2 SAS 1 TB OK
array F
physicaldrive 4C:2:3 port 4C:box 2:bay 3 SAS 1 TB OK
physicaldrive 4C:2:4 port 4C:box 2:bay 4 SAS 1 TB OK
array G
physicaldrive 5C:2:5 port 5C:box 2:bay 5 SAS 1 TB OK
physicaldrive 5C:2:6 port 5C:box 2:bay 6 SAS 1 TB OK
array H
physicaldrive 5C:2:7 port 5C:box 2:bay 7 SAS 1 TB OK
physicaldrive 5C:2:8 port 5C:box 2:bay 8 SAS 1 TB OK
array I
physicaldrive 6C:3:1 port 6C:box 3:bay 1 SAS 1 TB OK
physicaldrive 6C:3:2 port 6C:box 3:bay 2 SAS 1 TB OK
array J
physicaldrive 6C:3:3 port 6C:box 3:bay 3 SAS 1 TB OK
physicaldrive 6C:3:4 port 6C:box 3:bay 4 SAS 1 TB OK
array K
physicaldrive 7C:3:5 port 7C:box 3:bay 5 SAS 1 TB OK
physicaldrive 7C:3:6 port 7C:box 3:bay 6 SAS 1 TB OK
unassigned
physicaldrive 7C:3:7 port 7C:box 3:bay 7 SAS 1 TB OK
physicaldrive 7C:3:8 port 7C:box 3:bay 8 SAS 1 TB OK
[download]

a) The Aim here is to join lines starting with string array and until it hits the pattern starting with the string array again and join the lines and repeat the same for all the lines in the string . b) The Line containing unassigned and the lines after it should be removed until it hits a line containing the string array at the start of line . c) In my code , I have removed the line containing unassigned and 2 lines after it , But it should remove any number of lines after unassigned until it matches array at the start of the string .

 data
   unassinged...
   physicaldrive .........
   physical dirve .....
   physicaldrive......
   array
[download]

Slightly simpler logic..

use strict;
use warnings;

my $row ="";
my $inarray=0;
while (<DATA>) {
    chomp;
    if (/^array|^unassigned/){
        print "$row\n" if $inarray;
        $row=$_;
        $inarray=m/^array/;
        next;
    }
    next unless $inarray;
    $row .= " $_";
}
print "$row\n" if $inarray;
__DATA__
....
[download]

        "You're only given one little spark of madness. You mustn't lose it."         - Robin Williams

#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dump;

my $hashRef;
# See Perldoc perldsc
                        
my $lastSeen;               
for (<DATA>) {              
    length or next;         
    chomp;                  
    if (!/^physicaldrive/) {
        $lastSeen=$_;
    } else {
        push @{$hashRef->{$lastSeen}},$_;
    }
}

my @arrayA = @{$hashRef->{'array A'}};
dd @arrayA;

my $secondDiskArrayA = $hashRef->{'array A'}[1];
dd $secondDiskArrayA;

my $unassignedDisks = $hashRef->{unassigned};
dd $unassignedDisks;

dd $unassignedDisks->[0];
[download]

foreach readline slurps, while readline does not slurp :)

I like the following way:

use strict;
use warnings;
use Data::Dumper;
my @data;
while( <DATA> ) {
    chop;
    if ( /^(array.*|unassigned)$/ ) {
        push @data, $1;
    } else {
        $data[-1] .= " $_";
    }
}
print Dumper \@data;
__DATA__
array A
physicaldrive 2C:1:1 port 2C:box 1:bay 1 SAS 1 TB OK
physicaldrive 2C:1:2 port 2C:box 1:bay 2 SAS 1 TB OK
array B
physicaldrive 2C:1:3 port 2C:box 1:bay 3 SAS 1 TB OK
physicaldrive 2C:1:4 port 2C:box 1:bay 4 SAS 1 TB OK
unassigned
physicaldrive 7C:3:7 port 7C:box 3:bay 7 SAS 1 TB OK
physicaldrive 7C:3:8 port 7C:box 3:bay 8 SAS 1 TB OK
[download]

Nice! Except the groups beginning with "unassigned" should not be printed.

1 Peter 4:10

Thanks for the reply . $row is the variable where my Command output file handle is for reading . How do I go about capturing the output in the $row variable as I have trimmed lot of lines in the O/P using the scalar variable .

Thanks for the reply . Tried the same code , But it fails with the Error Below . Modification of non-creatable array value attempted, subscript -1 at ./file2.pl line 15, <$fd> line 1.

This can happen if the data does not start with an "array" line (I am guessing).