1sem_init(3C)             Standard C Library Functions             sem_init(3C)
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NAME

6       sem_init - initialize an unnamed semaphore
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SYNOPSIS

9       #include <semaphore.h>
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11       int sem_init(sem_t *sem, int pshared, unsigned int value);
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DESCRIPTION

15       The  sem_init()  function  is  used to initialize the unnamed semaphore
16       referred to by sem. The value of the initialized  semaphore  is  value.
17       Following a successful call to sem_init(), the semaphore may be used in
18       subsequent calls to sem_wait(3C),  sem_trywait(3C),  sem_post(3C),  and
19       sem_destroy(3C).  This  semaphore remains usable until the semaphore is
20       destroyed.
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23       If the pshared argument has a non-zero value,  then  the  semaphore  is
24       shared between processes; in this case, any process that can access the
25       semaphore sem can use sem for performing sem_wait(3C), sem_trywait(3C),
26       sem_post(3C), and sem_destroy(3C) operations.
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29       Only  sem itself may be used for performing synchronization. The result
30       of referring to copies  of  sem  in  calls  to  sem_wait(3C),  sem_try‐
31       wait(3C), sem_post(3C), and sem_destroy(3C), is undefined.
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34       If  the  pshared argument is zero, then the semaphore is shared between
35       threads of the process; any thread in this process can use sem for per‐
36       forming     sem_wait(3C),     sem_trywait(3C),     sem_post(3C),    and
37       sem_destroy(3C) operations. The use of the semaphore by  threads  other
38       than those created in the same process is undefined.
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41       Attempting  to  initialize  an already initialized semaphore results in
42       undefined behavior.
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45       The sem_open(3C) function is used with named semaphores.
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RETURN VALUES

48       Upon successful completion, the function initializes the  semaphore  in
49       sem. Otherwise, it returns −1 and sets errno to indicate the error.
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ERRORS

52       The sem_init() function will fail if:
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54       EINVAL     The value argument exceeds  SEM_VALUE_MAX.
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57       ENOSPC     A  resource  required  to  initialize the semaphore has been
58                  exhausted, or the resources have reached the limit on  sema‐
59                  phores (SEM_NSEMS_MAX).
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62       ENOSYS     The sem_init() function is not supported by the system.
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65       EPERM      The  process  lacks the appropriate privileges to initialize
66                  the semaphore.
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ATTRIBUTES

70       See attributes(5) for descriptions of the following attributes:
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75       ┌─────────────────────────────┬─────────────────────────────┐
76       │ATTRIBUTE TYPE               │ATTRIBUTE VALUE              │
77       ├─────────────────────────────┼─────────────────────────────┤
78       │Interface Stability          │Committed                    │
79       ├─────────────────────────────┼─────────────────────────────┤
80       │MT-Level                     │MT-Safe                      │
81       ├─────────────────────────────┼─────────────────────────────┤
82       │Standard                     │See standards(5).            │
83       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

86       sem_destroy(3C),     sem_open(3C),     sem_post(3C),      sem_wait(3C),
87       attributes(5), standards(5)
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91SunOS 5.11                        9 Jul 2009                      sem_init(3C)
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