PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       sem_unlink — remove a named semaphore

SYNOPSIS

       #include <semaphore.h>

       int sem_unlink(const char *name);

DESCRIPTION

       The  sem_unlink()  function  shall  remove the semaphore named by the string name.  If the
       semaphore named by name is currently referenced  by  other  processes,  then  sem_unlink()
       shall  have  no  effect  on  the state of the semaphore. If one or more processes have the
       semaphore open when sem_unlink() is called, destruction  of  the  semaphore  is  postponed
       until  all  references  to  the  semaphore  have  been  destroyed by calls to sem_close(),
       _exit(), or exec.  Calls to sem_open() to recreate or reconnect to the semaphore refer  to
       a  new semaphore after sem_unlink() is called. The sem_unlink() call shall not block until
       all references have been destroyed; it shall return immediately.

RETURN VALUE

       Upon successful  completion,  the  sem_unlink()  function  shall  return  a  value  of  0.
       Otherwise,  the semaphore shall not be changed and the function shall return a value of -1
       and set errno to indicate the error.

ERRORS

       The sem_unlink() function shall fail if:

       EACCES Permission is denied to unlink the named semaphore.

       ENOENT The named semaphore does not exist.

       The sem_unlink() function may fail if:

       ENAMETOOLONG
              The length of the name argument exceeds {_POSIX_PATH_MAX} on systems  that  do  not
              support  the  XSI  option  or  exceeds  {_XOPEN_PATH_MAX}  on XSI systems, or has a
              pathname component that is longer than {_POSIX_NAME_MAX} on  systems  that  do  not
              support  the XSI option or longer than {_XOPEN_NAME_MAX} on XSI systems.  A call to
              sem_unlink() with a name argument that contains the  same  semaphore  name  as  was
              previously  used  in  a successful sem_open() call shall not give an [ENAMETOOLONG]
              error.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       A future version might require the sem_open() and sem_unlink() functions to have semantics
       similar to normal file system operations.

SEE ALSO

       semctl(), semget(), semop(), sem_close(), sem_open()

       The Base Definitions volume of POSIX.1‐2017, <semaphore.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by
       the Institute of Electrical and Electronics Engineers, Inc and The  Open  Group.   In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .