[CPMD-list] Upon compilation of cpmd2cube...

[Axel Kohlmeyer]

On Thu, 27 May 2004 kohsj at ihpc.a-star.edu.sg wrote:

AK> Dear Dr. Axel,
AK> 

AK> Is there any way that one can remove the .nfsXXXXX files, and
AK> subsequently, the "cpmd2cube-v0.1.1" folder?

the explanation should have made it clear, that you simply
have to terminate _all_ processes accessing files in that directory,
including editors, file viewers, file managers, directory browsers etc.

axel.

AK> 
AK> Thanks again!
AK> 
AK> 
AK> 
AK> AK> My IT man suggested that it could probably be:
AK>  AK> 
AK>  AK> 
AK>  AK> "Since you are the one who create the folder, you shall have the 
AK>  right to
AK>  AK> remove anything in the folder. However, you claim that you 
AK>  delete the
AK>  AK> file and it come back again. This is mostly likely due to your 
AK>  program.AK> You may have write a program and this program may need 
AK>  to write
AK>  AK> something in this folder everytime it is running and therefore 
AK>  the file
AK>  AK> come back after you delete it. I just make a guess and I do not 
AK>  have any
AK>  AK> evidence to support my point. Hope that clear your doubt."
AK>  
AK>  well, this is close to the explanation. the reason for the .nfsXXXXX 
AK>  filesis 'feature' of NFS in order to emulate posix style file access 
AK>  semantics.to explain: if you delete a file on a posix/unix machine, 
AK>  the file is
AK>  initially only removed from the directory listing but not deleted if 
AK>  thereis still a process, that has an open file descriptor pointing 
AK>  to that
AK>  file. only if the last process accessing the file has ended, that 
AK>  file is
AK>  really deleted. this is btw a very convenient way of creating 
AK>  'invisible'scratch files, that get automatically deleted, when the 
AK>  process terminates
AK>  or dies (you open(2)/fopen(3) a file with a unique name for writing 
AK>  and 
AK>  immediately unlink(2) it). back to the .nfsXXXX file: the NFS 
AK>  filesystem,however is basically 'stateless', i.e. the connection to 
AK>  the NFS server 
AK>  can be interrupted any time and later reconnected (in some cases it 
AK>  can 
AK>  even survive an intermediate reboot with replacing the hardware and 
AK>  resizing the filesystem). so to implement the 'file-stays-even-if-
AK>  deleted'semantics, the nfs server daemon acts as a proxy for the 
AK>  processes 
AK>  accessing the file, but to make this work even in case of a reboot, the
AK>  .nfsXXXX files are created. the XXXXX is an hash, that allows the 
AK>  serverto detect the process needing to access the 'file with no name'.
AK>  most frequently this happens if you open a file in an editor, that
AK>  keeps an open file descriptor to the file it opens (or to the 
AK>  associated backup/undo file).
AK>  
AK>  
AK>  
AK>  axel.
AK> 

-- 


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Dr. Axel Kohlmeyer                        e-mail: axel.kohlmeyer at rub.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
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