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 Implementing Semaphores in the Shell

"The Init operation initializes the value of a semaphore. When a process needs a resource, the P operation (which comes from the word "proberen" and means "to test" in Dijkstra's native Dutch language) tests the value of the semaphore and decrements the value if a resource is available. When the value of a semaphore is zero, processes attempting to grab a resource must wait until one becomes available. The V operation (from "verhogen", which means "to increment") frees a resource by incrementing the value of the semaphore."

 (Submitted by Noel Wed Jul 28, 2004 )


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