RE: [ LUGOS-PROG ] tezave z zaklepanjem

[Gregor . Ibic]

Če se že mučite....
                                                                                   
                                                                                   
                                                                                   
                                                                                   
 2.2. File locking in the UNIX/NFS environment                                     
                                                                                   
                                                                                   
 In contrast with Windows, UNIX systems do not support the concept of a deny-mode  
 when accessing a file. This lack of a file locking paradigm can be seen when      
 examining the UNIX system call that performs a similar role to that of the        
 CreatFile() function in the Windows environment:                                  
                                                                                   
      open(char *fname, int mode)                                                  
 Like the CreateFile() function, the open() system call allows a UNIX application  
 to open a file with an access mode that allows reading, writing or both. The      
 application stipulates this access-mode in the mode parameter of the open()       
 function. However, the UNIX operating system does not allow applications to       
 specify a deny-mode when opening a file and, as a consequence, UNIX applications  
 have no true file locking facility available to them. However, even though UNIX   
 systems do not support or expose a file locking facility to applications, the NFS 
 Network Lock Manager (NLM) as implemented on most UNIX systems does contain       
 functionality that allows client systems to take out file locks on NFS file       
 servers. This functionality is normally only used by DOS and Windows based        
 clients that are using a (PC)NFS implementation to access an NFS server. It was   
 needed in order to allow (PC)NFS implementations to support the Windows file      
 locking paradigm on NFS networks. Having no concept of a file lock, UNIX based    
 NFS clients do not make use of this particular aspect of the NLM.                 
                                                                                   
                                                                                   

READ MORE ON:
http://www.netapp.com/tech_library/3024.html#2.2


LP,
Gregor

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