pthread_mu...getpshared(3)

💅 pthread_mu...getpshared(3) — Library Functions Manual

okay bestie, sit down, hydrate, and let me tell you about the cutest little pair of functions in the POSIX threads library 💖 this one lives in section 3 of the manual (that's pthread_mu...getpshared(3) for the search bar girlies) and it's about one very specific lil' mutex attribute.

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🎀 NAME

pthread_mutexattr_getpshared, pthread_mutexattr_setpshared — get/set process-shared mutex attribute ✨

One gets, one sets, they're a duo, they're a package deal, no cap.

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📚 LIBRARY

POSIX threads library — link it with libpthread, -lpthread 🧵

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🌸 SYNOPSIS

#include <pthread.h>

int pthread_mutexattr_getpshared(
                      const pthread_mutexattr_t *restrict attr,
                      int *restrict pshared);
int pthread_mutexattr_setpshared(pthread_mutexattr_t *attr,
                      int pshared);

look at that restrict action. she's careful with her pointers. iconic behavior honestly 👑

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✨ DESCRIPTION

These two functions get and set the process-shared attribute inside a mutex attributes object. And listen, this attribute is not a vibe-only detail — it must be set appropriately, or the mutex you create with this attributes object won't operate correctly and efficiently. it's giving "do it right or don't do it at all" 😭

The process-shared attribute can be one of these two values:

• PTHREAD_PROCESS_PRIVATE — mutexes made with this attributes object are meant to be shared only among threads in the same process that initialized the mutex. This is the default value for the process-shared mutex attribute (so if you do nothing, this is what you get, no thoughts head empty 💭).
• PTHREAD_PROCESS_SHARED — mutexes made with this attributes object can be shared between any threads that have access to the memory containing the object, and yes, that includes threads in different processes. cross-process communication era fr fr 🌈

And now the actual moves:

• pthread_mutexattr_getpshared() — places the value of the process-shared attribute of the mutex attributes object referred to by attr into the location pointed to by pshared. it's the reading one 🫶
• pthread_mutexattr_setpshared() — sets the value of the process-shared attribute of the mutex attributes object referred to by attr to the value specified in pshared. it's the writing one ✍️

⚠️ now the serious bit, bestie: if attr does not refer to an initialized mutex attributes object, the behavior is undefined. undefined is not a vibe. undefined is chaos. do not pass go 💀

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🔥 RETURN VALUE

On success, these functions return 0. On error, they return a positive error number. that's it, that's the whole deal, the numbers don't lie ✨

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😭 ERRORS

pthread_mutexattr_setpshared() can fail with the following errors:

• EINVAL — the value specified in pshared is invalid. you gave it something it does not know, and it is politely declining 🙈
• ENOTSUP — pshared is PTHREAD_PROCESS_SHARED, but the implementation does not support process-shared mutexes. so you asked for the fancy cross-process thing and this system said "we don't do that here" 💀

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📜 STANDARDS

POSIX.1-2008. certified, official, in the standards 💅

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🕰️ HISTORY

POSIX.1-2001. so yeah, she's been around. seasoned. mother is mothering 👑

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🦋 SEE ALSO

• pthread_mutexattr_init(3)
• pthreads(7)

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and that's the whole page, bestie!! go forth and set your attributes responsibly 🌟

this was brought to you by Linux man-pages 6.20, dated 2026-02-08 — mwah, love u, bye 💖🎀🫶