safe simultaneous file append?

[Dale Strickland-Clark]

piet at cs.uu.nl wrote:

>>>>>> Dale Strickland-Clark <dale at riverhall.NOSPAMco.uk> (DS) writes:
>
>DS> Yes. You can't append to a file from two different places at once. You
>DS> have a few choices:
>
>In fact in modern Unixes you *CAN*.
>From man fopen:
>
>     Opening a file with append mode (a as the first character in
>     the  mode argument) causes all subsequent writes to the file
>     to be forced to the then current end-of-file, regardless  of
>     intervening  calls  to fseek(3S).  If two separate processes
>     open the same file for append, each process may write freely
>     to  the file without fear of destroying output being written
>     by the other.  The output from the  two  processes  will  be
>     intermixed in the file in the order in which it is written.

Erk! There's a recipee for disaster unless treated very carefully. 

Handy if you're careful, though, I guess.
--
Dale Strickland-Clark
Riverhall Systems Ltd