Beefy Boxes and Bandwidth Generously Provided by pair Networks
Just another Perl shrine
 
PerlMonks  

Re: get n lines before a pattern

by VinsWorldcom (Vicar)
on Jul 25, 2012 at 14:43 UTC ( #983673=note: print w/ replies, xml ) Need Help??


in reply to get n lines before or after a pattern

Note you're output is not only showing 2 lines before the pattern, but also 1 line AFTER the pattern.

You don't need Perl for something that simple:

grep -B2 -A1 jack test.txt

UPDATE: Since the OP updated the original question, this approach is no longer valid. See my reply (Re^3: get n lines before a pattern) below.


Comment on Re: get n lines before a pattern
Download Code
Re^2: get n lines before a pattern
by darklord_999 (Acolyte) on Jul 25, 2012 at 14:55 UTC
    I have updated the details of my file. Please see the change . Sorry for the previous error.

      Yes, the changes to the file in the OP certainly require an updated approach. What have you tried?

      I would loop through the file saving each key and either pushing to a data structure if the name matches or resetting and continuing.

      Pseudo code for the loop and structure I'd use:

      my @matches; my $FOUND = 0; my %info = {}; while (<INFILE>) { chomp $_; if (($_ =~ /^id/) and ($FOUND)) { push @matches \%info; $FOUND = 0; %info = {} } if ($_ =~ /^id/) { (undef, $info{id}) = split / /, $_} if ($_ =~ /^address/) { (undef, $info{address}) = split / /, $_} if ($_ =~ /^name/) { (undef, $info{fname}) = split / /, $_} ... if ($searchPattern eq $info{fname}) { $FOUND = 1; } }

      UPDATE: Added 'chomp' and updated 'split' commands as per kennethk suggestions to me.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://983673]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others imbibing at the Monastery: (4)
As of 2015-07-03 03:44 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (48 votes), past polls