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From: Prasanth on 16 Apr 2008 09:06
When a file is open does unlink automatically deletes the file or it
generates an error. Because I wrote a program to delete a file and
regenerate the file. if the file is not deleted the data simply gets
appended to the existing file. which results in wrong results
From: Joost Diepenmaat on 16 Apr 2008 09:21
Prasanth <prasanths89(a)gmail.com> writes:

> When a file is open does unlink automatically deletes the file or it
> generates an error. Because I wrote a program to delete a file and
> regenerate the file. if the file is not deleted the data simply gets
> appended to the existing file. which results in wrong results

Unlink removes inodes, and it should succeed in that even if the file is
opened by any process. It does not empty files, if that's what you mean.


--
Joost Diepenmaat | blog: http://joost.zeekat.nl/ | work: http://zeekat.nl/
From: A. Sinan Unur on 16 Apr 2008 09:25
Prasanth <prasanths89(a)gmail.com> wrote in
news:270a0c78-9d5e-4486-8b35-b429c4d61755
@u36g2000prf.googlegroups.co
m:

> When a file is open does unlink automatically deletes the file or
> it generates an error. Because I wrote a program to delete a file
> and regenerate the file. if the file is not deleted the data
> simply gets appended to the existing file. which results in wrong
> results

Hmmmm ... What is the question?

If you script opened the file, close it before calling unlink.

If the file is opened in exclusive mode by another process, I am not
sure deleting it is the correct action in the first place.

If you don't want your script to continue if unlink failed, you
should check the return value of unlink.

On the other hand, not that this will solve whatever problem you are
having, I would not have messed with unlink at all:

open my $out_h, '>', 'report.txt'
or die "Cannot open 'report.txt': $!";

That truncates the file if it can be opened and would die if it
cannot. Beats appending junk to a file.

There are just two many combinations of problems and solutions that
might apply to your post. Please elaborate after reading the posting
guidelines for this group and may be taking a look at the following
page:

http://blogs.msdn.com/oldnewthing/archive/2008/04/15/8397753.aspx

Sinan

--
A. Sinan Unur <1usa(a)llenroc.ude.invalid>
(remove .invalid and reverse each component for email address)

comp.lang.perl.misc guidelines on the WWW:
http://www.rehabitation.com/clpmisc/
From: A. Sinan Unur on 16 Apr 2008 09:29
Joost Diepenmaat <joost(a)zeekat.nl> wrote in
news:87hce2gcko.fsf(a)zeekat.nl:

> Prasanth <prasanths89(a)gmail.com> writes:
>
>> When a file is open does unlink automatically deletes the file or
>> it generates an error. Because I wrote a program to delete a file
>> and regenerate the file. if the file is not deleted the data
>> simply gets appended to the existing file. which results in wrong
>> results
>
> Unlink removes inodes, and it should succeed in that even if the
> file is opened by any process. It does not empty files, if that's
> what you mean.

I am guessing the OP is on Windows where

http://windowshelp.microsoft.com/Windows/en-US/help/47b3ce2b-3aec-401d-8be3-74434a1999831033.mspx

Sinan

--
A. Sinan Unur <1usa(a)llenroc.ude.invalid>
(remove .invalid and reverse each component for email address)

comp.lang.perl.misc guidelines on the WWW:
http://www.rehabitation.com/clpmisc/
From: Ben Morrow on 16 Apr 2008 09:56

Quoth Joost Diepenmaat <joost(a)zeekat.nl>:
> Prasanth <prasanths89(a)gmail.com> writes:
>
> > When a file is open does unlink automatically deletes the file or it
> > generates an error. Because I wrote a program to delete a file and
> > regenerate the file. if the file is not deleted the data simply gets
> > appended to the existing file. which results in wrong results
>
> Unlink removes inodes, and it should succeed in that even if the file is
> opened by any process. It does not empty files, if that's what you mean.

Unlink removes *filenames*. Inodes are refcounted, and self-destruct
when there are no refs to them (including open file descriptors).

This only applies to Unixish filesystems, of course. Win32 won't let
you unlink an open file (under normal circumstances).

Ben

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