sem_destroy(3)

✨ sem_destroy(3) — Library Functions Manual ✨

okay bestie, welcome to the sem_destroy(3) page from the Library Functions Manual 💖 this is the one where we say bye-bye to a semaphore, so let's get into it 🫶

---

💫 NAME

sem_destroy — destroy an unnamed semaphore 🌸

---

📚 LIBRARY

POSIX threads library — you're linking libpthread, so pop -lpthread on that compile line, bestie 🎀

---

🦋 SYNOPSIS

#include <semaphore.h>

int sem_destroy(sem_t *sem);

like... that's it. one function. one pointer. iconic behavior tbh 👑

---

💅 DESCRIPTION

so sem_destroy() destroys the unnamed semaphore sitting at the address that sem points to. that's the whole job. she's done. she's retiring 💀

now here's the tea: only a semaphore that was initialized by sem_init(3) should be destroyed using sem_destroy(). don't be out here destroying semaphores that came from somewhere else, that's not the vibe 🙈

⚠️ major warning, no cap: destroying a semaphore that other processes or threads are currently blocked on (like, blocked inside sem_wait(3)) produces undefined behavior. that is the scary kind of undefined. do not do it fr fr 😭

and also: using a semaphore that has already been destroyed produces undefined results, until the semaphore gets reinitialized using sem_init(3). so like, once she's gone she's GONE, no haunting the living unless you properly bring her back ✨

---

🍓 RETURN VALUE

• on success: sem_destroy() returns 0 — we love a clean win 💖
• on error: -1 is returned, and errno is set to indicate the error 📝

---

🌸 ERRORS

• EINVAL — sem is not a valid semaphore. wrong vibe. invalid. rejected 💀

---

🌈 ATTRIBUTES

for an explanation of the terms used in this section, check out attributes(7) (iykyk).

• Interface: sem_destroy()
• Attribute: Thread safety
• Value: MT-Safe 👑

---

⭐ STANDARDS

POSIX.1-2008. periodt ✨

---

🎀 HISTORY

POSIX.1-2001. she's been around a while, a true veteran 💜

---

🧚 NOTES

an unnamed semaphore should be destroyed with sem_destroy() before the memory that it lives in gets deallocated. yes, before. the order matters, bestie 🫶

⚠️ failing to do this can result in resource leaks on some implementations. and leaks are not cute. leaks are the opposite of cute 😭

---

🔥 SEE ALSO

• sem_init(3)
• sem_post(3)
• sem_wait(3)
• sem_overview(7)

---

and that's the whole page, my love 💖 this was Linux man-pages 6.20, dated 2026-02-08, dropping sem_destroy(3) into the group chat. go free that semaphore (but like, responsibly, and after everyone's unblocked) 😌✨🍓👑