The very easiest way of doing this is to use Tie::File. It allows you to treat the whole files as an array of lines without requiring the whole file to be in memory.

It effectively does the telling and seeking for you and adds in intelligent buffering to boot.

There are two approaches.

1. Read the entire file into memory. (E.g., as an array of lines.) You get rapid access to arbitrary lines.

   my @lines = <FILE>; will read from an open file handle into an array.

2. If the file can't fit in memory (or you choose not to read it all in at once), use tell() to remember interesting places, and seek() to get you back there. They're covered in perlfunc.

Update: tilly pointed out that it's also possible to re-read the file. You can do that by closing and reopening the file (which assumes that the file hasn't been rewritten in the interim), or you can rewind the file handle.

Thanks for your tips...It looks like now I am really close to solving the problem...Just one glitch... I have used the "tell" function to store the location of interest...and then I use the "seek" function to take me there...When I then try to read using $line=<FILE>, I am able to read the next line following the line I actually want....Can u please provide any input on this...

When I then try to read using $line=<FILE>, I am able to read the next line following the line I actually want...

Do the tell() before you read the line. Otherwise, as you've noticed, you're one line too late.

Hers' a sample implementation

my @line_offsets;
push @line_offsets, tell *FOO;
while (my $line = <FOO>) {
    push @line_offsets, tell *FOO;

    if ( foobar() ) {
        seek *FOO, $line_offsets[29];
    }
}
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