>>> I am looking at a user level approach, not a programmer level approach. >>> >> >> For a user level (requires cooperation) approach, assume you have the same >> app sharing files in the same folder, then this app co-operates with other >> instances by always calling for exclusive lock, then NOT working on the file >> until it can gain the lock. > > I did not expect to be misunderstood on such a grand scale; let me be > more specific. > If a file (inode) has already been opened, all other calls to 'open' > the file should fail. As simple as that. Is there a way to do this > using either the native filesystem, or using samba? > > -aditya
Short answer ... no, its not possible on linux Long answer: In some form its possible. if you mount file system with 'mand' options, and set sticky guid with execute permissions on a file then all fcntl locks on that file become mandatory. It took me a lot of time to understand this so i don't think you should bother. More problems: it has races by design.... also the code and the api is hardly ever used so i will be wary of using it in production environments. And is generally very less understood. Even more problems: mmap is still not locked out, and anything changing stuff from any other api is exempted as well. But in most cases use of advisory locking is sufficient Just take a flock on the file in you app always and the app should co-operate with other instances of the same app. If you can describe the use case may be we can suggest a better solution BAIN _______________________________________ Pune GNU/Linux Users Group Mailing List
