Perl regex matching multiple multiline groups

Question

I have bunch of text and I am trying to match a group of pattern, the regex which I am using is able to match the pattern but the problem is that it matches only the second group not the first group.

open(FILE, "match.txt") || die("Could not open file ");
my $text = do { local $/; <FILE> };

while( $text =~ m/FibreChannel SCSI Interface.*World Wide Port Number\.*(.*?)\n.*Driver\.+(.*?)\n.*Vendor Name\.+(.*?)\n/sgmp )
{
    print "$1\n$2\n$3\n";
}

Prints

0x1b201
lpfc_740
Test Corporation

The above code works but it displays only the text from the second group not the first group. What am I missing here? Is there a better way to do this?

I thought it would print

0x1a101
lpfc_740
Test Corporation
0x1b201
lpfc_740
Test Corporation

------------------------ match.txt contains

\==+FibreChannel SCSI Interface : 
        |----Link State.........................................Down
        |----World Wide Port Number.............................0x1a101
        \==+SCSI Interface : 
           |----Driver..........................................lpfc_740
           |----Queue Depth.....................................2038 
           \==+PCI Device : 
              |----Bus..........................................0x06 
              |----Vendor Name..................................Test Corporation
              |----Slot Description.............................

\==+FibreChannel SCSI Interface : 
        |----Link State.........................................Down
        |----World Wide Port Number.............................0x1b201
        \==+SCSI Interface : 
           |----Driver..........................................lpfc_740
           |----Queue Depth.....................................2038 
           \==+PCI Device : 
              |----Bus..........................................0x0a 
              |----Vendor Name..................................Test Corporation
              |----Slot Description.............................

ruakh · Accepted Answer · 2012-03-14 20:34:00Z

5

The problem is that the first .* is greedily matching as much as it can without preventing a match; so, it swallows everything up until the second World Wide Port Number. You need to change it to .*?, like you're already using elsewhere in your pattern. (And, similarly for other instances of .*.)

edited Mar 14, 2012 at 20:34

answered Mar 14, 2012 at 20:22

ruakh

185k29 gold badges292 silver badges324 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Sumedh Over a year ago

I changed .* to .*? for all the instances and now I get the first group not the second group. I still cannot figure out why I cannot get both the groups.

ruakh Over a year ago

Are you sure you've changed it in all three places? Since your $2 and $3 look the same in both groups, leaving .* intact in just one place will make it look like only the first group is being matched, when in fact, your regex is really matching both groups together.

Sumedh Over a year ago

ruakh, you are a god among men. Thanks it worked, I knew I was doing some silly mistake but could not figure out what.

user966588 · Accepted Answer · 2012-03-14 21:03:30Z

0

Here's how it should be

$text =~ m/FibreChannel SCSI Interface.*?World Wide Port Number\.*([a-z0-9]+).*?Driver\.+(\w+).*?Vendor Name\.+([a-zA-Z ]+).*?\n/sgmp

answered Mar 14, 2012 at 21:03

user966588

1 Comment

Sumedh Over a year ago

Thanks Devendra, this works too, I added ruakh's comments in my code and now its working.

Collectives™ on Stack Overflow

Perl regex matching multiple multiline groups

2 Answers 2

3 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related