'\" t
.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH sem_destroy 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
sem_destroy \- destroy an unnamed semaphore
.SH LIBRARY
POSIX threads library
.RI ( libpthread ", " \-lpthread )
.SH SYNOPSIS
.nf
.B #include <semaphore.h>
.PP
.BI "int sem_destroy(sem_t *" sem );
.fi
.SH DESCRIPTION
.BR sem_destroy ()
destroys the unnamed semaphore at the address pointed to by
.IR sem .
.PP
Only a semaphore that has been initialized by
.BR sem_init (3)
should be destroyed using
.BR sem_destroy ().
.PP
Destroying a semaphore that other processes or threads are
currently blocked on (in
.BR sem_wait (3))
produces undefined behavior.
.PP
Using a semaphore that has been destroyed produces undefined results,
until the semaphore has been reinitialized using
.BR sem_init (3).
.SH RETURN VALUE
.BR sem_destroy ()
returns 0 on success;
on error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EINVAL
.I sem
is not a valid semaphore.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR sem_destroy ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001.
.SH NOTES
An unnamed semaphore should be destroyed with
.BR sem_destroy ()
before the memory in which it is located is deallocated.
Failure to do this can result in resource leaks on some implementations.
.\" But not on NPTL, where sem_destroy () is a no-op..
.SH SEE ALSO
.BR sem_init (3),
.BR sem_post (3),
.BR sem_wait (3),
.BR sem_overview (7)