sem_close man page

sem_close ā€” close a named semaphore


#include <semaphore.h>

int sem_close(sem_t *sem);

Link with -pthread.


sem_close() closes the named semaphore referred to by sem, allowing any resources that the system has allocated to the calling process for this semaphore to be freed.

Return Value

On success sem_close() returns 0; on error, -1 is returned, with errno set to indicate the error.



sem is not a valid semaphore.


For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
sem_close() Thread safety MT-Safe

Conforming to

POSIX.1-2001, POSIX.1-2008.


All open named semaphores are automatically closed on process termination, or upon execve(2).

See Also

sem_getvalue(3), sem_open(3), sem_post(3), sem_unlink(3), sem_wait(3), sem_overview(7)


This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By

sem_open(3), sem_overview(7).

2017-09-15 Linux Programmer's Manual