Your data appears to be tabular in fixed-width columns so consider using unpack rather than regular expression captures. See pack for a description of how to construct a template to extract your data items.

Hei JohnGG

Better don't spend your time repeating this, we already preached it!

And the OP got brilliant answers with excellent code snippets. =)

--> How we can do regex of this?

@xMiDgArDx: please clarify your problem better, and use code tags there too. And in the future please link to older discussions about the same topic to avoid loss of energy.

Cheers Rolf

my $block=0;
 
while (<DATA>){
  if (!/^\s*$/) {
    print "$block: $_";
  } else {
    $block++;
  }
}
 
__DATA__
Mod Ports Card Type                              Model              Se
+rial No.
--- ----- -------------------------------------- ------------------ --
+---------
  1   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP       SA
+L1434RA09
  3   20  7600 ES+T                              76-ES+T-20G        JA
+E14530455
  4   ...
  
Mod  Sub-Module                  Model              Serial       Hw   
+  Status
---- --------------------------- ------------------ ----------- ------
+- -------
  1  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1434RLPY  1.6  
+  Ok
  3  7600 ES+ DFC XL             7600-ES+3CXL       JAE14520N29  1.2  
+  Ok
  5  ...
[download]

now you can delegate the rest to specific one-block solution(s).

With the risk of good money after bad and acknowledging that this could have the (your prefered afterlife paradigm here) golfed out of it. I submit the following column split using named captures for each column.

Update: fixed the position split. Requires perl 5.10 or higher.

A slightly more extensible version with a complete dispatch array implementation matched to named capture regular expressions for the columns. (Use the same data file.)

Read more... (2 kB)

Update: removed un-needed variable declarations, still requires perl 5.10 or higher

#!perl

my @lens;
while (<DATA>) {
    /\S/ || next;

    my $pos   = tell(DATA);
    my $nline = <DATA>;
    if ($nline =~ /-/ && $nline =~ /^[-\s]+$/) {
        @lens = map { length() + 1 } split(' ', $nline);
        next;
    }
    else {
        seek DATA, $pos, 0;
    }

    my @values = map { s{^\s+}{}; $_ } unpack(join('', map { "A${_}" }
+ @lens), $_);
    if (@lens == 5) {
        print "================= IF 1 =================\n";
        print "SLOT: $values[0]\n";
        print "PORTAS: $values[1]\n";
        print "DESC: $values[2]\n";
        print "Model: $values[3]\n";
        print "Sw: $values[4]\n";
        print "\n";
    }
    elsif (@lens == 6) {
        print "================= ELSIF =================\n";
        print "<> Slot: $values[0]\n";
        print "<> Desc: $values[1]\n";
        print "<> Model: $values[2]\n";
        print "<> Sw: $values[3]\n";
        print "<> Hw: $values[4]\n";
        print "<> Status: $values[5]\n";
        print "\n";
    }

}
close(DATA);

__DATA__
Mod Ports Card Type                              Model              Se
+rial No.
--- ----- -------------------------------------- ------------------ --
+---------
  1   24  CEF720 24 port 1000mb SFP              WS-X6724-SFP       SA
+L1434RA09
  3   20  7600 ES+T                              76-ES+T-20G        JA
+E14530455
  5    2  Route Switch Processor 720 (Active)    RSP720-3CXL-GE     JA
+E14330N9B
  6    2  Route Switch Processor 720 (Hot)       RSP720-3CXL-GE     JA
+E14330NA6
  7    4  CEF720 4 port 10-Gigabit Ethernet      WS-X6704-10GE      SA
+L1433QVJQ
  8    4  CEF720 4 port 10-Gigabit Ethernet      WS-X6704-10GE      SA
+L1433QVJW

Mod  Sub-Module                  Model              Serial       Hw   
+  Status
---- --------------------------- ------------------ ----------- ------
+- -------
  1  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1434RLPY  1.6  
+  Ok
  3  7600 ES+ DFC XL             7600-ES+3CXL       JAE14520N29  1.2  
+  Ok
  3  7600 ES+T 20x1GE SFP        76-ES+T-20GQ       JAE145301XM  1.1  
+  Ok
  5  Policy Feature Card 3       7600-PFC3CXL       JAE14330E6J  1.1  
+  Ok
  5  C7600 MSFC4 Daughterboard   7600-MSFC4         JAE14320QBE  1.6  
+  Ok
  6  Policy Feature Card 3       7600-PFC3CXL       JAE14330EAO  1.1  
+  Ok
  6  C7600 MSFC4 Daughterboard   7600-MSFC4         JAE14320QA8  1.6  
+  Ok
  7  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1433QHBR  1.6  
+  Ok
  8  Distributed Forwarding Card WS-F6700-DFC3CXL   SAL1433QXF9  1.6  
+  Ok
[download]