Shell Programming and Scripting

#!/usr/bin/perl -w

$file="test.txt";

print "Enter search string : ";
$str=<STDIN>;
chomp $str;

open(FH,$file) || die "Unable to open $file : $!\n";

my $line;
my $strt_str=0;
my @arr=();
my $fnd = 0;

while ( $line = <FH> )
{
        chomp $line;

        if( $line =~ /^header/  ) {
                print join("\n",@arr)."\n" if $fnd == 1;
                @arr = ();
                $strt_str = 1;
                $fnd = 0;
        }

        push(@arr,$line) if( $strt_str == 1 );

        $fnd = 1 if ( $line =~ /$str/ );

        $strt_str = 0 if ( $line =~ /^footer/ );
}

print  join("\n",@arr)."\n";

awk ' BEGIN { RS = "" ; FS = "\n" }
{ flag=0;
for( i = 1 ; i <= NF; ++i )
{
if(match ( $i , "^xy$" ))
        {  flag=1;break;  }
}
if( flag == 1 ) print
} ' file

header
xxyy
lmno
xxyy
wxyz
footer

header
abcd
pqrs
footer

header
fklsdjsdfalgj
xy
sd;lfks;lkfsd
footer

import re
data = open("input.txt").read()
pattern = re.compile(r"header(.*?)footer",re.M|re.DOTALL)
for i in pattern.findall(data):
 	if i.find("xy") != -1:
 		print i

xxyy
lmno
xxyy
wxyz


fklsdjsdfalgj
xy
sd;lfks;lkfsd