Count the lines in the file ( how to do this is documented in perlfaq ), subtract 20000 from that number and put the result in $start_at, then open the logfile for reading, incrementing the counter for each line read in and ignore until you've hit $start_at ...

Or ... 75MB is not *that* huge these days. You could load the whole file into memory and just grab the last 20000 lines, e.g. 

# get_last returns an array reference for efficiency,
# so we need to de-reference; hence the @{} around
# the subroutine call 
my @lines = @{ get_last("foo.log", 20000) };

sub get_last {
 my ($filename, $from_last) = @_;
 open FILE, $filename or die "Can't open $filename: $!\n";
 my @lines = <FILE>; #loads the whole thing into memory
 close FILE;
 
 # return the last $from_last lines in an anonymous array
 # $#array_name is the index of the last element of 
 # the array, so @lines[$#lines-20, $#lines] is the
 # last 20 elements of @lines
 [ @lines[$#lines-$from_last, $#lines] ];
}

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HTH

Philosophy can be made out of anything. Or less -- Jerry A. Fodor

In reply to Re: How can I read just the end of a huge file? by arturo
in thread How can I read just the end of a huge file? by vonman

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