[quote author="Indrajeet" date="1308819271"]
2 Apps running on 2 different machines access same file located at some location.
the following recommendation is then the method.
[quote author="loladiro" date="1308819457"]You could place a lock file somewhere, where both machines can access it.[/quote]
However, I doubt that Qt will have something for you. Probably, you have to make the mechanism your self. Is the access from different machines on a frequent basis? If not, you may use a simple technique such as an additional file indicating taht the main file is locked. But it looks like a lot of traps.
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