semget(2) - osol9

1semget(2)                        System Calls                        semget(2)
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NAME

6       semget - get set of semaphores
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SYNOPSIS

9       #include <sys/types.h>
10       #include <sys/ipc.h>
11       #include <sys/sem.h>
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13       int semget(key_t key, int nsems, int semflg);
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DESCRIPTION

17       The  semget() function returns the semaphore identifier associated with
18       key.
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21       A semaphore identifier and associated data structure and set containing
22       nsems  semaphores (see Intro(2)) are created for key if one of the fol‐
23       lowing is true:
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25           o      key is equal to IPC_PRIVATE.
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27           o      key does not already have a semaphore identifier  associated
28                  with it, and (semflg&IPC_CREAT) is true.
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31       On creation, the data structure associated with the new semaphore iden‐
32       tifier is initialized as follows:
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34           o      sem_perm.cuid, sem_perm.uid, sem_perm.cgid, and sem_perm.gid
35                  are  set  equal to the effective user ID and effective group
36                  ID, respectively, of the calling process.
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38           o      The access permission bits of sem_perm.mode are set equal to
39                  the access permission bits of semflg.
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41           o      sem_nsems is set equal to the value of nsems.
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43           o      sem_otime  is  set  equal to 0 and sem_ctime is set equal to
44                  the current time.
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RETURN VALUES

47       Upon successful completion, a non-negative integer representing a sema‐
48       phore  identifier  is  returned. Otherwise, −1 is returned and errno is
49       set to indicate the error.
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ERRORS

52       The semget() function will fail if:
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54       EACCES    A semaphore identifier exists for key, but operation  permis‐
55                 sion  (see  Intro(2)) as specified by the low-order 9 bits of
56                 semflg would not be granted.
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59       EEXIST    A  semaphore  identifier  exists  for  key  but  both   (sem‐
60                 flg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.
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63       EINVAL    The  nsems  argument  is  either  less  than or equal to 0 or
64                 greater than the system-imposed limit. See NOTES.
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66                 A semaphore identifier exists for key, but the number of sem‐
67                 aphores  in the set associated with it is less than nsems and
68                 nsems is not equal to 0.
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71       ENOENT    A semaphore identifier does  not  exist  for  key  and  (sem‐
72                 flg&IPC_CREAT) is false.
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75       ENOSPC    A  semaphore  identifier  is  to  be  created but the system-
76                 imposed limit on the maximum number of allowed semaphores  or
77                 semaphore  identifiers  system-wide  would  be  exceeded. See
78                 NOTES.
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ATTRIBUTES

82       See attributes(5) for descriptions of the following attributes:
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87       ┌─────────────────────────────┬─────────────────────────────┐
88       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
89       ├─────────────────────────────┼─────────────────────────────┤
90       │Interface Stability          │Standard                     │
91       └─────────────────────────────┴─────────────────────────────┘
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NOTES

98       The  system-imposed  limit  on  the  value of the nsems argument is the
99       maintained on  a  per-process  basis  using  the  process.max-sem-nsems
100       resource control.
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103       The  system-imposed  limit  on  the  number of semaphore identifiers is
104       maintained  on  a  per-project  basis  using  the   project.max-sem-ids
105       resource  control.  The   zone.max-sem-ids  resource  control limis the
106       total number of semaphore identifiers that can be allocated by a zone.
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109       See rctladm(1M) and setrctl(2) for  information  about  using  resource
110       controls.
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114SunOS 5.11                        14 Aug 2006                        semget(2)