1IPC::Semaphore(3)     User Contributed Perl Documentation    IPC::Semaphore(3)
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NAME

6       IPC::Semaphore - SysV Semaphore IPC object class
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SYNOPSIS

9           use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR IPC_CREAT);
10           use IPC::Semaphore;
11
12           $sem = IPC::Semaphore->new(IPC_PRIVATE, 10, S_IRUSR | S_IWUSR | IPC_CREAT);
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14           $sem->setall( (0) x 10);
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16           @sem = $sem->getall;
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18           $ncnt = $sem->getncnt;
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20           $zcnt = $sem->getzcnt;
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22           $ds = $sem->stat;
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24           $sem->remove;
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DESCRIPTION

27       A class providing an object based interface to SysV IPC semaphores.
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METHODS

30       new ( KEY , NSEMS , FLAGS )
31           Create a new semaphore set associated with "KEY". "NSEMS" is the
32           number of semaphores in the set. A new set is created if
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34           •   "KEY" is equal to "IPC_PRIVATE"
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36           •   "KEY" does not already have a semaphore identifier associated
37               with it, and "FLAGS & IPC_CREAT" is true.
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39           On creation of a new semaphore set "FLAGS" is used to set the
40           permissions.  Be careful not to set any flags that the Sys V IPC
41           implementation does not allow: in some systems setting execute bits
42           makes the operations fail.
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44       getall
45           Returns the values of the semaphore set as an array.
46
47       getncnt ( SEM )
48           Returns the number of processes waiting for the semaphore "SEM" to
49           become greater than its current value
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51       getpid ( SEM )
52           Returns the process id of the last process that performed an
53           operation on the semaphore "SEM".
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55       getval ( SEM )
56           Returns the current value of the semaphore "SEM".
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58       getzcnt ( SEM )
59           Returns the number of processes waiting for the semaphore "SEM" to
60           become zero.
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62       id  Returns the system identifier for the semaphore set.
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64       op ( OPLIST )
65           "OPLIST" is a list of operations to pass to "semop". "OPLIST" is a
66           concatenation of smaller lists, each which has three values. The
67           first is the semaphore number, the second is the operation and the
68           last is a flags value. See semop(2) for more details. For example
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70               $sem->op(
71                   0, -1, IPC_NOWAIT,
72                   1,  1, IPC_NOWAIT
73               );
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75       remove
76           Remove and destroy the semaphore set from the system.
77
78       set ( STAT )
79       set ( NAME => VALUE [, NAME => VALUE ...] )
80           "set" will set the following values of the "stat" structure
81           associated with the semaphore set.
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83               uid
84               gid
85               mode (only the permission bits)
86
87           "set" accepts either a stat object, as returned by the "stat"
88           method, or a list of name-value pairs.
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90       setall ( VALUES )
91           Sets all values in the semaphore set to those given on the "VALUES"
92           list.  "VALUES" must contain the correct number of values.
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94       setval ( N , VALUE )
95           Set the "N"th value in the semaphore set to "VALUE"
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97       stat
98           Returns an object of type "IPC::Semaphore::stat" which is a sub-
99           class of "Class::Struct". It provides the following fields. For a
100           description of these fields see your system documentation.
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102               uid
103               gid
104               cuid
105               cgid
106               mode
107               ctime
108               otime
109               nsems
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SEE ALSO

112       IPC::SysV, Class::Struct, semget(2), semctl(2), semop(2)
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AUTHORS

115       Graham Barr <gbarr@pobox.com>, Marcus Holland-Moritz <mhx@cpan.org>
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118       Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz.
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120       Version 1.x, Copyright (c) 1997, Graham Barr.
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122       This program is free software; you can redistribute it and/or modify it
123       under the same terms as Perl itself.
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127perl v5.36.0                      2022-07-22                 IPC::Semaphore(3)
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