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Top Forums UNIX for Dummies Questions & Answers Determining which processes hold a semaphore Post 302281778 by Corona688 on Thursday 29th of January 2009 12:02:22 PM
Old 01-29-2009
Can't the process itself remember when its used a semaphore before? Sems don't have that kind of memory, they're just counters and a queue. I've written and deleted many solutions here, realizing partway through that they all fail when a process can't remember how many times its locked it already.
 

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sem_unlink(3)						     Library Functions Manual						     sem_unlink(3)

NAME
sem_unlink - Removes the specified named semaphore (P1003.1b) LIBRARY
Realtime Library (librt.so, librt.a) SYNOPSIS
#include <semaphore.h> int sem_unlink ( const char *name) ; PARAMETERS
*name Specifies the name of the semaphore to remove. DESCRIPTION
The sem_unlink function removes a semaphore named by the string name. If the semaphore is referenced by other processes, sem_unlink does not change the state of the semaphore. If other processes have the semaphore open when sem_unlink is called, the semaphore is not destroyed until all references to the semaphore have been destroyed by calls to sem_close. The sem_unlink function returns immediately; it does not wait until all references have been destroyed. Calls to sem_open to recreate or reconnect to the semaphore refer to a new semaphore after sem_unlink is called. RETURN VALUES
On a successful call, a value of 0 (zero) is returned. Otherwise, a value of -1 is returned and errno is set to indicate that an error occurred. ERRORS
The sem_unlink function fails under the following conditions: [EACCES] Permission is denied to unlink the named semaphore. [ENAMETOOLONG] The length of the name string exceeds {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect. [ENOENT] The named semaphore does not exist. RELATED INFORMATION
Functions: sem_close(3), sem_open(3) Guide to Realtime Programming delim off sem_unlink(3)
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