---
name: "pthread_rwlockattr_setpshared"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "macos"]
url: "https://new.carta.tech/pthread_rwlockattr_setpshared"
---

# pthread\_rwlockattr\_setpshared(3)

set the process shared attribute

## NAME

**pthread\_rwlockattr\_setpshared** – set the process shared attribute

## LIBRARY

POSIX Threads Library (libpthread, -lpthread)

## SYNOPSIS

**#include \<pthread.h\>**

*int*\

**pthread\_rwlockattr\_setpshared**(*pthread\_rwlockattr\_t \*attr*, *int pshared*);

## DESCRIPTION

The **pthread\_rwlockattr\_setpshared**() function sets the process shared attribute of *attr* to the value referenced by *pshared*. The *pshared* argument may be one of two values:

- PTHREAD\_PROCESS\_SHARED

  Any thread of any process that has access to the memory where the read/write lock resides can manipulate the lock.

- PTHREAD\_PROCESS\_PRIVATE

  Only threads created within the same process as the thread that initialized the read/write lock can manipulate the lock. This is the default value.

## RETURN VALUES

If successful, the **pthread\_rwlockattr\_setpshared**() function will return zero. Otherwise an error number will be returned to indicate the error.

## ERRORS

The **pthread\_rwlockattr\_setpshared**() function will fail if:

- \[EINVAL\]

  The value specified by *attr* or *pshared* is invalid.

## SEE ALSO

[pthread\_rwlock\_init(3)](/pthread_rwlock_init/3.md), [pthread\_rwlockattr\_getpshared(3)](/pthread_rwlockattr_getpshared/3.md), [pthread\_rwlockattr\_init(3)](/pthread_rwlockattr_init/3.md)

## STANDARDS

The **pthread\_rwlockattr\_setpshared**() function is expected to conform to Version 2 of the Single UNIX Specification (“SUSv2”).

## HISTORY

The **pthread\_rwlockattr\_setpshared**() function first appeared in FreeBSD 3.0. Support for process-shared read/write locks appeared in FreeBSD 11.0.