1IPC::Semaphore(3pm)    Perl Programmers Reference Guide    IPC::Semaphore(3pm)
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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_IRWXU IPC_CREAT);
10           use IPC::Semaphore;
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12           $sem = new IPC::Semaphore(IPC_PRIVATE, 10, S_IRWXU ⎪ 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 associ‐
37               ated 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 per‐
40           missions.
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42       getall
43           Returns the values of the semaphore set as an array.
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45       getncnt ( SEM )
46           Returns the number of processes waiting for the semaphore "SEM" to
47           become greater than its current value
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49       getpid ( SEM )
50           Returns the process id of the last process that performed an opera‐
51           tion on the semaphore "SEM".
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53       getval ( SEM )
54           Returns the current value of the semaphore "SEM".
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56       getzcnt ( SEM )
57           Returns the number of processes waiting for the semaphore "SEM" to
58           become zero.
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60       id  Returns the system identifier for the semaphore set.
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62       op ( OPLIST )
63           "OPLIST" is a list of operations to pass to "semop". "OPLIST" is a
64           concatenation of smaller lists, each which has three values. The
65           first is the semaphore number, the second is the operation and the
66           last is a flags value. See semop for more details. For example
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68               $sem->op(
69                   0, -1, IPC_NOWAIT,
70                   1,  1, IPC_NOWAIT
71               );
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73       remove
74           Remove and destroy the semaphore set from the system.
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76       set ( STAT )
77       set ( NAME => VALUE [, NAME => VALUE ...] )
78           "set" will set the following values of the "stat" structure associ‐
79           ated with the semaphore set.
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81               uid
82               gid
83               mode (only the permission bits)
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85           "set" accepts either a stat object, as returned by the "stat"
86           method, or a list of name-value pairs.
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88       setall ( VALUES )
89           Sets all values in the semaphore set to those given on the "VALUES"
90           list.  "VALUES" must contain the correct number of values.
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92       setval ( N , VALUE )
93           Set the "N"th value in the semaphore set to "VALUE"
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95       stat
96           Returns an object of type "IPC::Semaphore::stat" which is a sub-
97           class of "Class::Struct". It provides the following fields. For a
98           description of these fields see your system documentation.
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100               uid
101               gid
102               cuid
103               cgid
104               mode
105               ctime
106               otime
107               nsems
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SEE ALSO

110       IPC::SysV Class::Struct semget semctl semop
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AUTHOR

113       Graham Barr <gbarr@pobox.com>
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116       Copyright (c) 1997 Graham Barr. All rights reserved.  This program is
117       free software; you can redistribute it and/or modify it under the same
118       terms as Perl itself.
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122perl v5.8.8                       2001-09-21               IPC::Semaphore(3pm)
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