arootbeer has asked for the wisdom of the Perl Monks concerning the following question:

Fellow monks, is there a quick analogue to grep -p using regexp? I'm currently using a 

next if ...
statement because I have a specific case that I'm looking for, but I'd like a more general and robust way of getting information on lines that are related to a target line by proximity.

Does perl's built-in grep function support such functionality?

Thanks!

-Matt

Replies are listed 'Best First'.
Re: grep -p ?
by Abigail-II (Bishop) on Dec 09, 2003 at 17:12 UTC
    Could you explain what grep -p is supposed to do? The GNU implementation of grep doesn't know about -p.

    Abigail

[reply]
      in AIX, grep -p will grab the paragraph surrounding a line. for instance, grep -p "lazy" on 
      the quick
red fox

jumped over
the lazy
brown dog.
      will return the last 3 lines, 
      jumped over
the lazy
brown dog.
[reply]
        Just turn on paragraph mode then. 
        #!/usr/bin/perl

use strict;
use warnings;

$/ = "";  # Paragraph mode.

while (<DATA>) {
    print if /lazy/;
}

__DATA__
the quick
red fox

jumped over
the lazy
brown dog.





jumped over
the lazy
brown dog.

        [download]

        Abigail

[reply]
[d/l]

        Hmm. Sounds like he should just slurp his file in paragraph mode, or if he has an array, stringify it and slurp it in paragraph mode.

        A one-liner ...

        perl -000 -ne 'print if /lazy/' lazy_file

        [download]

        See Abigail's non-one-liner too.

        Update: When I wrote

        stringify it and slurp ... in paragraph mode
        I was thinking of perl's new open-and-read-from-a-scalar, but it appears that it doesn't recognize reading in paragraph mode. Is there any way to make this work:

        # assuming @array already exists for some reason
$str = join "", @array;
open S, "<", \$str or die;
$/ = "";                     # paragraph mode normally
while (<S>) {
   print if /lazy/;
}
close S;

        [download]

        Or is this a bug? (I'm using perl 5.8.0)

        PerlJam

[reply]
[d/l]
[select]
Re: grep -p ?
by Anonymous Monk on Dec 09, 2003 at 17:24 UTC
    Does perl's built-in grep function support such functionality?
    Did you read the docs for perl's built-in grep function ?
[reply]

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