http://qs321.pair.com?node_id=1214772


in reply to Re^5: Getting lines in a file between two patterns
in thread Getting lines in a file between two patterns

Hi,

How can I get only the first/nth set of pattern matched lines.

INPUT __DATA__:

XXXX
YYYY
START
These are the first
set of lines
which are to be extracted
END
START
These are the second
set of lines
which are to be extracted
END
XXX
ZZZ
YYY
START
These are the third
set of lines
which are to be extracted
END
aasds
tteret
tertetr
[download]

[download]

OUTPUT:

These are the first
set of lines
which are to be extracted

[download]

2018-05-18 Athanasius added code and paragraph tags

Replies are listed 'Best First'.
Re^7: Getting lines in a file between two patterns
by poj (Abbot) on May 17, 2018 at 19:54 UTC

    Store the sets of lines in an array of arrays (AoA)

    #!/usr/bin/perl
use strict;

my $flag  = 0;
my @lines = ();
my @set   = ();

while (<DATA>){
  if (/^\s*END/){
    $flag = 0;
    push @set,[@lines];
  } elsif (/^\s*START/){
    $flag = 1;
    @lines = ();
  } elsif ($flag) {
    push @lines,$_;
  }
}

my $n = 1; # first set
print join '',@{$set[$n-1]};

$n = 3; # third set
print join '',@{$set[$n-1]};

__DATA__
XXX
YYYY
START
These are the first
set of lines
which are to be extracted
END
START
These are the second
set of lines
which are to be extracted
END
XXX
ZZZ
YYY
START
These are the third
set of lines
which are to be extracted
END
aasds
tteret
tertetr

    [download]
    poj
[reply]
[d/l]

In Section Seekers of Perl Wisdom