Seafile
GiliSoft File Lock is a lite version of the popular GiliSoft File Lock Pro software. It gives you the ability to Lock and Hide your documents, images, videos and other file types with password protection using windows kernel level security.
In Amiga OS , a lock on a file (or directory) can be acquired using the Lock function (in the dos.library). A lock can be shared (other processes can read the file/directory, but can't modify or delete it), or exclusive so that only the process which successfully file lock acquires the lock can access or modify the object. The lock is on the whole object and not part of it. The lock must be released with the UnLock function: unlike in Unix, the operating system does not implicitly unlock the object when the process terminates.
If you break or steal someone else's lock without telling them, you could potentially cause loss of work. If you are working with unmergeable file types and you steal someone else's lock, once you release the lock they are free to check in their changes and overwrite yours. Subversion doesn't lose data, but you have lost the team-working protection that locking gave you.
SQLite uses POSIX advisory locks to implement locking on Unix. On Windows it uses the LockFile(), LockFileEx(), and UnlockFile() system calls. SQLite assumes that these system calls all work as advertised. If that is not the case, then database corruption can result. One should note that POSIX advisory locking is known to be buggy or even unimplemented on many NFS implementations (including recent versions of Mac OS X) and that there are reports of locking problems for network filesystems under Windows. Your best defense is to not use SQLite for files on a network filesystem.
If you run 1st and then the 2nd script,the 2nd script will wait untill the 1st has finished. As soon as the first script finishes, the second one will acquire the lock and finish the execution. If you use flock($file_handle, LOCK_EX LOCK_NB) in the 2nd script while the 1st script is running, it would finish execution immediately and you would not get the lock.
