xref: /openbsd-src/lib/libpthread/man/sem_init.3 (revision 46035553bfdd96e63c94e32da0210227ec2e3cf1)
1.\" $OpenBSD: sem_init.3,v 1.6 2013/11/20 03:26:56 tedu Exp $
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30.\" $FreeBSD: src/lib/libc_r/man/sem_init.3,v 1.11 2001/10/01 16:09:09 ru Exp $
31.Dd $Mdocdate: November 20 2013 $
32.Dt SEM_INIT 3
33.Os
34.Sh NAME
35.Nm sem_init
36.Nd initialize an unnamed semaphore
37.Sh SYNOPSIS
38.In semaphore.h
39.Ft int
40.Fn sem_init "sem_t *sem" "int pshared" "unsigned int value"
41.Sh DESCRIPTION
42The
43.Fn sem_init
44function initializes the unnamed semaphore pointed to by
45.Fa sem
46to have the value
47.Fa value .
48A non-zero value for
49.Fa pshared
50specifies a shared semaphore that can be used by multiple processes.
51.Pp
52Following a successful call to
53.Fn sem_init ,
54.Fa sem
55can be used as an argument in subsequent calls to
56.Fa sem_wait ,
57.Fa sem_trywait ,
58.Fa sem_post ,
59and
60.Fa sem_destroy .
61.Fa sem
62is no longer valid after a successful call to
63.Fa sem_destroy .
64.Sh RETURN VALUES
65.Rv -std sem_init
66.Sh ERRORS
67It is an error to call
68.Fn sem_destroy
69on a named semaphore created by
70.Fn sem_open .
71.Pp
72.Fn sem_init
73will fail if:
74.Bl -tag -width Er
75.It Bq Er EINVAL
76.Fa value
77exceeds SEM_VALUE_MAX.
78.It Bq Er ENOSPC
79Memory allocation error.
80.El
81.Sh SEE ALSO
82.Xr sem_destroy 3 ,
83.Xr sem_getvalue 3 ,
84.Xr sem_open 3 ,
85.Xr sem_post 3 ,
86.Xr sem_wait 3
87.Sh STANDARDS
88.Fn sem_init
89conforms to
90.St -p1003.1-96 .
91