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Re^2: Temp file strategy

by chb (Deacon)
on Sep 19, 2005 at 06:55 UTC ( #493092=note: print w/replies, xml ) Need Help??

in reply to Re: Temp file strategy
in thread Temp file strategy

This is an interesting feature, but how can a user download such a file? If I understand perldoc -f open correctly, this syntax gives you a filehandle to an anonymous temporary file. Will you need some sort of streaming or some webserver trickery to let the user access this file from outside the perl script?

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Re^3: Temp file strategy
by blazar (Canon) on Sep 19, 2005 at 09:59 UTC
    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
    but of course it is soon deleted:
    $ perl -le 'open $f, "+>", undef; print readlink "/proc/self/fd/" . fileno $f' /tmp/PerlIO_vJg2Uf (deleted)
    $ perl -le 'open $f, "+>", undef; print readlink "/proc/self/fd/" . fileno $f' /tmp/.nfs0004821b00000353
    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.

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