02-10-2009
A semaphore with a value of one will make a good mutex. The first process in gets to decrement the semaphore, every other process has to wait. And when its done it increments the semaphore, letting the next process decrement it and take over.
Some good examples of sysv semaphores
here.
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LEARN ABOUT CENTOS
semaphore.h
semaphore.h(3HEAD) Headers semaphore.h(3HEAD)
NAME
semaphore.h, semaphore - semaphores
SYNOPSIS
#include <semaphore.h>
DESCRIPTION
The <semaphore.h> header defines the sem_t type, used in performing semaphore operations. The semaphore can be implemented using a file
descriptor, in which case applications are able to open up at least a total of {OPEN_MAX} files and semaphores. The symbol SEM_FAILED is
defined (see sem_open(3RT)).
Inclusion of the <semaphore.h> header can make visible symbols defined in the headers <fcntl.h> and <sys/types.h>. See fcntl.h(3HEAD) and
types.h(3HEAD).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO
fcntl.h(3HEAD), types.h(3HEAD), sem_destroy(3RT), sem_getvalue(3RT), sem_init(3RT), sem_open(3RT), sem_post(3RT), sem_timedwait(3RT),
sem_unlink(3RT), sem_wait(3RT), attributes(5), standards(5)
SunOS 5.10 10 Sep 2004 semaphore.h(3HEAD)