Now that you have your answer, I wonder if you'd care to suggest how we could improve the documentation for open to make it more obvious how to solve your problem. Currently the docs say this:

You can put a '+' in front of the '>' or '<' to indicate that you want both read and write access to the file; thus '+<' is almost always preferred for read/write updates--the '+>' mode would clobber the file first.

open my $handle, "+<", "/your/file/here" or die "Failed to open file: 
+$!";
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Take a look at Modify file without any temp variable

Thanks
Gopal.R

Excellent this is just what I was looking for Thanks

open(FH, "+<", "$filename") or die "Opening: $!";
@ARRAY = <FH>;
# change ARRAY here
seek(FH,0,0) or die "Seeking: $!";

    for($i=0;$i<=$#ARRAY;$i++)
    {
        $line = $ARRAY[$i];
        $line=~s#find#replace#;
        $ARRAY[$i] = $line;
    }

print FH @ARRAY or die "Printing: $!";
truncate(FH,tell(FH)) or die "Truncating: $!";
close(FH);
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regards
Franklin

Minor nit, but a C-style for loop like that is really unnecessary here. You can do:

for $elem (@ARRAY)
{
    $elem =~ s#find#replace#;
}
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Or even more concisely:

s#find#replace# for @ARRAY;
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Do not rebuke them with harsh words ... but rather lead them gently - with URLs - so that they may learn wisdom.

If you are simply passing through the file editing it then a common Perl idiom is to use inplace edit thus:

local @ARGV = ('nameOfFileToEdit');
local $^I = '.bak'; # extension for backup version of file

while (<>)
    {
    #line read is in $_
    print "new state of line\n"; # write updated line
    }
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you can put a ’+’ in front of the ’>’ or ’<’ to indicate that you want both read and write access to the file; thus ’+<’ is almost always preferred for read/write updates--the ’+>’ mode would clobber the file first. You can’t usually use either read-write mode for updating textfiles, since they have variable length records.

The most important thing when you open file in both the modes is you have to use the "seek" functions effectively. Wrong read/write operation leads to data loss or it will create holes in the files.