This sounds an easy task, but I'm certain that I'm yet to find the most 
elegant solution.

I have a text file which I want to process using ruby in order to update 
it.  I want to remove the single line which matches a regexp for which I 
have a definition.  I'd prefer not to explicitly use temporary files - 
however (and this is important) I also don't want to risk loosing data 
with corruptions if the ruby process is killed unexpectedly... and I 
definitely don't want a file other than the one with/without the line 
I'm deleting to be read by any other process.

Is there something in a library which would make this task easy?