Indeed. But it depends on the OS you're under: I'm not really sure, but I think that Windows doesn't support real anonymous files, so the temporary file that you can see should still be there somewhere.

Here I'm under Linux and I get 

$ strace -e open perl -e 'open $f, "+>", undef' 2>&1 | tail -n 1
open("/tmp/PerlIO_vfNALU", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0600) = 
+3

[download]
but of course it is soon deleted: 
$ perl -le 'open $f, "+>", undef;
print readlink "/proc/self/fd/" . fileno $f'
/tmp/PerlIO_vJg2Uf (deleted)

[download]
(or 
$ perl -le 'open $f, "+>", undef;
print readlink "/proc/self/fd/" . fileno $f'
/tmp/.nfs0004821b00000353

[download]
if run on a machine where /tmp is mounted under nfs.)

Whatever, all this is at best fragile and tricky. This interesting open feature is best suited for a file to write stuff into, to recover it later. For your application any of the other suggestions you got would be probably preferable.

I just mentioned this temp file strategy option because IMHO it would deserve to be better known.

In reply to Re^3: Temp file strategy by blazar
in thread Temp file strategy by Sprad

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.