Re: [MacPerl] How to modify a text file

[Ronald J Kimball <rjk@linguist.dartmouth.edu>]

On Tue, Jun 08, 1999 at 10:09:23AM -0400, Ingo Bitsch wrote:
> Another newbie-question:
> 
> What is the standard way of modifying a text file with Perl? I 
> experimented a bit with all the modifiers in front of the filename in the 
> "open"-function, but I always ended up opening the file TWICE: 
> 
> open (IN, "file.txt");
> @all_lines=<IN>;
> $_ = join "",@all_lines;
> 
> #(Do some operations on $_ here)
> 
> open (OUT, ">file.txt");
> print OUT;
> 
> I can't believe that there is no other way of doing it. Another thing 
> that makes me nervous about my approach is that there is a moment in the 
> script (after the second "open") when the contents of my file is alrady 
> erased and lives only in the $_-Variable...
> 

Open for read-write access:


open(FH, "+<file.txt") or die "Unable to open file.txt: $!\n";
{
  local $/;
  $_ = <IN>;
}

#(Do some operations on $_ here)

seek(FH, 0, 0) or die "Unable to seek in file.txt: $!\n";
print FH;


This is mentioned in the documentation for open() in perlfunc.


Ronald

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