• first read in the whole file and then process it line by line
• doing a similar tes ttwice, when one will do

I'd just do

while(<FH>) {
    push @required, $_ if /^abcde.*partname$/;
}
[download]

while(<FH>) {
    print C if /^abcde.*partname$/;
}
[download]

c:\> perl -n -e "print if /^abcde.+PARTNAME$/" c:\somefile.txt>k:\1\so
+mefile.txt
[download]

c:\> perl -n -e "print if /^abcde/ && /PARTNAME$/" c:\somefile.txt>k:\
+1\somefile.txt
[download]

substr()

c:\> perl -n -e "print if substr($_,0,5) eq q(abcde) && substr($_,-9) 
+eq qq(PARTNAME\n)" c:\somefile.txt>k:\1\somefile.txt
[download]

I recommend looking at substr and (if on Unix) the egrep utility, too.

---

Caution: Contents may have been coded under pressure.

Thanx for answer but now have to make a small change
I only want to extract the lines on condition that the
line directly above it starts and ends with the
following 5 chararacters "xyzdf"
basically looking for 2 line match
thanx

Instead of @required and @all and the foreach:

while (<FH>)
{
  print C $_ if /^abcde.*PARTNAME$/;
}
[download]

my $re = qr/^$start.*$end$/;
while (<FH>)
{
  print C $_ if m/$re/;
}
[download]

my $startre = qr/^$start/;
my $endre   = qr/$end$/;
while (<FH>)
{
  print C $_ if m/$startre/ and m/$endre/;
}
[download]

open INFI, "c:\\input\\file.txt" or die "cant open infile: $!\n";
open OUTFI, ">c:\\output\\file.txt" or "cant open outfile : $!\n";

while (<INFI>) {
print OUTFI  if /^abcde.*partname$/;
}
[download]

Please remember that @all=<FH>; will read the entire file into memory. Safe for small files but might cause you grief with huge files.

I think this takes less time for process
If U wish please try this

undef $/;
open (FH, "D:\\temp.txt") || die "Couldn't  open file: $!";
@required=();
$str=<FH>;
close(FH);
(@arr)=$str=~m#(abcde.*?PARTNAME)#gsi;
print "$_\n" for @arr;
[download]