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
       behavior.

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
       attributes(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)