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List:       cgi-list
Subject:    Re: [CGI] Parsing Large Files
From:       Michael Dabrowski <michael () dabrowski ! org>
Date:       1998-11-24 17:47:37
[Download RAW message or body]

At 07:01 PM 11/23/98 -0800, you wrote:
>I have the same problem and WOULD LOVE to know the answer!

Here's a simple script to solve the problem:

#!/usr/bin/perl

=head1

 Program reads a specified $file, a character at a time using sysread()
with allows for sequential reading, without neding to have the whole
file stored in memory. Function fd_read() accepts as its arguments a
pointer to a file handle, and to an output variable which will store the
result. fd_read() cuts off reading after sysread finds a '\n' or a '\r'
character. This would account for the behavior of the normal functioning
of the <> operator but without the memory overhead. fd_read() returns
the line read by reference.

=cut1

$file = "/home/user/file";

open(IN, "$file");
while(&fd_read(\*IN, \$buf)) {
        print "$buf\n";
}

sub fd_read {
        local($fd) = shift;             ## Accept File Handle
        local($line) = shift;           ## Accept output line
        local($c);                      ## character place holder
        local($loop) = 0;               ## looping flag
        $$line = "";                    ## Reset line to null
        while(!($loop)) {
                sysread($fd, $c, 1);    ## Read a character from
filehandle
                if($c eq "")            ## If none was read, error.
                { return 0; }           ## Return nothing if error or
eof
                elsif(($c eq "\n") || ($c eq "\r"))
                { $loop = 1; }          ## If character a \n|\r, end
loop
                else { $$line .= $c; }  ## Append character to line
        }
        return 1;
}
------

Hope it helps.

- Michael Dabrowski



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