Speeding up Tie::File

tcf03 has asked for the wisdom of the Perl Monks concerning the following question:

I have two subroutines

sub get_first
{
    # usage: get_first("firstfile");
    my $f1=shift; # first file
    tie my @file1, 'Tie::File', "$workdir$f1" or die("Can't tie $f1: $
+!\n");
    my $first=@file1[0];
    untie @file1;
    my ($dow, $month, $day, $time, $year, $line)=split(/\s+/, $first);
    my $start_time=join ' ', $month,$day,$year,$time;
    return $start_time;
}

sub get_last
{
    # usage: get_last("lastfile");
    my $f2=shift; # last File
    tie my @file2, 'Tie::File', "$workdir$f2" or die("Can't tie $f2: $
+!\n");
    my $last=@file2[$#file2];
    untie @file2;
    my ($dow, $month, $day, $time, $year, $line)=split(/\s+/, $last);
    my $end_time=join ' ', $month,$day,$year,$time;
    return $end_time;
}
[download]

and they are called like this:

$rfmain_beg=&get_first($rfmain[0]);
$rfmain_end=&get_last($rfmain[$#rfmain]);
[download]

where @rfmain holds a list of file names. The problem is that this takes a very long time, the files are about 120 - 220 meg each. I just need the very first line of the first file and the very last line of the last file. These are log files and each line begins with a date. Is there a better way of doing this? Ive looked around, but Tie::File seems to be mentioned quite a bit.

Thanks in advance
Ted

UPDATE
Thanks using File::ReadBackwards worked nicely.

Comment on Speeding up Tie::File Select or Download Code

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Re: Speeding up Tie::File by dragonchild (Archbishop) on Apr 11, 2005 at 17:54 UTC
There is no reason for Tie::File. That's for when you want to make modifications in the middle of a file. You have the exact opposite need. `sub get_first_line { my ($filename) = @_; open my $fh, '<', $filename or die "Cannot open '$filename' for reading: $!\n"; return scalar <$fh>; } use File::ReadBackwards; sub get_last_line { my ($filename) = @_; my $fh = File::ReadBackwards->new( $filename ) or die "Cannot open '$filename' for reading backwards: $!\n"; return $fh->readline; }` [download] My wife's blog	[reply] [d/l]

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Re: Speeding up Tie::File
by dragonchild (Archbishop) on Apr 11, 2005 at 17:54 UTC

Tie::File

sub get_first_line {
    my ($filename) = @_;

    open my $fh, '<', $filename
        or die "Cannot open '$filename' for reading: $!\n";
    return scalar <$fh>;
}

use File::ReadBackwards;
sub get_last_line {
    my ($filename) = @_;

    my $fh = File::ReadBackwards->new( $filename )
        or die "Cannot open '$filename' for reading backwards: $!\n";

    return $fh->readline;
}
[download]

My wife's blog

[reply]
[d/l]