Write about Semaphores and its usages.

Elaborate Semaphores along with its usage in different areas?

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"Tangible comprehension of OS concepts needs to designing/grow clever programs. Each of our nonsubjective should be to teach you along most of these methods as well as study from different skilled geeks. "

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"In Frontier, the verbs semaphore.lock and semaphore.unlock are used to lock and unlock semaphores, respectively. Semaphores are identified by name (a string), and all processes requiring access to a given shared resource must use the same semaphore. It is not uncommon to use an ODB address for the semaphore name, but that is just for convenience; the semaphore name may be any string. For example, a semaphore to lock a shared table system.temp.sharedTable could be called ""system.temp.sharedTable"", or it could be called ""George""; either would work the same. "

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"Semaphores : A Semaphore is a protected variable whose value can be accessed and altered only by operations P and V. A Semaphore Mechanism basically consists of the two primitive operations SIGNAL and WAIT. The Semaphore variable can assume only positive integer value. The integer value of the Semaphore in the wait and signal operations must be executed indivisible. That is, when one process modifies the Semaphore value, no other process can simultaneously modify that same Semaphore value. Usage : (i) Semaphores can be used to deal with n process critical section problem. As the n processes shares the semaphores, mutex (standing for mutual exclusion), is initialized to 1. (ii) Semaphores can also be used to solve various synchronization problems. Source:"

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