Is there a good way to implement file updating? such as lock, update, reload...

[Evan]

Hello -

My script use a DB file which is written by XML,  and the user load
this DB file (XML tree in memory), and then do some updating about
this tree, such as delete element, generate new element or move
element.

The thing is, my script is a cmd based program (based on module
"cmd"), and there are many users would use this script at same time,
in a shell style prompt (module "cmd"), so I want to implement a
updating after a user update the XML tree,  it such as a "signal
console",  so that all the user can keep same DB, or other user can
see update a few seconds later.

What I did is, create a new file calling "db_change", and put a number
"1" in file, and then update the real "DB" file (by change uid to lock
file), other user to check this file and then re-load XML file,  but I
do not think it is a good idea, the performance is not good.

I would like to know if you could help on this matter, I hope I can
get inspiration/example from you guys.

Thanks,