[ale] flock

[James P. Kinney III]

Hmm. I am specifically pulling password data out of /etc/shadow to
synchronize multiple machines to a master repository. I _really_ don't
want the shadow file changing on any of the machines during the
process.

I've been trying to avoid the ldap or NIS process but it looks like that
is the only well supported route to go on from here. 

On Mon, 2007-03-26 at 08:45 -0400, cfowler wrote:
> On Mon, 2007-03-26 at 08:35 -0400, cfowler wrote:
> > Isn't flock advisory locking?  Maybe vipw uses it?  In order for it to
> > work both programs must use flock.
> 
> vipw does not use flock
> 
> open("/etc/ptmptmp", O_WRONLY|O_CREAT|O_LARGEFILE, 0600) = 3
> link("/etc/ptmptmp", "/etc/ptmp")       = 0
> unlink("/etc/ptmptmp")                  = 0
> open("/etc/passwd", O_RDONLY|O_LARGEFILE) = 4
> read(4, "root:x:0:0:root:/root:/bin/bash\n"..., 8192) = 1414
> write(3, "root:x:0:0:root:/root:/bin/bash\n"..., 1414) = 1414
> read(4, "", 8192)                       = 0
> close(4)                                = 0
> close(3)                                = 0
> stat64("/etc/ptmp", {st_mode=S_IFREG|0600, st_size=1414, ...}) = 0
> clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|
> SIGCHLD, child_tidptr=0xf70f5b08) = 4651
> 
> Instead it creates a temp file and if it exists that is the "lock".
> 
> 
> 
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-- 
James P. Kinney III          
CEO & Director of Engineering 
Local Net Solutions,LLC        
770-493-8244                    
http://www.localnetsolutions.com

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7
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