05-06-2007
Semaphore
Hi,
I am looking to use a semaphore for the first time in one of my scripts. I am just wondering if there are any simple examples or tutorials around?
I am a beginner so the simpler the better
Thanks
-Jaken
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LEARN ABOUT OSF1
sem_getvalue
sem_getvalue(3) Library Functions Manual sem_getvalue(3)
NAME
sem_getvalue - Gets the value of a specified semaphore (P1003.1b)
LIBRARY
Realtime Library (librt.so, librt.a)
SYNOPSIS
#include <semaphore.h>
int sem_getvalue (
sem_t *sem,
int *sval);
PARAMETERS
sem Specifies a pointer to the semaphore for which a value is to be returned.
sval References a location to be updated with the value of the semaphore indicated by the sem argument.
DESCRIPTION
The sem_getvalue function updates a location referenced by the sval argument with the value of semaphore sem. The updated value represents
an actual semaphore value that occurred during the call, but may not be the actual value of the semaphore at the time that the value is
returned to the calling process.
If the semaphore is locked, the value returned will either be zero or a negative number indicating the number of processes waiting for the
semaphore at some time during the call.
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_getvalue function fails under the following condition:
[EINVAL] The sem argument does not refer to a valid semaphore.
RELATED INFORMATION
Functions: sem_post(3), sem_trywait(3), sem_wait(3)
Guide to Realtime Programming delim off
sem_getvalue(3)