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[RESOLVED]how to take the previous line

danielpcorrea
Novice

Apr 6, 2009, 1:26 AM

Post #1 of 3 (1241 views)

[RESOLVED]how to take the previous line	Can't Post

Hi
I'm working with a strange log. It's a mix between timestamp normal log and xml format.

Ex:

20090231175400 | abc | good
20090231175500 | abc | bad
20090231175600 | abc | good
<pb><pms="0123456"></pms></pb>

I need the last timastamp value before the xml row (20090231175600)

My script take the xml line, but I dont know how to take the previous line.

Code

    if ($_ =~ m/pms/) {  
       chomp; 
        $RScont++; 
      }

Can anybody help me?
thanks
Daniel

(This post was edited by danielpcorrea on Apr 7, 2009, 1:42 AM)

KevinR
Veteran

Apr 6, 2009, 9:52 AM

Post #2 of 3 (1230 views)

Re: [danielpcorrea] how to take the previous line [In reply to]	Can't Post

Either cache the previous line in a scalar or use the Tie::File module so you can access the file in the same manner as a perl array. Then the previous line is the index of the current line minus one. See Tie::File for usage. Here is a brief and generic example caching the previous line (untested code):

Code

open(FILE, "thefile") or die "$!"; 
my $pre = <FILE>; #get first line 
while(<FILE>){ 
   if (/pms/) { 
      print $pre; 
      $RScont++;  
   } 
   else { 
      $pre = $_; 
   } 
}

-------------------------------------------------

danielpcorrea
Novice

Apr 7, 2009, 1:41 AM

Post #3 of 3 (1214 views)

Re: [KevinR] how to take the previous line [In reply to]	Can't Post

Thanks.
Works fine.

Daniel

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