How to lock files (the easiest/best way)?

[Elmo Mäntynen]

On Sat, 15 Jul 2006 23:28:21 +0200, Sybren Stuvel wrote:

> Elmo Mäntynen enlightened us with:
>> Is there something better than using fnctl? It seems a bit
>> intimidating with a quick look.
> 
> Locking files is a complex business. What do you want to lock? Why?
> Lock it with respect to what? It's easier to lock a file for local
> use, compared to when the file also has to be locked from, say, use
> via the network.
> 
> Sybren

Only locally. I want to be able to read/write to a single file from
multiple possibly parallel processes. Would 'touch lock' (or something
like that) work reliably (this just occured to me)?