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Full Discussion: semaphore removal
Top Forums UNIX for Dummies Questions & Answers semaphore removal Post 302471606 by jim mcnamara on Sunday 14th of November 2010 05:29:07 AM
Old 11-14-2010
What you are asking is not clear. The only time 600 helps is when the other processes are from another user in another group. And then they cannot do anything with the sempahore anyway, so it becomes pointless for most applications.

IMO, the real issue is: the only process that should ever be able to execute sem_init() or sem_destroy() must be the same one. The other processes should not have access to that code segment. i.e., after fork(), the child process code path does not have sem_destroy() in it. Any other plan means that one of the child processes could clobber the semaphore, the result being undefined.
 

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SEM_UNLINK(2)						      BSD System Calls Manual						     SEM_UNLINK(2)

NAME
sem_unlink -- remove a named semaphore SYNOPSIS
#include <semaphore.h> int sem_unlink(const char *name); DESCRIPTION
The named semaphore named name is removed. If the semaphore is in use by other processes, then name is immediately disassociated with the semaphore, but the semaphore itself will not be removed until all references to it have been closed. Subsequent calls to sem_open() using name will refer to or create a new semaphore named name. If successful, sem_unlink() will return 0. Otherwise, -1 is returned and errno is set, and the state of the semaphore is unchanged. ERRORS
sem_unlink() succeeds unless: [EACCES] Permission is denied to be remove the semaphore. [ENAMETOOLONG] name exceeded PSEMNAMLEN characters. [ENOENT] The named semaphore does not exist. SEE ALSO
sem_close(2), sem_open(2), semctl(2), semget(2), semop(2) HISTORY
sem_unlink() is specified in the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995). Darwin June 8, 2000 Darwin
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