개요

• 솔라나라에 설명된 어플리케이션에 대해 맨 페이지를 찾아 출력한다.
• MAN 페이지에 대한 설명은 윈디하나의 솔라나라: MAN 페이지을 참고하자.
• svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.

sem_getvalue(3)

SEM_GETVALUE(3)            Linux Programmer's Manual           SEM_GETVALUE(3)

NAME
       sem_getvalue - get the value of a semaphore

SYNOPSIS
       #include <semaphore.h>

       int sem_getvalue(sem_t *sem, int *sval);

       Link with -pthread.

DESCRIPTION
       sem_getvalue() places the current value of the semaphore pointed to sem
       into the integer pointed to by sval.

       If  one  or  more  processes or threads are blocked waiting to lock the
       semaphore with sem_wait(3), POSIX.1 permits two possibilities  for  the
       value  returned  in  sval:  either  0 is returned; or a negative number
       whose absolute value is the  count  of  the  number  of  processes  and
       threads  currently blocked in sem_wait(3).  Linux adopts the former be‐
       havior.

RETURN VALUE
       sem_getvalue() returns 0 on success; on error, -1 is returned and errno
       is set to indicate the error.

ERRORS
       EINVAL sem is not a valid semaphore.

ATTRIBUTES
       For an explanation of the terms  used  in  this  section,  see  attrib‐
       utes(7).   allbox;  lb  lb  lb  l  l  l.   Interface Attribute Value T{
       sem_getvalue() T}   Thread safety  MT-Safe

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

NOTES
       The value of the  semaphore  may  already  have  changed  by  the  time
       sem_getvalue() returns.

SEE ALSO
       sem_post(3), sem_wait(3), sem_overview(7)

COLOPHON
       This  page  is  part of release 5.02 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
       https://www.kernel.org/doc/man-pages/.

Linux                             2017-09-15                   SEM_GETVALUE(3)