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# PR_OpenSemaphore
Creates or opens a named semaphore with the specified name.
## Syntax
```{code}
#include <pripcsem.h>
#define PR_SEM_CREATE 0x1 /* create if not exist */
#define PR_SEM_EXCL 0x2 /* fail if already exists */
NSPR_API(PRSem *) PR_OpenSemaphore(
const char *name,
PRIntn flags,
PRIntn mode,
PRUintn value
);
```
### Parameters
The function has the following parameters:
`name`
: The name to be given the semaphore.
`flags`
: How to create or open the semaphore.
`mode`
: Unix style file mode to be used when creating the semaphore.
`value`
: The initial value assigned to the semaphore.
### Returns
A pointer to a PRSem structure or `NULL/code> on error.`
### Description
If the named semaphore doesn't exist and the `PR_SEM_CREATE` flag is
specified, the named semaphore is created. The created semaphore needs
to be removed from the system with a {ref}`PR_DeleteSemaphore` call.
If `PR_SEM_CREATE` is specified, the third argument is the access
permission bits of the new semaphore (same interpretation as the mode
argument to {ref}`PR_Open`) and the fourth argument is the initial value of
the new semaphore. `If PR_SEM_CREATE` is not specified, the third and
fourth arguments are ignored.