[NTLUG:Discuss] File Locking

[Leroy Tennison]

Chris Cox wrote:
> Patrick R. Michaud wrote:
>   
>> On Thu, Apr 12, 2007 at 11:12:26PM -0500, Chris Cox wrote:
>>     
>>> Dennis Rice wrote:
>>>       
>>>> A co-worker would like to set up a file as being locked when a user 
>>>> opens it, so that others can not write to the file.  I am not aware of 
>>>> any permission / attribute that can do this.  Anyone have an idea or 
>>>> suggestion?  Appreciate.
>>>>         
>>> Though I don't recommend it... you can open a file with an exclusive
>>> lock on it (an OS wide lock).  However, if you forget to unlock, it
>>> will cause things like your backups to hang since the file is forever
>>> locked.
>>>
>>> man flock
>>>
>>> (you may only have the function call... openSUSE has flock(1))
>>>       
>> To add a bit more information... flock provides "advisory" locking
>> (as opposed to "mandatory" locks).  Advisory locking blocks
>> only those processes that attempt to set a lock with flock --
>> processes that aren't using flock can still open and write to
>> files that are "locked" with flock.
>>
>> Mandatory locks are performed using the fcntl(2) and/or lockf(3)
>> function calls, and yes, if a process uses mandatory locking on
>> a file it can cause problems for other programs that may try
>> to access that file.
>>     
>
> Uh... yes... that's what I meant (my oops).
>
> I was just so happy to see a command line flock!!
>
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>   
Command line flock..., SuSE I take it? (Not on CentOS 4.4).