What is the best way to copy a file to a temporary file?

(The purpose of the temporary file is to read data from, process it in some way, and then write it back over the top of the original file; i.e. I effectively want to edit the original file "in-place", but not all in memory at once in case it is too large.)

I was intending to use the File::Temp::tempfile() function to get a temporary file, and File::Copy to do the copying, but both of the following obvious ideas have problems: 

  1. my $tmpfh = File::Temp::tempfile();
File::Copy::copy($file, $tmpfh);

    [download]
  2. my($tmpfh, $tmpfile) = File::Temp::tempfile(UNLINK => 1);
File::Copy::copy($file, $tmpfile);

    [download]
The first idea is risky according to File::Copy's manpage (it says passing filehandles instead of filenames to copy() may lead to loss of information on some systems), while the second idea is not the recommended practice in File::Temp's manpage (it is safer to only get the temporary file's filehandle, not to get it's name as well).

In reply to Copying a file to a temporary file by shay

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